Sample records for lone star gas

  1. Effective Lone Star program reduces unaccounted-for gas

    SciTech Connect (OSTI)

    Wallace, J.E.

    1982-04-01T23:59:59.000Z

    Lone Star's program for holding down its gas losses implements individual remedies for each of six broad categories of unaccounted-for gas: measurement at other than base conditions, meter inaccuracy, meter-reading errors, accounting mistakes, unmetered or unrecorded gas use, and leakage. Even though some of these remedies will not be fully effective for 2 more years, the program's first year of operation has reduced unaccounted-for gas volumes by 9.2%.

  2. Audit of Lone Star Gas Invoices and Billing Procedures, Task #3

    E-Print Network [OSTI]

    Turner, W. D.; Liu, M.

    1997-01-01T23:59:59.000Z

    receives gas delivered to it by Shipper or by the designee of Shipper for Shipper's account. (k) "Point of Delivery" or "Delivery Point" shall mean the point where Transporter delivers gas to Shipper. 2. Measuring Equipment and Testing (a) The gas delivered... by meters of standard type which shall be installed, operated and maintained by Transporter (or its designee). Measurement devices and equipment shall be tested and adjusted for accuracy on a regular schedule by the party metering the gas (the "metering...

  3. Audit of Lone Star Gas Invoices and Billing Procedures, Task #3 

    E-Print Network [OSTI]

    Turner, W. D.; Liu, M.

    1997-01-01T23:59:59.000Z

    desires that Transporter (a) receive gas from Shipper (or its designee) at the Point(s) of Receipt hereinafter set forth and (b) redeliver gas to the Point(s) of Delivery hereinafter set forth; and WHEREAS, Transporter owns and operates a pipeline system... of this Agreement, (iii) available pipeline capacity necessary to maintain Transporter's sales service to its residential and commercial customers and higher priorities of sales service under tariffs filed with applicable regulatory authorities, and (iv) any other...

  4. Lone Star Healthy Streams Final Report

    E-Print Network [OSTI]

    Wagner, Kevin; Redmon, Larry

    13 Progress Report ? July 15, 2010 TWRI submitted Quarter 14 Progress Report ? October 13, 2010 TWRI submitted Quarter 15 Progress Report ? January 14, 2011 TWRI submitted Quarter 16 Progress Report Subtask 1.3: Coordination of project... on July 1, 2010 to provide a 6-month no-cost extension that extended the project end date to March 31, 2011 to allow completion of the Bacteroides analysis and development of the final report. Lone Star Healthy Streams Final Report 13 Subtask...

  5. Lone Star Healthy Streams: Keeping Texas streams clean

    E-Print Network [OSTI]

    Boutwell, Kathryn S.

    2013-01-01T23:59:59.000Z

    time. #31;is prevents fecal material from accumulating in creek pastures during rainy seasons and ending up in streams. ?Results showed that when alternative o -stream water was provided, the amount of time ca#20;le spent in the creek was reduced... Corporation. LONE STAR HEALTHY STREAMS Keeping Texas streams clean Think contaminated water only occurs in developing countries? Even in the United States, high levels of bacteria in some water bodies make them potentially unsuitable for recreation...

  6. Development of a Synergistic, Comprehensive Statewide Lone Star Healthy Streams Program 

    E-Print Network [OSTI]

    Wagner, K.; Redmon, L.; Peterson, J.

    2013-01-01T23:59:59.000Z

    to expand the Lone Star Healthy Streams Program and establish it as the State’s mechanism to provide a coordinated and comprehensive education program designed to increase awareness of the bacteria issues associated with grazing and dairy cattle, poultry...

  7. LoneSTAR Program: Maximizing Energy Efficiency while Protecting the Envrionment

    E-Print Network [OSTI]

    Trevino, E.

    2014-01-01T23:59:59.000Z

    Maximiz ing Energy Eff ic iency whi le Protect ing the Envi ronment LoanSTAR PROGRAM ESL-KT-14-11-31 CATEE 2014: Clean Air Through Efficiency Conference, Dallas, Texas Nov. 18-20 ? Executed 240 loans totaling $407,923,762.32 ? 93 loans to publ... Storage ESL-KT-14-11-31 CATEE 2014: Clean Air Through Efficiency Conference, Dallas, Texas Nov. 18-20 ? LoanSTAR is out of money. ? Must use ESPC. ? Maximum loan amount is too small. ? I have an existing loan so I am ineligible. ? Prepayment penalt ies...

  8. Policy Recommendations for Establishing the LoneSTAR Monitoring and Analysis Program

    E-Print Network [OSTI]

    Claridge, D. E.; O'Neal, D. L.; Turner, W. D.

    1989-01-01T23:59:59.000Z

    energy consumption analyzed?sometimes with monthly data and sometimes with 15-minute or hourly demand data. 6 The levels of monitoring and analysis recommended can be grouped in three categories: 1) Facility/whole building(s) utility data: These data... receiving retrofits 3) Improve retrofit selection in future rounds of the LoanSTAR Program - 4) Provide a detailed data base of energy use in commercial* buildings located in Texas The money for each retrofit financed from the LoanSTAR Program must...

  9. Gas & Stars Aging low-mass stars eject their outer layers.

    E-Print Network [OSTI]

    Barnes, Joshua Edward

    Recycling Gas & Stars #12;Aging low-mass stars eject their outer layers. M57:The Ring Nebula #12;Thor's Emerald Helmet Winds from high-mass stars blow bubbles of hot gas. #12;Supernova blast waves in stars are mixed back into the gas. NGC 6992: Filaments of theVeil Nebula #12;Bubbles blown by high

  10. Vectren Energy Delivery of Ohio (Gas)- Energy Star Home Rebate

    Broader source: Energy.gov [DOE]

    Vectren Energy Delivery of Ohio offers a flat rebate to builders of residential single-family Energy Star certified homes that receive gas service from the company. In order to qualify, homes must...

  11. Lone Star Transmission LLC | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other4Q07) Wind Farm Jump to: navigation,

  12. Rapid Formation of Gas Giant Planets around M Dwarf Stars

    E-Print Network [OSTI]

    Alan P. Boss

    2006-01-20T23:59:59.000Z

    Extrasolar planet surveys have begun to detect gas giant planets in orbit around M dwarf stars. While the frequency of gas giant planets around M dwarfs so far appears to be lower than that around G dwarfs, it is clearly not zero. Previous work has shown that the core accretion mechanism does not seem to be able to form gas giant planets around M dwarfs, because the time required for core formation scales with the orbital period, which lengthens for lower mass stars, resulting in failed (gas-poor) cores unless the gaseous protoplanetary disk survives for > 10 Myr. Disk instability, on the other hand, is rapid enough (~ 1000 yrs) that it should be able to form gas giant protoplanets around even low mass stars well before the gaseous disk disappears. A new suite of three dimensional radiative, gravitational hydrodynamical models is presented that calculates the evolution of initially marginally gravitationally unstable disks with masses of 0.021 to 0.065 solar masses orbiting around stars with masses of 0.1 and 0.5 solar masses, respectively. The models show that gas giant planets are indeed likely to form by the disk instability mechanism in orbit around M dwarf stars, the opposite of the prediction for formation by the core accretion mechanism. This difference offers another observational test for discriminating between these two theoretical end members for giant planet formation. Ongoing and future extrasolar planet searches around M dwarfs by spectroscopy, microlensing, photometry, and astrometry offer the opportunity to help decide between the dominance of the two mechanisms.

  13. Gas and Star Formation in the Circinus Galaxy

    E-Print Network [OSTI]

    For, Bi-Qing; Jarrett, Tom

    2012-01-01T23:59:59.000Z

    We present a detailed study of the Circinus Galaxy, investigating its star formation, dust and gas properties both in the inner and outer disk. To achieve this, we obtained high-resolution Spitzer mid-infrared images with the IRAC (3.6, 5.8, 4.5, 8.0 micron) and MIPS (24 and 70 micron) instruments and sensitive HI data from the Australia Telescope Compact Array (ATCA) and the 64-m Parkes telescope. These were supplemented by CO maps from the Swedish-ESO Submillimetre Telescope (SEST). Because Circinus is hidden behind the Galactic Plane, we demonstrate the careful removal of foreground stars as well as large- and small-scale Galactic emission from the Spitzer images. We derive a visual extinction of Av = 2.1 mag from the Spectral Energy Distribution of the Circinus Galaxy and total stellar and gas masses of 9.5 x 10^{10} Msun and 9 x 10^9 Msun, respectively. Using various wavelength calibrations, we find obscured global star formation rates between 3 and 8 Msun yr^{-1}. Star forming regions in the inner spira...

  14. Kinematics of gas and stars in circumnuclear star-forming regions of early type spirals

    E-Print Network [OSTI]

    Guillermo F. Hagele; Angeles I. Diaz; Monica V. Cardaci; Elena Terlevich; Roberto Terlevich

    2008-01-20T23:59:59.000Z

    (Abbr.) We present high resolution (R~20000) spectra in the blue and the far red of cicumnuclear star-forming regions (CNSFRs) in three early type spirals (NGC3351, NGC2903 and NGC3310) which have allowed the study of the kinematics of stars and ionized gas in these structures and, for the first time, the derivation of their dynamical masses for the first two. In some cases these regions, about 100 to 150 pc in size, are seen to be composed of several individual star clusters with sizes between 1.5 and 4.9 pc estimated from Hubble Space Telescope (HST) images. The stellar dispersions have been obtained from the Calcium triplet (CaT) lines at $\\lambda\\lambda$ 8494,8542,8662 \\AA, while the gas velocity dispersions have been measured by Gaussian fits to the H$\\beta$ and [OIII] $\\lambda\\lambda$ 5007 \\AA lines on the high dispersion spectra. Values of the stellar velocity dispersions are between 30 and 68 km/s. We apply the virial theorem to estimate dynamical masses of the clusters, assuming that systems are gravitationally bounded and spherically symmetric, and using previously measured sizes. The measured values of the stellar velocity dispersions yield dynamical masses of the order of 10$^7$ to 10$^8$ solar masses for the whole CNSFRs. Stellar and gas velocity dispersions are found to differ by about 20 to 30 km/s with the H$\\beta$ emission lines being narrower than both the stellar lines and the [OIII] $\\lambda\\lambda$ 5007 \\AA lines. The twice ionized oxygen, on the other hand, shows velocity dispersions comparable to those shown by stars, in some cases, even larger. We have found indications of the presence of two different kinematical components in the ionized gas of the regions...

  15. Kinematics of gas and stars in circumnuclear star-forming regions of early type spirals

    E-Print Network [OSTI]

    Hagele, Guillermo F; Cardaci, Monica V; Terlevich, Elena; Terlevich, Roberto

    2008-01-01T23:59:59.000Z

    (Abbr.) We present high resolution (R~20000) spectra in the blue and the far red of cicumnuclear star-forming regions (CNSFRs) in three early type spirals (NGC3351, NGC2903 and NGC3310) which have allowed the study of the kinematics of stars and ionized gas in these structures and, for the first time, the derivation of their dynamical masses for the first two. In some cases these regions, about 100 to 150 pc in size, are seen to be composed of several individual star clusters with sizes between 1.5 and 4.9 pc estimated from Hubble Space Telescope (HST) images. The stellar dispersions have been obtained from the Calcium triplet (CaT) lines at $\\lambda\\lambda$ 8494,8542,8662 \\AA, while the gas velocity dispersions have been measured by Gaussian fits to the H$\\beta$ and [OIII] $\\lambda\\lambda$ 5007 \\AA lines on the high dispersion spectra. Values of the stellar velocity dispersions are between 30 and 68 km/s. We apply the virial theorem to estimate dynamical masses of the clusters, assuming that systems are grav...

  16. StarWars technology may revolutionize natural gas drilling

    SciTech Connect (OSTI)

    NONE

    1998-06-01T23:59:59.000Z

    A 2-year basic research project will examine the feasibility, costs, benefits and environmental impact of applying laser technologies to drill and complete wells. An improved understanding of laser applications could lead to the development of several products, including a downhole laser drilling machine, laser-assisted drill bits for both conventional and coiled tubing applications, a laser perforating tool and sidetrack and directional laser drilling devices. The laser drilling consortium has five primary objectives: determine the amount of data available on StarWars laser technologies; evaluate the capabilities and limitations of applying lasers to drill and complete gas wells; decide what areas of laser drilling research need to be addressed; quantify benefits that can be obtained from laser drilling, such as higher penetration rates, reduced rig day rates and casing requirements, and improved safety and economics; and undertake laboratory research to understand laser, rock and fluid interactions.

  17. Greenhouse Gas Emission Reduction in the ENERGY STAR Commercial, Industrial and Residential Sectors. An Example of How the Refinery Industry is Capitalizing on ENERGY STAR

    E-Print Network [OSTI]

    Patrick, K.

    2008-01-01T23:59:59.000Z

    Greenhouse Gas Emission Reduction in the ENERGY STAR Commercial, Industrial and Residential Sectors. An Example of how the Refinery Industry is Capitalizing on ENERGY STAR Kelly Patrick U.S. Environmental Protection Agency kelly...

  18. Baltimore Gas and Electric Company- Home Performance with Energy Star Rebates

    Broader source: Energy.gov [DOE]

    The Baltimore Gas and Electric Company (BG&E) offers the Home Performance with Energy Star Program that provides incentives for residential customers who have audits performed by participating...

  19. Lone Star Healthy Streams: Teaching best managment practices statewide

    E-Print Network [OSTI]

    Lee, Leslie

    2011-01-01T23:59:59.000Z

    bacterial loading, was developed through the project Copano Bay Water Quality Education. That program was developed and implemented in response to bacterial water quality issues in Copano Bay that impaired oyster harvest in the bay and contact... practices statewide Institute (TWRI). ?It will provide a one-stop shop for the livestock industry and natural resource agencies to access information regarding bacterial water quality issues related to livestock, as well as measures that can...

  20. Clean Cities: Lone Star Clean Fuels Alliance (Central Texas) coalition

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office511041clothAdvanced Materials Advanced. C o w l i t z CPlasma0 12Denver MetroHonolulu CleanIowaLand

  1. Lone Star I (Q2) Wind Farm | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other AlternativePark,CedarPowerViewLomaQ2) Wind

  2. Lone Star I (Q3) Wind Farm | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other AlternativePark,CedarPowerViewLomaQ2)

  3. Lone Star Wind Alliance LSWA | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other4Q07) Wind Farm Jump to: navigation,Wind

  4. OY Car During Normal Outburst: Balmer Emission From The Red Star And The Gas Stream

    E-Print Network [OSTI]

    E. T. Harlaftis; T. R. Marsh

    1995-03-07T23:59:59.000Z

    We present observations of OY Car, obtained with the Anglo-Australian Telescope, during a normal outburst in August 1991. Two sinusoidal components are resolved in the H$\\beta$ trailed spectra and we determine the location of the narrow component to be on the secondary star with a maximum contributed flux of ~2.5 per cent to the total flux. Imaging of the line distribution reveals that the other emission component is associated with the gas stream. This follows a velocity close to the ballistic one from the red star to a distance of ~0.5 R$_{L_{1}}$ from the white dwarf. This emission penetrates the accretion disc (from 0.5--0.1 R$_{L_{1}}$), with a velocity now closer (but lower) to the keplerian velocities along the path of the gas stream. We finally discuss the implications of having observed simultaneously line emission from the gas stream and the red star during outburst.

  5. OY Car in Outburst: Balmer emission from the red star and the gas stream

    E-Print Network [OSTI]

    E. T. Harlaftis; T. R. Marsh

    1995-10-04T23:59:59.000Z

    We present observations of OY Car, obtained with the Anglo-Australian telescope, during a normal outburst in 1991. Two sinusoidal components are resolved in the Hbeta trailed spectra and we determine the location of the narrow component to be on the secondary star with a maximum contributed flux of ~2.5 per cent to the total flux. Imaging of the line distribution reveals that the other emission component is associated with the gas stream. This follows a velocity close to the ballistic one from the red star to a distance of ~0.5 R_L1 from the white dwarf. Then. its kinematics changes from 0.5-0.2 R_L1 (accretion disc) following velocities now closer to (but lower than) the keplerian velocities along the path of the gas stream. We finally dicsuss the implications of having observed simultaneously line emission from the gas stream and the red star during outburst.

  6. Warm Gas in the Inner Disks around Young Intermediate Mass Stars

    E-Print Network [OSTI]

    Sean Brittain; Theodore Simon; Joan Najita; Terrence Rettig

    2006-12-08T23:59:59.000Z

    The characterization of gas in the inner disks around young stars is of particular interest because of its connection to planet formation. In order to study the gas in inner disks, we have obtained high-resolution K-band and M-band spectroscopy of 14 intermediate mass young stars. In sources that have optically thick inner disks, i.e. E(K-L)>1, our detection rate of the ro-vibrational CO transitions is 100% and the gas is thermally excited. Of the five sources that do not have optically thick inner disks, we only detect the ro-vibrational CO transitions from HD 141569. In this case, we show that the gas is excited by UV fluorescence and that the inner disk is devoid of gas and dust. We discuss the plausibility of the various scenarios for forming this inner hole. Our modeling of the UV fluoresced gas suggests an additional method by which to search for and/or place stringent limits on gas in dust depleted regions in disks around Herbig Ae/Be stars.

  7. Vortex Shedding on Hydrofoils Its dark and lonely down there...

    E-Print Network [OSTI]

    Vortex Shedding on Hydrofoils Its dark and lonely down there... Improving marine vehicle an underwater vehicle moves, it displaces water, genera6ng a unique velocity that it can u6lize rather than fight those flows, saving energy and improving

  8. Cool Gas and Massive Stars - the Nuclear Ring in M100

    E-Print Network [OSTI]

    Emma L. Allard; Reynier F. Peletier; Johan H. Knapen

    2005-09-26T23:59:59.000Z

    The SAURON integral field spectrograph was used to observe the central area of the barred spiral galaxy M100 (NGC 4321). M100 contains a nuclear ring of star formation, fueled by gas channeled inward by the galaxy's bar. We present maps of emission line strengths, absorption line strength indices, and the gas velocity dispersion across the field. The H beta emission is strongest in the ring, along two curved bar dustlanes and at the ends of the bar. The Mg b absorption line strength shows a younger population of stars within the ring as compared to the surrounding area. The gas velocity dispersion is notably smaller than elsewhere in the field both in the ring and along the leading edge of the dustlanes. Low gas dispersion is correlated spatially with the H beta emission. We thus see stars being formed from cold (low dispersion) gas which is being channeled inward along the dustlanes under the influence of a large bar, and accumulated into a ring near the location of the inner Lindblad resonances. This lends further strong support to the interpretation of nuclear rings in barred galaxies as resonance phenomena.

  9. Properties of the ionized gas of circumnuclear star-forming regions in early type spirals

    E-Print Network [OSTI]

    Diaz, Angeles I; Terlevich, Elena; Terlevich, Roberto

    2008-01-01T23:59:59.000Z

    (Abbr.) A study of cicumnuclear star-forming regions (CNSFRs) in several early type spirals has been made in order to investigate their main properties: stellar and gas kinematics, dynamical masses, ionising stellar masses, chemical abundances and other properties of the ionised gas. Both high resolution (R$ \\sim $20000) and moderate resolution (R ~ 5000) have been used. In some cases these regions, about 100 to 150 pc in size, are seen to be composed of several individual star clusters with sizes between 1.5 and 4.9 pc estimated from Hubble Space Telescope (HST) images. Stellar and gas velocity dispersions are found to differ by about 20 to 30 km/s with the H$\\beta$ emission lines being narrower than both the stellar lines and the [OIII] $\\lambda$ 5007 \\AA lines. The twice ionized oxygen, on the other hand, shows velocity dispersions comparable to those shown by stars. We have applied the virial theorem to estimate dynamical masses of the clusters, assuming that systems are gravitationally bounded and spheri...

  10. Properties of the ionized gas of circumnuclear star-forming regions in early type spirals

    E-Print Network [OSTI]

    Angeles I. Diaz; Guillermo F. Hagele; Elena Terlevich; Roberto Terlevich

    2008-01-20T23:59:59.000Z

    (Abbr.) A study of cicumnuclear star-forming regions (CNSFRs) in several early type spirals has been made in order to investigate their main properties: stellar and gas kinematics, dynamical masses, ionising stellar masses, chemical abundances and other properties of the ionised gas. Both high resolution (R$ \\sim $20000) and moderate resolution (R ~ 5000) have been used. In some cases these regions, about 100 to 150 pc in size, are seen to be composed of several individual star clusters with sizes between 1.5 and 4.9 pc estimated from Hubble Space Telescope (HST) images. Stellar and gas velocity dispersions are found to differ by about 20 to 30 km/s with the H$\\beta$ emission lines being narrower than both the stellar lines and the [OIII] $\\lambda$ 5007 \\AA lines. The twice ionized oxygen, on the other hand, shows velocity dispersions comparable to those shown by stars. We have applied the virial theorem to estimate dynamical masses of the clusters, assuming that systems are gravitationally bounded and spherically symmetric, and using previously measured sizes. The measured values of the stellar velocity dispersions yield dynamical masses of the order of 10$^7$ to 10$^8$ solar masses for the whole CNSFRs. ...

  11. The Evolving ISM in the Milky Way & Nearby Galaxies ISM Theory: Gas Phases, Turbulence, and Star Formation

    E-Print Network [OSTI]

    and fills much of the volume near the Galactic midplan, and cold atomic gas, which is organized into denseThe Evolving ISM in the Milky Way & Nearby Galaxies ISM Theory: Gas Phases, Turbulence, and Star modeling efforts have begun to take into account the effects of multiscale, time- dependent processes

  12. Gas Dynamics in NGC 5248: Fueling a Circumnuclear Starburst Ring of Super Star Clusters

    E-Print Network [OSTI]

    Shardha Jogee; Isaac Shlosman; Seppo Laine; Peter Englmaier; Johan H. Knapen; Nick Z. Scoville; Christine D. Wilson

    2002-04-03T23:59:59.000Z

    Through observations and modeling, we demonstrate how the recently discovered large-scale bar in NGC 5248 generates spiral structure which extends from 10 kpc down to 100 pc, fuels star formation on progressively smaller scales, and drives disk evolution. Deep inside the bar, two massive molecular spirals cover nearly 180 degrees in azimuth, show streaming motions of 20--40 km/s and feed a starburst ring of super star clusters at 375 pc. They also connect to two narrow K-band spirals which delineate the UV-bright star clusters in the ring. The data suggest that the K-band spirals are young, and the starburst has been triggered by a bar-driven spiral density wave (SDW). The latter may even have propagated closer to the center where a second Halpha ring and a dust spiral are found. The molecular and HST data support a scenario where stellar winds and supernovae efficiently clear out gas from dense star-forming regions on timescales less than a few Myrs. We have investigated the properties of massive CO spirals within the framework of bar-driven SDWs, incorporating the effect of gas self-gravity. We find good agreement between the model predictions and the observed morphology, kinematics, and pitch angle of the spirals. This combination of observations and modeling provides the best evidence to date for a strong dynamical coupling between the nuclear region and the surrounding disk. It also confirms that a low central mass concentration, which may be common in late-type galaxies, is particularly favorable to the propagation of a bar-driven gaseous SDW deep into the central region of the galaxy, whereas a large central mass concentration favors other processes, such as the formation and decoupling of nuclear bars.

  13. Nuclear Bar, Star Formation and Gas Fueling in the Active Galaxy NGC 4303

    E-Print Network [OSTI]

    L. Colina; K. Wada

    1999-10-19T23:59:59.000Z

    A combination of Hubble Space Telescope (HST) WFPC2 and NICMOS images are used to investigate the gas/dust and stellar structure inside the central 300 pc of the nearby active galaxy NGC 4303. The NICMOS H-band (F160W) image reveals a bright core and a nuclear elongated bar-like structure of 250 pc in diameter. The bar is centered on the bright core, and its major axis is oriented in proyection along the spin axis of the nuclear gaseous rotating disk recently detected (Colina & Arribas 1999). The V-H (F606W - F160W) image reveals a complex gas/dust distribution with a two-arm spiral structure of about 225 pc in radius. The southwestern arm is traced by young star-forming knots while the northeastern arm is detected by the presence of dust lanes. These spirals do not have a smooth structure but rather they are made of smaller flocculent spirals or filament-like structures. The magnitudes and colors of the star-forming knots are typical of clusters of young stars with masses of 0.5 to 1 x $10^5 M_{solar}, and ages of 5 to 25 million years. The overall structure of the nuclear spirals as well as the size, number and masses of the star-forming knots are explained in the context of a massive gaseous nuclear disk subject to self-gravitational instabilities and to the gravitational field created by the nuclear bar. According to the model, the gaseous disk has a mass of about 5 x 10^7 M_{solar} inside a radius of 400 pc, the bar has a radius of 150 pc and a pattern speed of about 0.5 Myr^{-1}, and the average mass accretion rate into the core (R < 8 pc) is about 0.01 M_{solar}$ yr^{-1} for about 80 Myr.

  14. Galaxy Pairs in the Sloan Digital Sky Survey - X: Does gas content alter star formation rate enhancement in galaxy interactions?

    E-Print Network [OSTI]

    Scudder, Jillian M; Momjian, Emmanuel; Rosenberg, Jessica L; Torrey, Paul; Patton, David R; Mendel, J Trevor

    2015-01-01T23:59:59.000Z

    New spectral line observations, obtained with the Jansky Very Large Array (VLA), of a sample of 34 galaxies in 17 close pairs are presented in this paper. The sample of galaxy pairs is selected to contain galaxies in close, major interactions (i.e., projected separations $ 3\\sigma$. We compare the HI gas fraction of the galaxies with the triggered star formation present in that galaxy. When compared to the star formation rates (SFRs) of non-pair galaxies matched in mass, redshift, and local environment, we find that the star formation enhancement is weakly positively correlated ($\\sim 2.5\\sigma$) with HI gas fraction. In order to help understand the physical mechanisms driving this weak correlation, we also present results from a small suite of binary galaxy merger simulations with varying gas fractions. The simulated galaxies indicate that larger initial gas fractions are associated with lower levels of interaction-triggered star formation (relative to an identical galaxy in isolation), but also show that hi...

  15. Dead poets' society New England, the 1950s. Todd Anderson (Ethan Hawke), a lonely and painfully

    E-Print Network [OSTI]

    Schenato, Luca

    Dead poets' society New England, the 1950s. Todd Anderson (Ethan Hawke), a lonely and painfully shy in it. After seeing that Mr. Keating listed "Dead Poets Society" as one of his activities at the school

  16. The Formation of the First Low-Mass Stars From Gas With Low Carbon and Oxygen Abundances

    E-Print Network [OSTI]

    Volker Bromm; Abraham Loeb

    2003-10-21T23:59:59.000Z

    The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few hundred solar masses. Numerical simulations indicate that once a gas clump acquires this mass, it undergoes a slow, quasi-hydrostatic contraction without further fragmentation. Here we show that as soon as the primordial gas - left over from the Big Bang - is enriched by supernovae to a carbon or oxygen abundance as small as ~0.01-0.1% of that found in the Sun, cooling by singly-ionized carbon or neutral oxygen can lead to the formation of low-mass stars. This mechanism naturally accommodates the discovery of solar mass stars with unusually low (10^{-5.3} of the solar value) iron abundance but with a high (10^{-1.3} solar) carbon abundance. The minimum stellar mass at early epochs is partially regulated by the temperature of the cosmic microwave background. The derived critical abundances can be used to identify those metal-poor stars in our Milky Way galaxy with elemental patterns imprinted by the first supernovae.

  17. The Formation of the First Low-Mass Stars From Gas With Low Carbon and Oxygen Abundances

    E-Print Network [OSTI]

    Bromm, V; Bromm, Volker; Loeb, Abraham

    2003-01-01T23:59:59.000Z

    The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few hundred solar masses. Numerical simulations indicate that once a gas clump acquires this mass, it undergoes a slow, quasi-hydrostatic contraction without further fragmentation. Here we show that as soon as the primordial gas - left over from the Big Bang - is enriched by supernovae to a carbon or oxygen abundance as small as ~0.01-0.1% of that found in the Sun, cooling by singly-ionized carbon or neutral oxygen can lead to the formation of low-mass stars. This mechanism naturally accommodates the discovery of solar mass stars with unusually low (10^{-5.3} of the solar value) iron abundance but with a high (10^{-1.3} solar) carbon abundance. The minimum stellar mass at early epochs is partially regulated by the temperature of the cosmic microwave background. The derived critical...

  18. STAR

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Scienceand Requirements RecentlyElectronicResourcesjobsJuly throughR E Q U E N C4Safety STAR

  19. Influence of Stellar Multiplicity On Planet Formation. III. Adaptive Optics Imaging of Kepler Stars With Gas Giant Planets

    E-Print Network [OSTI]

    Wang, Ji; Horch, Elliott P; Xie, Ji-Wei

    2015-01-01T23:59:59.000Z

    As hundreds of gas giant planets have been discovered, we study how these planets form and evolve in different stellar environments, specifically in multiple stellar systems. In such systems, stellar companions may have a profound influence on gas giant planet formation and evolution via several dynamical effects such as truncation and perturbation. We select 84 Kepler Objects of Interest (KOIs) with gas giant planet candidates. We obtain high-angular resolution images using telescopes with adaptive optics (AO) systems. Together with the AO data, we use archival radial velocity data and dynamical analysis to constrain the presence of stellar companions. We detect 59 stellar companions around 40 KOIs for which we develop methods of testing their physical association. These methods are based on color information and galactic stellar population statistics. We find evidence of suppressive planet formation within 20 AU by comparing stellar multiplicity. The stellar multiplicity rate for planet host stars is 0$^{+5...

  20. Development of a Synergistic, Comprehensive Statewide Lone Star Healthy Streams Program

    E-Print Network [OSTI]

    Wagner, K.; Redmon, L.; Peterson, J.

    2013-01-01T23:59:59.000Z

    resource manuals and five presentations on bacteria issues and associated BMPs for four major classes of livestock as well as feral hogs. These materials have been made available through not only a resource website, which alone reached almost 1........................................................................................................................ 12 Task 4: Development of an Interactive Website to Increase Access to LSHS Program ........... 14 Subtask 4.1: Distribution of education materials developed in Task 2 though development of an interactive website...

  1. Doing science: teachers' authentic experiences at the Lone Star Dinosaur Field Institute

    E-Print Network [OSTI]

    Stiles, Thomas William

    2001-01-01T23:59:59.000Z

    to participate in the Institute. The teachers willingly shared their expert views on science teaching and learning and kindly allowed me to document all their activities as they participated in the processes of field paleontology. The scientists Dr. Dale...'s, when professional development was commonly referred to as teacher inservice, experts were often hired to teach teachers about particular teaching innovations and programs that were to be implemented in their schools (Louckes-Horsley, Hewson...

  2. Physiological Ageing as it is Related to Gene Function in the Lone Star Tick, Amblyomma americanum

    E-Print Network [OSTI]

    Catena, Amanda M.

    2010-07-14T23:59:59.000Z

    ..................... 12 Figure 2 Electrophoresis gel results for the expression of the ATP synthase gene in Amblyomma americanum subdivided by the mortality percentile to the right of the result, the sample number over the top of the result, and the group... ............................ 15 Figure 4 Electrophoresis gel results for the expression of the 16S gene in Amblyomma americanum subdivided by the mortality percentile to the right of the result, the sample number over the top of the result, and the group...

  3. "Climate Wise" in the Lone Star State: A Successful Partnership for Energy Efficiency in Austin, Texas

    E-Print Network [OSTI]

    Allen, S. J.; Schare, S.

    The City of Austin, Texas is forming partnerships with local companies to lower energy consumption and improve environmental performance within the industrial sector. As a local government participant in the federal Climate Wise program, Austin...

  4. Energy Engineering Analysis (EEA) program for Lone Star Army Ammunition Plant, Texas. Executive summary. Final report

    SciTech Connect (OSTI)

    NONE

    1981-12-31T23:59:59.000Z

    The objective of this Energy Engineering Analysis (EEA) for LSAAP is threefold: Develop a systematic plan of projects which will result in reducing energy consumption. Consider renewable energy sources with the objective of establishing an orderly procedure for reducing use of non-renewable energy sources. Determine the feasibility of Total Energy (TE), Selective Energy (SE), and Central Heating Plant (CHP) concepts using alternative fuels. In essence, an assessment of the entire energy picture at LSAAP was undertaken. This report is a summary of that effort. LSAAP was originally built during 1941 and 1942 as a shell loading plant for the Army. After World War II, the facility was deactivated until 1951 when it was reactivated as a Government Owned, Contractor Operated (GOCO) facility. Day and Zimmerman was selected as the operator in 1951 and has been the operating contractor ever since. Located just west of Texarkana, Texas, LSAAP encompasses an area of approximately 15,546 acres. The primary mission of LSAAP is to load, assemble and pack ammunition and ammunition components for the Army.

  5. "Climate Wise" in the Lone Star State: A Successful Partnership for Energy Efficiency in Austin, Texas 

    E-Print Network [OSTI]

    Allen, S. J.; Schare, S.

    1997-01-01T23:59:59.000Z

    The City of Austin, Texas is forming partnerships with local companies to lower energy consumption and improve environmental performance within the industrial sector. As a local government participant in the federal Climate Wise program, Austin...

  6. Lone Star Reds: the Socialist Party and cotton tenancy in Texas, 1901-1917

    E-Print Network [OSTI]

    Mellard, Jason Dean

    2000-01-01T23:59:59.000Z

    starting somewhere north of Dallas-Fort Worth, running south-southwest along the route of present day Interstate 35 through Waco and Austin, and narrowing to a point just above San Antonio. Here, the rich, sticky, black soil produced the most bales per...

  7. Lone Star I (4Q07) Wind Farm | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other AlternativePark,CedarPowerViewLoma

  8. Lone Star II (1Q08) Wind Farm | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other AlternativePark,CedarPowerViewLomaQ2)II

  9. Lone Star II (2Q08) Wind Farm | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other

  10. Lone Star II (4Q07) Wind Farm | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOf KilaueaInformation Other4Q07) Wind Farm Jump to: navigation, search

  11. Neutral hydrogen gas, past and future star-formation in galaxies in and around the 'Sausage' merging galaxy cluster

    E-Print Network [OSTI]

    Stroe, Andra; Rottgering, Huub J A; Sobral, David; van Weeren, Reinout; Dawson, William

    2015-01-01T23:59:59.000Z

    CIZA J2242.8+5301 ($z = 0.188$, nicknamed 'Sausage') is an extremely massive ($M_{200}\\sim 2.0 \\times 10^{15}M_\\odot$ ), merging cluster with shock waves towards its outskirts, which was found to host numerous emission-line galaxies. We performed extremely deep Westerbork Synthesis Radio Telescope HI observations of the 'Sausage' cluster to investigate the effect of the merger and the shocks on the gas reservoirs fuelling present and future star formation (SF) in cluster members. By using spectral stacking, we find that the emission-line galaxies in the 'Sausage' cluster have, on average, as much HI gas as field galaxies (when accounting for the fact cluster galaxies are more massive than the field galaxies), contrary to previous studies. Since the cluster galaxies are more massive than the field spirals, they may have been able to retain their gas during the cluster merger. The large HI reservoirs are expected to be consumed within $\\sim0.75-1.0$ Gyr by the vigorous SF and AGN activity and/or driven out by t...

  12. Molecular and atomic gas in dust lane early-type galaxies - I: Low star-formation efficiencies in minor merger remnants

    E-Print Network [OSTI]

    Davis, Timothy A; Allison, James R; Shabala, Stanislav S; Ting, Yuan-Sen; Lagos, Claudia del P; Kaviraj, Sugata; Bourne, Nathan; Dunne, Loretta; Eales, Steve; Ivison, Rob J; Maddox, Steve; Smith, Daniel J B; Smith, Matthew W L; Temi, Pasquale

    2015-01-01T23:59:59.000Z

    In this work we present IRAM-30m telescope observations of a sample of bulge-dominated galaxies with large dust lanes, which have had a recent minor merger. We find these galaxies are very gas rich, with H2 masses between 4x10^8 and 2x10^10 Msun. We use these molecular gas masses, combined with atomic gas masses from an accompanying paper, to calculate gas-to-dust and gas-to-stellar mass ratios. The gas-to-dust ratios of our sample objects vary widely (between ~50 and 750), suggesting many objects have low gas-phase metallicities, and thus that the gas has been accreted through a recent merger with a lower mass companion. We calculate the implied minor companion masses and gas fractions, finding a median predicted stellar mass ratio of ~40:1. The minor companion likely had masses between ~10^7 - 10^10 Msun. The implied merger mass ratios are consistent with the expectation for low redshift gas-rich mergers from simulations. We then go on to present evidence that (no matter which star-formation rate indicator ...

  13. Observations of the Gas Reservoir around a Star Forming Galaxy in the Early Universe

    E-Print Network [OSTI]

    Brenda L. Frye; David. V. Bowen; Mairead Hurley; Todd M. Tripp; Xiaohui Fan; Bradley Holden; Puragra Guhathakurta; Dan Coe; Tom Broadhurst; Eiichi Egami; G. Meylan

    2008-08-08T23:59:59.000Z

    We present a high signal-to-noise spectrum of a bright galaxy at z = 4.9 in 14 h of integration on VLT FORS2. This galaxy is extremely bright, i_850 = 23.10 +/- 0.01, and is strongly-lensed by the foreground massive galaxy cluster Abell 1689 (z=0.18). Stellar continuum is seen longward of the Ly-alpha emission line at ~7100 \\AA, while intergalactic H I produces strong absorption shortward of Ly-alpha. Two transmission spikes at ~6800 Angstroms (A) and ~7040 A are also visible, along with other structures at shorter wavelengths. Although fainter than a QSO, the absence of a strong central ultraviolet flux source in this star forming galaxy enables a measurement of the H I flux transmission in the intergalactic medium (IGM) in the vicinity of a high redshift object. We find that the effective H I optical depth of the IGM is remarkably high within a large 14 Mpc (physical) region surrounding the galaxy compared to that seen towards QSOs at similar redshifts. Evidently, this high-redshift galaxy is located in a region of space where the amount of H I is much larger than that seen at similar epochs in the diffuse IGM. We argue that observations of high-redshift galaxies like this one provide unique insights on the nascent stages of baryonic large-scale structures that evolve into the filamentary cosmic web of galaxies and clusters of galaxies observed in the present universe.

  14. Liquid-gas coexistence vs. energy minimization with respect to the density profile in the inhomogeneous inner crust of neutron stars

    E-Print Network [OSTI]

    Noël Martin; Michael Urban

    2015-05-26T23:59:59.000Z

    We compare two approaches to describe the inner crust of neutron stars: on the one hand, the simple coexistence of a liquid (clusters) and a gas phase, and on the other hand, the energy minimization with respect to the density profile, including Coulomb and surface effects. We find that the phase-coexistence model gives a reasonable description of the densities in the clusters and in the gas, but the precision is not high enough to obtain the correct proton fraction at low baryon densities. We also discuss the surface tension and neutron skin obtained within the energy minimization.

  15. Liquid-gas coexistence vs. energy minimization with respect to the density profile in the inhomogeneous inner crust of neutron stars

    E-Print Network [OSTI]

    Martin, Noël

    2015-01-01T23:59:59.000Z

    We compare two approaches to describe the inner crust of neutron stars: on the one hand, the simple coexistence of a liquid (clusters) and a gas phase, and on the other hand, the energy minimization with respect to the density profile, including Coulomb and surface effects. We find that the phase-coexistence model gives a reasonable description of the densities in the clusters and in the gas, but the precision is not high enough to obtain the correct proton fraction at low baryon densities. We also discuss the surface tension and neutron skin obtained within the energy minimization.

  16. Lonely Ladies

    E-Print Network [OSTI]

    Hacker, Randi; Tsutsui, William

    2006-07-19T23:59:59.000Z

    Broadcast Transcript: Lee Yu-jin sleeps with a "guy pillow" shaped like half a man's torso with one arm inexplicably encased in the sleeve of a blue dress shirt. Hong Yun-jeong confides in Dori-Dori, a little doll that ...

  17. A Study of Interstellar Gas and Stars in the Gravitationally Lensed Galaxy `The Cosmic Eye' from Rest-Frame Ultraviolet Spectroscopy

    E-Print Network [OSTI]

    Quider, Anna M; Pettini, Max; Steidel, Charles C; Stark, Daniel P

    2009-01-01T23:59:59.000Z

    We report the results of a study of the rest-frame UV spectrum of the Cosmic Eye, a luminous Lyman break galaxy at z=3.07331 gravitationally lensed by a factor of 25. The spectrum, recorded with the ESI spectrograph on the Keck II telescope, is rich in absorption features from the gas and massive stars in this galaxy. The interstellar absorption lines are resolved into two components of approximately equal strength and each spanning several hundred km/s in velocity. One component has a net blueshift of -70 km/s relative to the stars and H II regions and presumably arises in a galaxy-scale outflow similar to those seen in most star-forming galaxies at z = 2-3. The other is more unusual in showing a mean redshift of +350 km/s relative to the systemic redshift; possible interpretations include a merging clump, or material ejected by a previous star formation episode and now falling back onto the galaxy, or more simply a chance alignment with a foreground galaxy. In the metal absorption lines, both components onl...

  18. Super Massive Star Clusters: From Superwinds to a Cooling Catastrophe and the Re-processing of the Injected Gas

    E-Print Network [OSTI]

    Silich, S; Muñoz-Tunón, C; Palous, J

    2006-01-01T23:59:59.000Z

    Different hydrodynamic regimes for the gaseous outflows generated by multiple supernovae explosions and stellar winds occurring within compact and massive star clusters are discussed. It is shown that there exists the threshold energy that separates clusters whose outflows evolve in the quasi-adiabatic or radiative regime from those within which catastrophic cooling and a positive feedback star-forming mode sets in. The role of the surrounding ISM and the observational appearance of the star cluster winds evolving in different hydrodynamic regimes are also discussed.

  19. Questar Gas- Home Builder Gas Appliance Rebate Program

    Broader source: Energy.gov [DOE]

    Questar Gas provides incentives for home builders to construct energy efficient homes. Rebates are provided for both energy efficient gas equipment and whole home Energy Star certification. All...

  20. Ligand Lone-Pair Influence on Hydrocarbon C-H Activation: A Computational Perspective

    SciTech Connect (OSTI)

    Ess, Daniel H; Gunnoe, T. Brent; Cundari, Thomas R; Goddard, William A; Periana, Roy A

    2010-01-01T23:59:59.000Z

    Mid to late transition metal complexes that break hydrocarbon C?H bonds by transferring the hydrogen to a heteroatom ligand while forming a metal?alkyl bond offer a promising strategy for C?H activation. Here we report a density functional (B3LYP, M06, and X3LYP) analysis of cis-(acac){sub 2}MX and TpM(L)X (M = Ir, Ru, Os, and Rh; acac = acetylacetonate, Tp = tris(pyrazolyl)borate; X = CH{sub 3}, OH, OMe, NH{sub 2}, and NMe{sub 2}) systems for methane C?H bond activation reaction kinetics and thermodynamics. We address the importance of whether a ligand lone pair provides an intrinsic kinetic advantage through possible electronic d{sub ?}?p{sub ?} repulsions for M?OR and M?NR{sub 2} systems versus M?CH{sub 3} systems. This involves understanding the energetic impact of the X ligand group on ligand loss, C?H bond coordination, and C?H bond cleavage steps as well as understanding how the nucleophilicity of the ligand X group, the electrophilicity of the transition metal center, and cis-ligand stabilization effect influence each of these steps. We also explore how spectator ligands and second- versus third-row transition metal centers impact the energetics of each of these C?H activation steps.

  1. Evaluation and Demonstration of BMPs for Cattle on Grazing Lands for the Lone Star Healthy Streams Program

    E-Print Network [OSTI]

    Wagner, K.; Redmon, L.; Gentry, T.; Clary, C.

    dissemination ........................................................... 8 Subtask 1.7 Oversight of the LSHS Project Steering Committee .......................................................... 9 Subtask 1.8 Development of the final project report... all work performed under this project including technical and financial supervision and preparation of status reports. Subtask 1.1: Preparation of quarterly progress reports TWRI prepared and submitted Quarterly Progress Reports which can be viewed...

  2. The Molecular Gas Environment around Two Herbig Ae/Be Stars: Resolving the Outflows of LkHa 198 and LkHa 225S

    E-Print Network [OSTI]

    Brenda C. Matthews; James R. Graham; Marshall D. Perrin; Paul Kalas

    2007-08-13T23:59:59.000Z

    Observations of outflows associated with pre-main-sequence stars reveal details about morphology, binarity and evolutionary states of young stellar objects. We present molecular line data from the Berkeley-Illinois-Maryland Association array and Five Colleges Radio Astronomical Observatory toward the regions containing the Herbig Ae/Be stars LkHa 198 and LkHa 225S. Single dish observations of 12CO 1-0, 13CO 1-0, N2H+ 1-0 and CS 2-1 were made over a field of 4.3' x 4.3' for each species. 12CO data from FCRAO were combined with high resolution BIMA array data to achieve a naturally-weighted synthesized beam of 6.75'' x 5.5'' toward LkHa 198 and 5.7'' x 3.95'' toward LkHa 225S, representing resolution improvements of factors of approximately 10 and 5 over existing data. By using uniform weighting, we achieved another factor of two improvement. The outflow around LkHa 198 resolves into at least four outflows, none of which are centered on LkHa 198-IR, but even at our resolution, we cannot exclude the possibility of an outflow associated with this source. In the LkHa 225S region, we find evidence for two outflows associated with LkHa 225S itself and a third outflow is likely driven by this source. Identification of the driving sources is still resolution-limited and is also complicated by the presence of three clouds along the line of sight toward the Cygnus molecular cloud. 13CO is present in the environments of both stars along with cold, dense gas as traced by CS and (in LkHa 225S) N2H+. No 2.6 mm continuum is detected in either region in relatively shallow maps compared to existing continuum observations.

  3. Large-scale shock-ionized and photo-ionized gas in M83: the impact of star formation

    E-Print Network [OSTI]

    Hong, Sungryong; Dopita, Michael A; Blair, William P; Whitmore, Bradley C; Balick, Bruce; Bond, Howard E; Carollo, Marcella; Disney, Michael J; Frogel, Jay A; Hall, Donald; Holtzman, Jon A; Kimble, Randy A; McCarthy, Patrick J; O'Connell, Robert W; Paresce, Francesco; Saha, Abhijit; Silk, Joseph I; Trauger, John T; Walker, Alistair R; Windhorst, Rogier A; Young, Erick T; Mutchler, Max

    2011-01-01T23:59:59.000Z

    We investigate the ionization structure of the nebular gas in M83 using the line diagnostic diagram, [O III](5007 \\degA)/H{\\beta} vs. [S II](6716 \\deg A+6731 \\deg A)/H{\\alpha} with the newly available narrowband images from the Wide Field Camera 3 (WFC3) of the Hubble Space Telescope (HST). We produce the diagnostic diagram on a pixel-by-pixel (0.2" x 0.2") basis and compare it with several photo- and shock-ionization models. For the photo-ionized gas, we observe a gradual increase of the log([O III]/H{\\beta}) ratios from the center to the spiral arm, consistent with the metallicity gradient, as the H II regions go from super solar abundance to roughly solar abundance from the center out. Using the diagnostic diagram, we separate the photo-ionized from the shock-ionized component of the gas. We find that the shock-ionized H{\\alpha} emission ranges from ~2% to about 15-33% of the total, depending on the separation criteria used. An interesting feature in the diagnostic diagram is an horizontal distribution aro...

  4. LARGE-SCALE SHOCK-IONIZED AND PHOTOIONIZED GAS IN M83: THE IMPACT OF STAR FORMATION

    SciTech Connect (OSTI)

    Hong, Sungryong; Calzetti, Daniela [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Dopita, Michael A. [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia); Blair, William P. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Whitmore, Bradley C.; Bond, Howard E. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Balick, Bruce [Department of Astronomy, University of Washington, Seattle, WA 98195-1580 (United States); Carollo, Marcella [Department of Physics, ETH-Zurich, Zurich 8093 (Switzerland); Disney, Michael J. [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Frogel, Jay A. [Association of Universities for Research in Astronomy, Washington, DC 20005 (United States); Hall, Donald [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Holtzman, Jon A. [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Kimble, Randy A. [NASA-Goddard Space Flight Center, Greenbelt, MD 20771 (United States); McCarthy, Patrick J. [Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101-1292 (United States); O'Connell, Robert W. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Paresce, Francesco [Istituto di Astrofisica Spaziale e Fisica Cosmica, INAF, Via Gobetti 101, 40129 Bologna (Italy); Saha, Abhijit [National Optical Astronomy Observatories, Tucson, AZ 85726-6732 (United States); Silk, Joseph I. [Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Trauger, John T. [NASA-Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Walker, Alistair R., E-mail: wpb@pha.jhu.edu [Cerro Tololo Inter-American Observatory, La Serena (Chile)

    2011-04-10T23:59:59.000Z

    We investigate the ionization structure of the nebular gas in M83 using the line diagnostic diagram, [O III](5007 A)/H{beta} versus [S II](6716 A+6731 A)/H{alpha}, with the newly available narrowband images from the Wide Field Camera 3 (WFC3) of the Hubble Space Telescope (HST). We produce the diagnostic diagram on a pixel-by-pixel (0.''2 x 0.''2) basis and compare it with several photo- and shock-ionization models. We select four regions from the center to the outer spiral arm and compare them in the diagnostic diagram. For the photoionized gas, we observe a gradual increase of the log ([O III]/H{beta}) ratios from the center to the spiral arm, consistent with the metallicity gradient, as the H II regions go from super-solar abundance to roughly solar abundance from the center out. Using the diagnostic diagram, we separate the photoionized from the shock-ionized component of the gas. We find that the shock-ionized H{alpha} emission ranges from {approx}2% to about 15%-33% of the total, depending on the separation criteria used. An interesting feature in the diagnostic diagram is a horizontal distribution around log ([O III]/H{beta}) {approx} 0. This feature is well fit by a shock-ionization model with 2.0 Z{sub sun} metallicity and shock velocities in the range of 250-350 km s{sup -1}. A low-velocity shock component, <200 km s{sup -1}, is also detected and is spatially located at the boundary between the outer ring and the spiral arm. The low-velocity shock component can be due to (1) supernova remnants located nearby, (2) dynamical interaction between the outer ring and the spiral arm, and (3) abnormal line ratios from extreme local dust extinction. The current data do not enable us to distinguish among those three possible interpretations. Our main conclusion is that, even at the HST resolution, the shocked gas represents a small fraction of the total ionized gas emission at less than 33% of the total. However, it accounts for virtually all of the mechanical energy produced by the central starburst in M83.

  5. Spectro-interferometry of the Be star delta Sco: Near-Infrared Continuum and Gas Emission Region Sizes in 2007

    E-Print Network [OSTI]

    Millan-Gabet, R; Touhami, Y; Gies, D; Hesselbach, E; Pedretti, E; Thureau, N; Zhao, M; Brummelaar, T ten

    2010-01-01T23:59:59.000Z

    We present near-infrared H and K-band spectro-interferometric observations of the gaseous disk around the primary Be star in the delta Sco binary system, obtained in 2007 (between periastron passages in 2000 and 2011). Observations using the CHARA/MIRC instrument at H-band resolve an elongated disk with a Gaussian FWHM 1.18 x 0.91 mas. Using the Keck Interferometer, the source of the K-band continuum emission is only marginally spatially resolved, and consequently we estimate a relatively uncertain K-band continuum disk FWHM of 0.7 +/- 0.3 mas. Line emission on the other hand, He1 (2.0583 micron) and Br gamma (2.1657 micron), is clearly detected, with about 10% lower visibilities than those of the continuum. When taking into account the continuum/line flux ratio this translates into much larger sizes for the line emission regions: 2.2 +/- 0.4 mas and 1.9 +/- 0.3 mas for He1 and Br gamma respectively. Our KI data also reveal a relatively flat spectral differential phase response, ruling out significant off-cen...

  6. Excavation of the first stars

    E-Print Network [OSTI]

    Toshikazu Shigeyama; Takuji Tsujimoto; Yuzuru Yoshii

    2003-02-17T23:59:59.000Z

    The external pollution of the first stars in the Galaxy is investigated. The first stars were born in clouds composed of the pristine gas without heavy elements. These stars accreted gas polluted with heavy elements while they still remained in the cloud. As a result, it is found that they exhibit a distribution with respect to the surface metallicity. We have derived the actual form of this distribution function. This metallicity distribution function strongly suggests that the recently discovered most metal-deficient star HE0107-5240 with [Fe/H]=-5.3 was born as a metal-free star and accreted gas polluted with heavy elements. Thus the heavy elements such as Fe in HE0107-5240 must have been supplied from supernovae of later generations exploding inside the cloud in which the star had been formed. The elemental abundance pattern on the surface of stars suffering from such an external pollution should not be diverse but exhibit the average pattern of numerous supernovae. Future observations for a number of metal-deficient stars with [Fe/H]<-5 will be able to prove or disprove this external pollution scenario. Other possibilities to produce a star with this metallicity are also discussed.

  7. Efficiencies of Low-Mass Star and Star Cluster Formation

    E-Print Network [OSTI]

    Christopher D. Matzner; Christopher F. McKee

    2000-07-25T23:59:59.000Z

    Using a quantitative model for bipolar outflows driven by hydromagnetic protostellar winds, we calculate the efficiency of star formation assuming that available gas is either converted into stars or ejected in outflows. We estimate the efficiency of a single star formation event in a protostellar core, finding 25%-70% for cores with various possible degrees of flattening. The core mass function and the stellar initial mass function have similar slopes, because the efficiency is not sensitive to its parameters. We then consider the disruption of gas from a dense molecular clump in which a cluster of young stars is being born. In both cases, we present analytical formulae for the efficiencies that compare favorably against observations and, for clusters, against numerical simulations. We predict efficiencies in the range 30%-50% for the regions that form clusters of low-mass stars. In our model, star formation and gas dispersal happen concurrently. We neglect the destructive effects of massive stars: our results are therefore upper limits to the efficiency in regions more massive than about 3000 Msun.

  8. Economics of residential gas furnaces and water heaters in United States new construction market

    E-Print Network [OSTI]

    Lekov, Alex B.

    2010-01-01T23:59:59.000Z

    Experiences of residential consumers and utilities. OakStar (2008). Energy Star Residential Water Heaters: Finalefficiency improvements for residential gas furnaces in the

  9. Economics of residential gas furnaces and water heaters in US new construction market

    E-Print Network [OSTI]

    Lekov, Alex B.; Franco, Victor H.; Wong-Parodi, Gabrielle; McMahon, James E.; Chan, Peter

    2010-01-01T23:59:59.000Z

    appliance_standards/residential/water_ pool_heaters_prelim_Star (2008). Energy star residential water heaters: Finalefficiency improvements for residential gas furnaces in the

  10. PECO Energy (Gas) – Heating Efficiency Rebate Program

    Broader source: Energy.gov [DOE]

    The PECO Smart Gas Efficiency Upgrade Program offers rebates and incentives to commercial or residential customers that install an ENERGY STAR qualified high-efficiency natural gas furnace or...

  11. Star Wreck

    E-Print Network [OSTI]

    Alexander Kusenko; Mikhail Shaposhnikov; P. G. Tinyakov; Igor I. Tkachev

    1998-02-03T23:59:59.000Z

    Electroweak models with low-energy supersymmetry breaking predict the existence of stable non-topological solitons, Q-balls, that can be produced in the early universe. The relic Q-balls can accumulate inside a neutron star and gradually absorb the baryons into the scalar condensate. This causes a slow reduction in the mass of the star. When the mass reaches a critical value, the neutron star becomes unstable and explodes. The cataclysmic destruction of the distant neutron stars may be the origin of the gamma-ray bursts.

  12. OBSERVATIONS OF Arp 220 USING HERSCHEL-SPIRE: AN UNPRECEDENTED VIEW OF THE MOLECULAR GAS IN AN EXTREME STAR FORMATION ENVIRONMENT

    SciTech Connect (OSTI)

    Rangwala, Naseem; Maloney, Philip R.; Glenn, Jason; Kamenetzky, Julia [Center for Astrophysics and Space Astronomy, University of Colorado, 1255 38th street, Boulder, CO 80303 (United States); Wilson, Christine D.; Mentuch, Erin; Schirm, Maximilien R. P. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada); Rykala, Adam [School of Physics and Astronomy, Cardiff University, Queens Buildings The Parade, Cardiff CF24 3AA (United Kingdom); Isaak, Kate [ESA Astrophysics Missions Division, ESTEC, PO Box 299, 2200 AG Noordwijk (Netherlands); Baes, Maarten [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Bendo, George J. [UK ALMA Regional Centre Node, Jordell Bank Center for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Boselli, Alessandro [Laboratoire d'Astrophysique de Marseille, UMR6110 CNRS, 38 rue F. Joliot-Curie, F-13388 Marseille (France); Bradford, Charles M. [JPL, Pasadena, CA 91109 (United States); Clements, D. L. [Astrophysics Group, Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Cooray, Asantha [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Fulton, Trevor; Imhof, Peter [Blue Sky Spectroscopy Inc, Suite 9-740 4th Avenue South, Lethbridge, Alberta T1J 0N9 (Canada); Madden, Suzanne C.; Sauvage, Marc [CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Sacchi, Nicola [Istituto di Fisica dello Spazio Interplanetario, INAF, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); and others

    2011-12-10T23:59:59.000Z

    We present Herschel Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (Herschel SPIRE-FTS) observations of Arp 220, a nearby ultra-luminous infrared galaxy. The FTS provides continuous spectral coverage from 190 to 670 {mu}m, a wavelength region that is either very difficult to observe or completely inaccessible from the ground. The spectrum provides a good measurement of the continuum and detection of several molecular and atomic species. We detect luminous CO (J = 4-3 to 13-12) and water rotational transitions with comparable total luminosity {approx}2 Multiplication-Sign 10{sup 8} L{sub Sun }; very high-J transitions of HCN (J = 12-11 to 17-16) in absorption; strong absorption features of rare species such as OH{sup +}, H{sub 2}O{sup +}, and HF; and atomic lines of [C I] and [N II]. The modeling of the continuum shows that the dust is warm, with T = 66 K, and has an unusually large optical depth, with {tau}{sub dust} {approx} 5 at 100 {mu}m. The total far-infrared luminosity of Arp 220 is L{sub FIR} {approx} 2 Multiplication-Sign 10{sup 12} L{sub Sun }. Non-LTE modeling of the extinction corrected CO rotational transitions shows that the spectral line energy distribution of CO is fit well by two temperature components: cold molecular gas at T {approx} 50 K and warm molecular gas at T {approx} 1350{sup +280}{sub -100} K (the inferred temperatures are much lower if CO line fluxes are not corrected for dust extinction). These two components are not in pressure equilibrium. The mass of the warm gas is 10% of the cold gas, but it dominates the CO luminosity. The ratio of total CO luminosity to the total FIR luminosity is L{sub CO}/L{sub FIR} {approx} 10{sup -4} (the most luminous lines, such as J = 6-5, have L{sub CO,J=6-5}/L{sub FIR} {approx} 10{sup -5}). The temperature of the warm gas is in excellent agreement with the observations of H{sub 2} rotational lines. At 1350 K, H{sub 2} dominates the cooling ({approx}20 L{sub Sun} M{sup -1}{sub Sun }) in the interstellar medium compared to CO ({approx}0.4 L{sub Sun} M{sup -1}{sub Sun }). We have ruled out photodissociation regions, X-ray-dominated regions, and cosmic rays as likely sources of excitation of this warm molecular gas, and found that only a non-ionizing source can heat this gas; the mechanical energy from supernovae and stellar winds is able to satisfy the large energy budget of {approx}20 L{sub Sun} M{sup -1}{sub Sun }. Analysis of the very high-J lines of HCN strongly indicates that they are solely populated by infrared pumping of photons at 14 {mu}m. This mechanism requires an intense radiation field with T > 350 K. We detect a massive molecular outflow in Arp 220 from the analysis of strong P Cygni line profiles observed in OH{sup +}, H{sub 2}O{sup +}, and H{sub 2}O. The outflow has a mass {approx}> 10{sup 7} M{sub Sun} and is bound to the nuclei with velocity {approx}< 250 km s{sup -1}. The large column densities observed for these molecular ions strongly favor the existence of an X-ray luminous AGN (10{sup 44} erg s{sup -1}) in Arp 220.

  13. Electron lone pair distortion facilitated metal-insulator transition in ?-Pb{sub 0.33}V{sub 2}O{sub 5} nanowires

    SciTech Connect (OSTI)

    Wangoh, L.; Quackenbush, N. F. [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Marley, P. M.; Banerjee, S. [Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260 (United States); Sallis, S. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States); Fischer, D. A.; Woicik, J. C. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Piper, L. F. J., E-mail: lpiper@binghamton.edu [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-05-05T23:59:59.000Z

    The electronic structure of ?-Pb{sub 0.33}V{sub 2}O{sub 5} nanowires has been studied with x-ray photoelectron spectroscopy techniques. The recent synthesis of defect-free ?-Pb{sub 0.33}V{sub 2}O{sub 5} nanowires resulted in the discovery of an abrupt voltage-induced metal insulator transition. First principle calculations predicted an additional V-O-Pb hybridized “in-gap” state unique to this vanadium bronze playing a significant role in facilitating the transition. We confirm the existence, energetic position, and orbital character of the “in-gap” state. Moreover, we reveal that this state is a hybridized Pb 6s–O 2p antibonding lone pair state resulting from the asymmetric coordination of the Pb{sup 2+} ions.

  14. Gas & Galaxy Evolution ASP Conference Series, Vol. **VOLUME**, 2000

    E-Print Network [OSTI]

    Mihos, Chris

    Gas & Galaxy Evolution ASP Conference Series, Vol. **VOLUME**, 2000 J. E. Hibbard, M. P. Rupen and J. H. van Gorkom, eds. Gas/Star O#11;sets in Tidal Tails J. C. Mihos Case Western Reserve University, Cleveland, OH 44106 Abstract. We use numerical simulations to study the development of gas/star o#11;sets

  15. Feedback from Protostellar Outflows in Star and Star Cluster Formation

    E-Print Network [OSTI]

    Christopher D. Matzner

    2000-07-13T23:59:59.000Z

    Magnetic stresses collimate protostellar winds into a common distribution of force with angle. Sweeping into the ambient medium, such winds drive bipolar molecular outflows whose properties are insensitive to the distribution of ambient gas and to the details of how the wind is launched, and how its intensity varies over time. Moreover, these properties are in accord with the commonly observed features of outflows. This model is simple enough to permit a quantitative study of the feedback effects from low-mass star formation. It predicts the rate at which star-forming gas is ejected by winds, and hence the efficiency with which stars form. Applied to individual star formation, it relates the stellar initial mass function to the distribution of pre-stellar cores. Applied to cluster formation, it indicates whether the resulting stellar system will remain gravitationally bound. Using the energy injection and mass ejection implied by this model, we investigate the dynamical evolution of a molecular clump as a stellar cluster forms within it. This depends critically on the rate at which turbulence decays: it may involve equilibrium star formation (slow decay), overstable oscillations, or collapse (fast decay).

  16. RHIC | STAR Detector

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    about the collision. STAR TPC The Heart of STAR STAR's "heart" is the Time Projection Chamber which tracks and identifies particles emerging from heavy ion collisions. As each...

  17. Boson stars: Chemical potential and quark condensates

    E-Print Network [OSTI]

    Jitesh R. Bhatt; V. Sreekanth

    2010-05-06T23:59:59.000Z

    We study the properties of a star made of self-gravitating bosons gas in a mean-field approximation. A generalized set of Tolman-Oppenheimer-Volkov(TOV) equations is derived to incorporate the effect of chemical-potential in the general relativistic frame work. The metric-dependence of the chemical-potential gives a new class of solutions for the boson stars. It is demonstrated that the maximum mass and radius of the star change in a significant way when the effect of finite chemical-potential is considered. We also discuss the case of a boson star made of quark-condensates. It is found that when the self-interaction between the condensates is small as compared to their mass, the typical density is too high to form a diquark-boson star. Our results indicate that the star of quark-condensate may be formed in a low-density and high-pressure regime.

  18. Cold Gas in Cluster Cores

    E-Print Network [OSTI]

    Megan Donahue

    2006-11-26T23:59:59.000Z

    I review the literature's census of the cold gas in clusters of galaxies. Cold gas here is defined as the gas that is cooler than X-ray emitting temperatures (~10^7 K) and is not in stars. I present new Spitzer IRAC and MIPS observations of Abell 2597 (PI: Sparks) that reveal significant amounts of warm dust and star formation at the level of 5 solar masses per year. This rate is inconsistent with the mass cooling rate of 20 +/- 5 solar masses per year inferred from a FUSE [OVI] detection.

  19. Chameleon stars

    SciTech Connect (OSTI)

    Dzhunushaliev, Vladimir [Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Folomeev, Vladimir [Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Singleton, Douglas [Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Physics Department, CSU Fresno, Fresno, California 93740-8031 (United States)

    2011-10-15T23:59:59.000Z

    We consider a gravitating spherically symmetric configuration consisting of a scalar field nonminimally coupled to ordinary matter in the form of a perfect fluid. For this system we find static, regular, asymptotically flat solutions for both relativistic and nonrelativistic cases. It is shown that the presence of the nonminimal interaction leads to substantial changes both in the radial matter distribution of the star and in the star's total mass. A simple stability test indicates that, for the choice of parameters used in the paper, the solutions are unstable.

  20. Triggered star formation in the Magellanic Clouds

    E-Print Network [OSTI]

    B. G. Elmegreen; J. Palous; Kenji Bekki

    2006-01-01T23:59:59.000Z

    Abstract. We discuss how tidal interaction between the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), and the Galaxy triggers galaxy-wide star formation in the Clouds for the last ? 0.2 Gyr based on our chemodynamical simulations on the Clouds. Our simulations demonstrate that the tidal interaction induces the formation of asymmetric spiral arms with high gas densities and consequently triggers star formation within the arms in the LMC. Star formation rate in the present LMC is significantly enhanced just above the eastern edge of the LMC’s stellar bar owing to the tidal interaction. The location of the enhanced star formation is very similar to the observed location of 30 Doradus, which suggests that the formation of 30 Doradus is closely associated with the last Magellanic collision about 0.2 Gyr ago. The tidal interaction can dramatically compress gas initially within the outer part of the SMC so that new stars can be formed from the gas to become intergalactic young stars in the inter-Cloud region (e.g., the Magellanic Bridge). The metallicity distribution function of the newly formed stars in the Magellanic Bridge has a peak of [Fe/H] ? ?0.8, which is significantly lower than the stellar metallicity of the SMC.

  1. STAR FORMATION IN NUCLEAR RINGS OF BARRED GALAXIES

    SciTech Connect (OSTI)

    Seo, Woo-Young; Kim, Woong-Tae, E-mail: seowy@astro.snu.ac.kr, E-mail: wkim@astro.snu.ac.kr [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2013-06-01T23:59:59.000Z

    Nuclear rings in barred galaxies are sites of active star formation. We use hydrodynamic simulations to study the temporal and spatial behavior of star formation occurring in nuclear rings of barred galaxies where radial gas inflows are triggered solely by a bar potential. The star formation recipes include a density threshold, an efficiency, conversion of gas to star particles, and delayed momentum feedback via supernova explosions. We find that the star formation rate (SFR) in a nuclear ring is roughly equal to the mass inflow rate to the ring, while it has a weak dependence on the total gas mass in the ring. The SFR typically exhibits a strong primary burst followed by weak secondary bursts before declining to very small values. The primary burst is associated with the rapid gas infall to the ring due to the bar growth, while the secondary bursts are caused by re-infall of the ejected gas from the primary burst. While star formation in observed rings persists episodically over a few Gyr, the duration of active star formation in our models lasts for only about half of the bar growth time, suggesting that the bar potential alone is unlikely to be responsible for gas supply to the rings. When the SFR is low, most star formation occurs at the contact points between the ring and the dust lanes, leading to an azimuthal age gradient of young star clusters. When the SFR is large, on the other hand, star formation is randomly distributed over the whole circumference of the ring, resulting in no apparent azimuthal age gradient. Since the ring shrinks in size with time, star clusters also exhibit a radial age gradient, with younger clusters found closer to the ring. The cluster mass function is well described by a power law, with a slope depending on the SFR. Giant gas clouds in the rings have supersonic internal velocity dispersions and are gravitationally bound.

  2. Star Power

    ScienceCinema (OSTI)

    None

    2014-11-18T23:59:59.000Z

    The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.

  3. Star Power

    SciTech Connect (OSTI)

    None

    2014-10-17T23:59:59.000Z

    The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.

  4. The first stars: Where did they form?

    E-Print Network [OSTI]

    Jordi Miralda-Escude

    1999-12-15T23:59:59.000Z

    Several emerging links between high-redshift observational cosmology and the Galactic fossil evidence found in the kinematics, metallicities and ages of Milky Way stars are discussed. In a flat Cold Dark Matter model with $\\Omega\\simeq 0.3$ that agrees with present large-scale structure observations, the oldest stars in the Milky Way should have formed in the first halos where gas was able to cool, at $z\\simeq 20$. These earliest, weakly bound dwarf galaxies probably turned only a small fraction of their gas to stars, which should be metal-poor. However, the merging rate in the early universe was much faster than the present one, so massive halos with more efficient star formation and metallicities up to the highest values present today in the bulge could have formed less than $10^9$ years after the oldest stars. The mean metallicity produced in the universe by a given redshift is related to the mean surface brightness of star-forming galaxies above this redshift, and also to the reionization epoch if galaxies were the dominant sources of ionizing radiation. The biased distribution of the early dwarf galaxies where the first stars formed should result in an age gradient with radius of the low-metallicity stars in the Milky Way, with the oldest ones concentrated in the bulge and the youngest in the outer halo.

  5. Stereo-Active Lone-Pair Control on the Ferromagnetic Behavior in VO(SeO2OH)2:A new acentric ferromagnetic material

    SciTech Connect (OSTI)

    Kim, Sang-Hwan [University of Houston, Houston; Yeon, J [University of Houston, Houston; Safa-Sefat, Athena [ORNL; Mandrus, David [ORNL; Halasyamani, P Shiv [University of Houston, Houston

    2010-01-01T23:59:59.000Z

    A new acentric ferromagnetic material, VO(SeO{sub 2}OH){sub 2}, has been synthesized and characterized by single crystal X-ray diffraction, second harmonic generation (SHG), and magnetization measurements. The crystal structure of VO(SeO{sub 2}OH){sub 2} consists of linear chains of corner-shared V{sup 4+}O{sub 6} octahedra that are connected by SeO{sub 2}OH groups. The material exhibits a weak SHG efficiency, comparable to {alpha}-SiO{sub 2}, and a ferromagnetic transition (T{sub C}) at 2.5 K with a saturated magnetic moment of 1.09 {mu}B per formula unit ({mu}B/FU). The origin of the ferromagnetism is explained by the suppression of the antiferromagnetic superexchange (SE) and supersuper-exchange (SSE) interactions in the intra-chain and inter-chain magnetic interactions, respectively. In addition, using first principles density functional theory (DFT) calculations, we show that the SSE interactions depend on the O(2)-Se{sup 4+}-O(3) angle. As we demonstrate, the stereoactive lone-pair on Se{sup 4+} is the driving force for the inter-chain ferromagnetic interactions.

  6. Energy Star

    E-Print Network [OSTI]

    Reihl, K.; Tullos, A.

    2012-01-01T23:59:59.000Z

    is a joint program of: ? U.S. Environmental Protection Agency (EPA) ? U.S. Department of Energy (DOE) ? Mission: ? ?Help us all save money and protect the environment through energy efficient products and practices.? ? History: ? 1992 ? Energy... Star Label introduced for energy-efficient products ? Expanded to include technical information & tools ? Website: www.energystar.gov ESL-KT-12-10-08 CATEE 2012: Clean Air Through Energy Efficiency Conference, Galveston, TX, October 9-11, 2012...

  7. Chemical Enrichment from Massive Stars in Starbursts

    E-Print Network [OSTI]

    Henry A. Kobulnicky

    1999-01-20T23:59:59.000Z

    The warm ionized gas in low-mass, metal-poor starforming galaxies is chemically homogeneous despite the prevalence of large H II regions which contain hundreds of evolved massive stars, supernovae, and Wolf-Rayet stars with chemically-enriched winds. Galaxies with large Wolf-Rayet star content are chemically indistinguishable from other vigorously star-forming galaxies. Furthermore, no significant localized chemical fluctuations are present in the vicinity of young star clusters, despite large expected chemical yields of massive stars. An ad-hoc fine-tuning of the release, dispersal and mixing of the massive star ejecta could give rise to the observed homogeneity, but a more probable explanation is that fresh ejecta from massive stars reside in a hard-to-observe hot or cold phase. In any case, the observed chemical homogeneity indicates that heavy elements which have already mixed with the warm interstellar medium (thus accessible to optical spectroscopy) are homogeneously dispersed over scales exceeding 1 kpc. Mixing of fresh ejecta with the surrounding warm ISM apparently requires longer than the lifetimes of typical H II regions (>10^7 yrs). The lack of observed localized chemical enrichments is consistent with a scenario whereby freshly-synthesized metals from massive stars are expelled into the halos of galaxies in a hot, 10^6 K phase by supernova-driven winds before they cool and ``rain'' back down upon the galaxy, creating gradual enrichments on spatial scales >1 kpc.

  8. New Mexico Gas Company- Residential Efficiency Programs

    Broader source: Energy.gov [DOE]

    The New Mexico Gas Company provides incentives for energy saving measures and improvements to residential homes. Rebates are available for adding insulation and for homes which attain Energy Star...

  9. A photoactive titanate with a stereochemically active Sn lone pair: Electronic and crystal structure of Sn{sub 2}TiO{sub 4} from computational chemistry

    SciTech Connect (OSTI)

    Burton, Lee A. [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath (United Kingdom)] [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath (United Kingdom); Walsh, Aron, E-mail: a.walsh@bath.ac.uk [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath (United Kingdom)] [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath (United Kingdom)

    2012-12-15T23:59:59.000Z

    TiO{sub 2} remains the most widely studied metal oxide for photocatalytic reactions. The standard approach to reduce the band gap of titania, for increasing the absorption of visible light, is anion modification. For example the formation of an oxynitride compound, where the nitrogen 2p states decrease the binding energy of the valence band. We demonstrate that cation modification can produce a similar effect through the formation of a ternary oxide combining Ti and an ns{sup 2} cation, Sn(II). In Sn{sub 2}TiO{sub 4}, the underlying Ti 3d conduction states remain largely unmodified and an electronic band gap of 2.1 eV (590 nm) is predicted by hybrid density functional theory. Our analysis indicates a strong potential for Sn{sub 2}TiO{sub 4} in visible-light driven photocatalysis, which should prove superior to the alternative (SnO{sub 2}){sub 1-x}(TiO{sub 2}){sub x} solid-solution. - Graphical abstract: Sn{sub 2}TiO{sub 4} is predicted to be a semiconductor with potential for bipolar conductivity and visible-light photocatalysis. Highlights: Black-Right-Pointing-Pointer Tin titanate adopts the Pb{sub 3}O{sub 4} crystal structure with a sterically active Sn(II) lone pair. Black-Right-Pointing-Pointer Tin titanate is thermodynamically stable with respect to TiO{sub 2} and SnO. Black-Right-Pointing-Pointer Tin titanate is predicted have a band gap of 590 nm, ideal for photocatalytic applications.

  10. STAR FORMATION IN TWO LUMINOUS SPIRAL GALAXIES

    SciTech Connect (OSTI)

    Hunter, Deidre A.; Ashburn, Allison; Wright, Teresa [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Elmegreen, Bruce G. [IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Rubin, Vera C. [Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Józsa, Gyula I. G.; Struve, Christian [ASTRON (Netherlands Organisation for Scientific Research NWO), Oude Hoogeveensedijk 4, 7991-PD Dwingeloo (Netherlands)

    2013-10-01T23:59:59.000Z

    We examined star formation in two very luminous (M{sub V} = –22 to –23) Sc-type spiral galaxies, NGC 801 and UGC 2885, using ultra-deep H? images. We combine these H? images with UBV and Two-Micron All-Sky Survey JHK images and H I maps to explore the star formation characteristics of disk galaxies at high luminosity. H? traces star formation in these galaxies to 4-6 disk scale lengths, but the lack of detection of H? further out is likely due to the loss of Lyman continuum photons. Considering gravitational instabilities alone, we find that the gas and stars in the outer regions are marginally stable in an average sense, but considering dissipative gas and radial and azimuthal forcing, the outer regions are marginally unstable to forming spiral arms. Star formation is taking place in spiral arms, which are regions of locally higher gas densities. Furthermore, we have traced smooth exponential stellar disks over four magnitudes in V-band surface brightness and 4-6 disk scale lengths, in spite of a highly variable gravitational instability parameter. Thus, gravitational instability thresholds do not seem relevant to the stellar disk. One possibility for creating an exponential disk is that the molecular cloud densities and star formation rates have exponential profiles and this fact forces the stellar disk to build up such a profile. Another possibility is that the stellar disk is continuously adjusted to an exponential shape regardless of the star formation profile, for example, through global dynamical processes that scatter stars. However, such scattering processes are only known to operate in spiral systems, in which case they cannot explain the same dilemma of smooth exponential disks observed in dwarf irregular galaxies.

  11. The Differential Lifetimes of Protostellar Gas and Dust Disks

    E-Print Network [OSTI]

    Taku Takeuchi; C. J. Clarke; D. N. C. Lin

    2005-03-22T23:59:59.000Z

    We construct a protostellar disk model that takes into account the combined effect of viscous evolution, photoevaporation and the differential radial motion of dust grains and gas. For T Tauri disks, the lifetimes of dust disks that are mainly composed of millimeter sized grains are always shorter than the gas disks' lifetimes, and become similar only when the grains are fluffy (density 10 AU), without strong signs of gas accretion nor of millimeter thermal emission from the dust. For Herbig AeBe stars, the strong photoevaporation clears the inner disks in 10^6 yr, before the dust grains in the outer disk migrate to the inner region. In this case, the grains left behind in the outer gas disk accumulate at the disk inner edge (at 10-100 AU from the star). The dust grains remain there even after the entire gas disk has been photoevaporated, and form a gas-poor dust ring similar to that observed around HR 4796A. Hence, depending on the strength of the stellar ionizing flux, our model predicts opposite types of products around young stars. For low mass stars with a low photoevaporation rate, dust-poor gas disks with an inner hole would form, whereas for high mass stars with a high photoevaporation rate, gas-poor dust rings would form. This prediction should be examined by observations of gas and dust around weak line T Tauri stars and evolved Herbig AeBe stars.

  12. Ionising stellar populations in circumnuclear star forming regions

    E-Print Network [OSTI]

    Enrique Perez-Montero; Angeles I. Diaz; Marcelo Castellanos

    2004-11-10T23:59:59.000Z

    We present a study of the stellar populations and gas physical conditions in Circumnuclear Star Forming Regions (CNSFRs) based on spectrophotometric data, including the 7000 angstroms to 1 micron spectral range, which is of great interest to the whole diagnostic of the ionized gas. The properties of CNSFRs as a class are inferred from a comparison with those of other star forming emission-line objects: low excitation disc HII regions and HII galaxies.

  13. Spectral Modeling Hot Star Winds

    E-Print Network [OSTI]

    Cohen, David

    supernovaeProduce supernovae (neutron stars, black holes)(neutron stars, black holes) ·· Found near birth

  14. The Nature of OH/IR Stars in the Galactic Centre Region Joris Blommaert,

    E-Print Network [OSTI]

    Sjouwerman, Loránt

    The Nature of OH/IR Stars in the Galactic Centre Region Joris Blommaert, Sterrewacht Leiden, P, 439 92 Onsala, Sweden Abstract. We report on infrared observations of stars in a field of 30 0 near distinct populations of OH/IR stars near the galactic centre is addressed. The dust­to­gas mass loss ratio

  15. Cloud and Star Formation in Disk Galaxy Models with Feedback

    E-Print Network [OSTI]

    Rahul Shetty; Eve C. Ostriker

    2008-05-26T23:59:59.000Z

    We include feedback in global hydrodynamic simulations in order to study the star formation properties, and gas structure and dynamics, in models of galactic disks. We extend previous models by implementing feedback in gravitationally bound clouds: momentum is injected at a rate proportional to the star formation rate. This mechanical energy disperses cloud gas back into the surrounding ISM, truncating star formation in a given cloud, and raising the overall level of ambient turbulence. Propagating star formation can however occur as expanding shells collide, enhancing the density and triggering new cloud and star formation. By controlling the momentum injection per massive star and the specific star formation rate in dense gas, we find that the negative effects of high turbulence outweigh the positive ones, and in net feedback reduces the fraction of dense gas and thus the overall star formation rate. The properties of the large clouds that form are not, however, very sensitive to feedback, with cutoff masses of a few million solar masses, similar to observations. We find a relationship between the star formation rate surface density and the gas surface density with a power law index ~2 for our models with the largest dynamic range, consistent with theoretical expectations for our model of disk flaring. We point out that the value of the "Kennicutt-Schmidt" index depends on the thickness of the disk. With our simple feedback prescription (a single combined star formation event per cloud), we find that global spiral patterns are not sustained; less correlated feedback and smaller scale turbulence appear to be necessary for spiral patterns to persist.

  16. Star formation bursts in isolated spiral galaxies

    E-Print Network [OSTI]

    C. Clarke; D. Gittins

    2006-07-03T23:59:59.000Z

    We study the response of the gaseous component of a galactic disc to the time dependent potential generated by N-body simulations of a spiral galaxy. The results show significant variation of the spiral structure of the gas which might be expected to result in significant fluctuations in the Star Formation Rate (SFR). Pronounced local variations of the SFR are anticipated in all cases. Bursty histories for the global SFR, however, require that the mean surface density is much less (around an order of magnitude less) than the putative threshold for star formation. We thus suggest that bursty star formation histories, normally attributed to mergers and/or tidal interactions, may be a normal pattern for gas poor isolated spiral galaxies.

  17. Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

    E-Print Network [OSTI]

    Turner, J L; Benford, D J; Consiglio, S M; Ho, P T P; Kovács, A; Meier, D S; Zhao, J -H

    2015-01-01T23:59:59.000Z

    A local dwarf galaxy, NGC 5253, has a young super star cluster that may provide an example of highly efficient star formation. Here we report the detection and imaging, with the Submillimeter Array, of the J= 3-2 rotational transition of CO at the location of the massive cluster associated with the supernebula. The gas cloud is hot, dense, quiescent, and extremely dusty. Its gas-to-dust ratio is lower than the Galactic value, which we attribute to dust enrichment by Wolf-Rayet stars within the embedded star cluster. Its star formation efficiency exceeds 50%, ten times higher than clouds in the Milky Way: this cloud is a factory of stars and soot. We suggest that high efficiency results from the force-feeding of star formation by a streamer of gas falling into the galaxy.

  18. Compressed Gas EHS-2200-WEB

    E-Print Network [OSTI]

    Compressed Gas Safety EHS-2200-WEB Register and launch through http://axess.stanford.edu Course title and STARS number: General Safety & Emergency Preparedness EHS-4200-WEB Chemical Safety for Laboratories EHS-1900-WEB Biosafety EHS-1500-WEB Radiation Safety Training EHS-5250 Laser Safety EHS-4820-WEB

  19. Radiative feedback from ionized gas

    E-Print Network [OSTI]

    S. C. O. Glover

    2007-03-28T23:59:59.000Z

    H2 formation in metal-free gas occurs via the intermediate H- or H2+ ions. Destruction of these ions by photodissociation therefore serves to suppress H2 formation. In this paper, I highlight the fact that several processes that occur in ionized primordial gas produce photons energetic enough to photodissociate H- or H2+ and outline how to compute the photodissociation rates produced by a particular distribution of ionized gas. I also show that there are circumstances of interest, such as during the growth of HII regions around the first stars, in which this previously overlooked form of radiative feedback is of considerable importance.

  20. Economics of Condensing Gas Furnaces and Water Heaters Potential in Residential Single Family Homes

    E-Print Network [OSTI]

    Lekov, Alex

    2011-01-01T23:59:59.000Z

    Star Residential Water Heaters: Final criteria analysis.gas furnaces and water heaters in US new constructioncondensing furnace and water heater and the pay-back period

  1. Baltimore Gas and Electric Company (Electric)- Residential Energy Efficiency Rebate Program

    Broader source: Energy.gov [DOE]

    The Baltimore Gas and Electric Company (BGE) offers rebates for residential customers to improve the energy efficiency of eligible homes. Rebates are available for Energy Star clothes washers,...

  2. Molecular Gas in Galaxies

    E-Print Network [OSTI]

    F. Combes

    2000-07-21T23:59:59.000Z

    Knowledge of the molecular component of the ISM is fundamental to understand star formation. The H2 component appears to dominate the gas mass in the inner parts of galaxies, while the HI component dominates in the outer parts. Observation of the CO and other lines in normal and starburst galaxies have questioned the CO-to-H2 conversion factor, and detection of CO in dwarfs have shown how sensitive the conversion f actor is to metallicity. Our knowledge has made great progress in recent years, because of sensitivity and spatial resolution improvements. Large-scale CO maps of nearby galaxies are now available, which extend our knowledge on global properties, radial gradients, and spiral structure of the molecular ISM. Millimetric interferometers reveal high velocity gradients in galaxy nuclei, and formation of embedded structures, like bars within bars. Galaxy interactions are very effective to enhance gas concentrations and trigger starbursts. Nuclear disks or rings are frequently observed, that concentrate the star formation activity. Since the density of starbursting galaxies is strongly increasing with redshift, the CO lines and the mm dust emission are a privileged tool to follow evolution of galaxies and observe the ISM dynamics at high redshift: they could give an answer about the debated question of the star-formation history, since many massive remote starbursts could be dust-enshrouded.

  3. ULTRA-FAINT DWARF GALAXIES AS A TEST OF EARLY ENRICHMENT AND METALLICITY-DEPENDENT STAR FORMATION

    SciTech Connect (OSTI)

    Tassis, Konstantinos [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Gnedin, Nickolay Y. [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kravtsov, Andrey V. [Kavli Institute for Cosmological Physics and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)

    2012-01-20T23:59:59.000Z

    The close relation of star formation with molecular gas indicated by observations and assumed in recent models implies that the efficiency with which galaxies convert their gas into stars depends on gas metallicity. This is because abundance of molecular hydrogen is sensitive to abundance of dust, which catalyzes formation of H{sub 2} and helps to shield it from dissociating radiation. In this study, we point out that in the absence of significant pre-enrichment by Population III stars forming out of zero metallicity gas, such H{sub 2}-based star formation is expected to leave an imprint in the form of bi-modality in the metallicity distribution among dwarf galaxies and in the metallicity distribution of stars within individual galaxies. The bi-modality arises because when gas metallicity (and dust abundance) is low, formation of molecular gas is inefficient, the gas consumption timescale is long, and star formation and metal enrichment proceed slowly. When metallicity reaches a critical threshold value star formation and enrichment accelerate, which leads to rapid increase in both stellar mass and metallicity of galaxies. We demonstrate this process both using a simple analytical model and full cosmological simulations. In contrast, the observed metallicity distributions of dwarf galaxies or stars within them are not bi-modal. We argue that this discrepancy points to substantial early stochastic pre-enrichment by Population III stars to levels Z {approx} 10{sup -2} Z{sub Sun} in dense, star-forming regions of early galaxies.

  4. The Cosmological Context of Extraplanar Gas

    E-Print Network [OSTI]

    James Binney

    2004-09-27T23:59:59.000Z

    I review evidence that galaxies form from gas that falls into potential wells cold, rather than from virialized gas, and that formation stops once an atmosphere of trapped virialized gas has accumulated. Disk galaxies do not have such atmospheres, so their formation is ongoing. During galaxy formation feedback is an efficient process, and the nuclear regions of disk galaxies blow winds. The cold infalling gas that drives continued star formation has a significant component of angular momentum perpendicular to that of the disk. Extraplanar gas has to be understood in the context set by nuclear outflows and cold skew-rotating cosmic infall.

  5. Social networks for lonely objects

    E-Print Network [OSTI]

    Kestner, John Anthony

    2010-01-01T23:59:59.000Z

    Visions of ubiquitous computing describe a network of devices that quietly supports human goals, but this may also add complexity to an already frustrating relationship between humans and their electronic objects. As we ...

  6. Idaho_LonePinePeak

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh School footballHydrogenIT |Hot Springs Site #0104 Latitude:Peak Site

  7. Idaho_LonePineRidge

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh School footballHydrogenIT |Hot Springs Site #0104 Latitude:Peak

  8. Could the Ultra Metal-poor Stars be Chemically Peculiar and Not Related to the First Stars?

    E-Print Network [OSTI]

    K. A. Venn; D. L. Lambert

    2008-01-04T23:59:59.000Z

    Chemically peculiar stars define a class of stars that show unusual elemental abundances due to stellar photospheric effects and not due to natal variations. In this paper, we compare the elemental abundance patterns of the ultra metal-poor stars with metallicities [Fe/H] $\\sim -5 $ to those of a subclass of chemically peculiar stars. These include post-AGB stars, RV Tauri variable stars, and the Lambda Bootis stars, which range in mass, age, binarity, and evolutionary status, yet can have iron abundance determinations as low as [Fe/H] $\\sim -5$. These chemical peculiarities are interpreted as due to the separation of gas and dust beyond the stellar surface, followed by the accretion of dust depleted-gas. Contrary to this, the elemental abundances in the ultra metal-poor stars are thought to represent yields of the most metal-poor supernova and, therefore, observationally constrain the earliest stages of chemical evolution in the Universe. The abundance of the elements in the photospheres of the ultra metal-poor stars appear to be related to the condensation temperature of that element; if so, then their CNO abundances suggest true metallicities of [X/H]~ -2 to -4, rather than their present metallicities of [Fe/H] < -5.

  9. UNLEASHING POSITIVE FEEDBACK: LINKING THE RATES OF STAR FORMATION, SUPERMASSIVE BLACK HOLE ACCRETION, AND OUTFLOWS IN DISTANT GALAXIES

    SciTech Connect (OSTI)

    Silk, Joseph [Institut d'Astrophysique, UMR 7095 CNRS, Universite Pierre et Marie Curie, 98bis Blvd Arago, F-75014 Paris (France); Department of Physics and Astronomy, The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom)

    2013-08-01T23:59:59.000Z

    Pressure-regulated star formation is a simple variant on the usual supernova-regulated star formation efficiency that controls the global star formation rate as a function of cold gas content in star-forming galaxies, and accounts for the Schmidt-Kennicutt law in both nearby and distant galaxies. Inclusion of active galactic nucleus (AGN) induced pressure, by jets and/or winds that flow back onto a gas-rich disk, can lead, under some circumstances, to significantly enhanced star formation rates, especially at high redshift and most likely followed by the more widely accepted phase of star formation quenching. Simple expressions are derived that relate supermassive black hole growth, star formation, and outflow rates. The ratios of black hole to spheroid mass and of both black hole accretion and outflow rates to star formation rate are predicted as a function of time. I suggest various tests of the AGN-triggered star formation hypothesis.

  10. A single low-energy, iron-poor supernova as the source of metals in the star SMSS J031300.36?670839.3

    E-Print Network [OSTI]

    Keller, S. C.

    The element abundance ratios of four low-mass stars with extremely low metallicities (abundances of elements heavier than helium) indicate that the gas out of which the stars formed was enriched in each case by at most a ...

  11. ENRICHMENT OF THE DUST-TO-GAS MASS RATIO IN BONDI/JEANS ACCRETION/CLOUD SYSTEMS DUE TO UNEQUAL CHANGES IN DUST AND GAS INCOMING VELOCITIES

    E-Print Network [OSTI]

    Bellan, Paul M.

    ENRICHMENT OF THE DUST-TO-GAS MASS RATIO IN BONDI/JEANS ACCRETION/CLOUD SYSTEMS DUE TO UNEQUAL velocity profile from gas so that the dust-to-gas ratio is substantially enriched above the 1% interstellar of motion that the dust-to-gas ratio can become substantially enriched during Bondi- type accretion. Star

  12. Implications of modes of star formation for the overall dynamics of galactic disks

    E-Print Network [OSTI]

    B. Fuchs

    2001-03-22T23:59:59.000Z

    One of the present concepts for the onset of massive star formation is the Kennicutt criterion. This relates the onset of massive star formation to a general gravitational instability of the gas disks of spiral galaxies. It is often overlooked, however that such gravitational instabilities of the gas disks have severe implications for the overall stability of the gas and star disks of spiral galaxies. I show by numerical simulations of the evolution of a combined gas and star disk that the violation of the stability condition induces violent dynamical evolution of the combined system. In particular the star disk heats up on time scales less than a Gyr to unrealistic high values of the Toomre stability parameter Q. The morphologies of both the star and gas disk resemble then no longer observed morphologies of spiral galaxies. Star formation of stars on low velocity dispersion orbits would lead to dynamical cooling of the disks to more realistic states. However, the required star formation rate is extremely high.

  13. From Neutron Stars to Strange Stars

    E-Print Network [OSTI]

    Fridolin Weber

    2001-12-04T23:59:59.000Z

    This paper discusses several most intruigung astrophysical implications connected with the possible absolute stability of strange quark matter.This is followed by a discussion of two astrophysical signals that may point at the existence of quark matter in both isolated neutron stars as well as in neutron stars in low-mass x-ray binaries (LMXBs).

  14. On the extreme positive star-formation feedback condition in SCUBA sources

    E-Print Network [OSTI]

    Silich, S; Munoz-Tunon, C; Hueyotl-Zahuantitla, F; Wunsch, R; Palous, J

    2010-01-01T23:59:59.000Z

    We present a detailed study of the hydrodynamics of the matter reinserted by massive stars via stellar winds and supernovae explosions in young assembling galaxies. We show that the interplay between the thermalization of the kinetic energy provided by massive stars, radiative cooling of the thermalized plasma and the gravitational pull of the host galaxy, lead to three different hydrodynamic regimes. These are: a) The quasi-adiabatic supergalactic winds. b) The bimodal flows, with mass accumulation in the central zones and gas expulsion from the outer zones of the assembling galaxy. c) The gravitationally bound regime, for which all of the gas returned by massive stars remains bound to the host galaxy and is likely to be reprocessed into futher generations of stars. Which of the three possible solutions takes place, depends on the mass of the star forming region its mechanical luminosity (or star formation rate) and its size. The model predicts that massive assembling galaxies with large star formation rates...

  15. Massive stars and the energy balance of the ISM. I. The impact of an isolated 60 Msun star

    E-Print Network [OSTI]

    Tim Freyer; Gerhard Hensler; Harold W. Yorke

    2003-06-25T23:59:59.000Z

    We present results of numerical simulations carried out with a 2D radiation hydrodynamics code in order to study the impact of massive stars on their surrounding interstellar medium. This first paper deals with the evolution of the circumstellar gas around an isolated 60 Msun star. The interaction of the photoionized HII region with the stellar wind bubble forms a variety of interesting structures like shells, clouds, fingers, and spokes. These results demonstrate that complex structures found in HII regions are not necessarily relics from the time before the gas became ionized but may result from dynamical processes during the course of the HII region evolution. We have also analyzed the transfer and deposit of the stellar wind and radiation energy into the circumstellar medium until the star explodes as a supernova. Although the total mechanical wind energy supplied by the star is negligible compared to the accumulated energy of the Lyman continuum photons, the kinetic energy imparted to the circumstellar gas over the star's lifetime is 4 times higher than for a comparable windless simulation. Furthermore, the thermal energy of warm photoionized gas is lower by some 55%. Our results document the necessity to consider both ionizing radiation and stellar winds for an appropriate description of the interaction of OB stars with their circumstellar environment.

  16. Chemical Evolution of the Galactic Halo through Supernova-Induced Star Formation and Its Implication for Population III Stars

    E-Print Network [OSTI]

    Takuji Tsujimoto; Toshikazu Shigeyama; Yuzuru Yoshii

    1999-05-06T23:59:59.000Z

    A model for Galactic chemical evolution, driven by supernova-induced star formation, is formulated and used to examine the nature of the Galactic halo at early epochs. In this model, new stars are formed following each supernova event, thus their abundance pattern is determined by the combination of heavy elements ejected from the supernova itself and those elements which are already present in the interstellar gas swept up by the supernova remnant. The end result is a prediction of large scatter in the abundance ratios among low-metallicity stars, reflecting a different nucleosynthesis yield for each Type II supernova with a different progenitor mass. Formation of new stars is terminated when supernova remnants sweep up too little gas to form shells. We show from calculations based on the above scenario that (i) the observed [Fe/H] distribution for the Galactic halo field stars can be reproduced without effectively decreasing the heavy-element yields from Type II supernovae by some manipulation required by previous models (e.g., via mass loss from the early Galaxy, or later mixing with ``pristine'' hydrogen clouds), (ii) the large observed scatter in the abundance ratio [Eu/Fe] for the most metal-poor stars can also be reproduced, and (iii) the frequency distribution of stars in the [Eu/Fe]-[Fe/H] plane can be predicted. Our model suggests that the probability of identifying essentially metal-free stars (Population III) in the local halo is around one in 10^{3-4}, provided that star formation in the halo is confined to individual gas clouds with mass of 10^{6-7} Msun and that the initial mass function of metal-free stars is not significantly different from the Salpeter mass function.

  17. Precipitation-Regulated Star Formation in Galaxies

    E-Print Network [OSTI]

    Voit, G Mark; O'Shea, Brian W; Donahue, Megan

    2015-01-01T23:59:59.000Z

    Galaxy growth depends critically on the interplay between radiative cooling of cosmic gas and the resulting energetic feedback that cooling triggers. This interplay has proven exceedingly difficult to model, even with large supercomputer simulations, because of its complexity. Nevertheless, real galaxies are observed to obey simple scaling relations among their primary observable characteristics. Here we show that a generic emergent property of the interplay between cooling and feedback can explain the observed scaling relationships between a galaxy's stellar mass, its total mass, and its chemical enrichment level, as well as the relationship between the average orbital velocity of its stars and the mass of its central black hole. These relationships naturally result from any feedback mechanism that strongly heats a galaxy's circumgalactic gas in response to precipitation of colder clouds out of that gas, because feedback then suspends the gas in a marginally precipitating state.

  18. Star Formation in Mergers and Interacting Galaxies: Gathering the Fuel

    E-Print Network [OSTI]

    Curtis Struck

    2006-10-06T23:59:59.000Z

    Selected results from recent studies of star formation in galaxies at different stages of interaction are reviewed. Recent results from the Spitzer Space Telescope are highlighted. Ideas on how large-scale driving of star formation in interacting galaxies might mesh with our understanding of star formation in isolated galaxies and small scale mechanisms within galaxies are considered. In particular, there is evidence that on small scales star formation is determined by the same thermal and turbulent processes in cool compressed clouds as in isolated galaxies. If so, this affirms the notion that the primary role of large-scale dynamics is to gather and compress the gas fuel. In gas-rich interactions this is generally done with increasing efficiency through the merger process.

  19. Forming equatorial rings around dying stars

    E-Print Network [OSTI]

    Akashi, Muhammad; Yogev, Ohad; Soker, Noam

    2015-01-01T23:59:59.000Z

    We suggest that clumpy-dense outflowing equatorial rings around evolved giant stars, such as in supernova 1987A and the Necklace planetary nebula, are formed by bipolar jets that compress gas toward the equatorial plane. The jets are launched from an accretion disk around a stellar companion. Using the FLASH hydrodynamics numerical code we perform 3D numerical simulations, and show that bipolar jets expanding into a dense spherical shell can compress gas toward the equatorial plane and lead to the formation of an expanding equatorial ring. Rayleigh-Taylor instabilities in the interaction region break the ring to clumps. Under the assumption that the same ring-formation mechanism operates in massive stars and in planetary nebulae, we find this mechanism to be more promising for ring formation than mass loss through the second Lagrangian point. The jets account also for the presence of a bipolar nebula accompanying many of the rings.

  20. The Early Evolution of Massive Stars: Radio Recombination Line Spectra

    E-Print Network [OSTI]

    Eric Keto; Qizhou Zhang; Stanley Kurtz

    2007-11-15T23:59:59.000Z

    Velocity shifts and differential broadening of radio recombination lines are used to estimate the densities and velocities of the ionized gas in several hypercompact and ultracompact HII regions. These small HII regions are thought to be at their earliest evolutionary phase and associated with the youngest massive stars. The observations suggest that these HII regions are characterized by high densities, supersonic flows and steep density gradients, consistent with accretion and outflows that would be associated with the formation of massive stars.

  1. Helium preenrichment in the star-forming regions

    E-Print Network [OSTI]

    Leonid Chuzhoy

    2006-05-15T23:59:59.000Z

    We show that element diffusion can produce large fluctuations in the initial helium abundance of the star-forming clouds. Diffusion time-scale, which in stars is much larger than the Hubble time, can fall below 10^8 years in the neutral gas clouds dominated by collisionless dark matter or with dynamically important radiation or magnetic pressure. Helium diffusion may therefore explain the recent observations of globular clusters, which are inconsistent with initially homogeneous helium distribution.

  2. Massive stars vs. nebular abundances in the Orion nebula

    E-Print Network [OSTI]

    Sergio Simón Díaz

    2006-11-16T23:59:59.000Z

    The search of consistency between nebular and massive star abundances has been a longstanding problem. I briefly review what has been done regarding to this topic, also presenting a recent study focused on the Orion nebula: the O and Si stellar abundances resulting from a detailed and fully consistent spectroscopic analysis of the group of B stars associated with the Orion nebula are compared with the most recent nebular gas-phase results.

  3. Young star clusters in the circumnuclear region of NGC 2110

    SciTech Connect (OSTI)

    Durré, Mark; Mould, Jeremy, E-mail: mdurre@swin.edu.au [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122 (Australia)

    2014-03-20T23:59:59.000Z

    High-resolution observations in the near infrared show star clusters around the active galactic nucleus (AGN) of the Seyfert 1 NGC 2110, along with a 90 × 35 pc bar of shocked gas material around its nucleus. These are seen for the first time in our imaging and gas kinematics of the central 100 pc with the Keck OSIRIS instrument with adaptive optics. Each of these clusters is two to three times brighter than the Arches cluster close to the center of the Milky Way. The core star formation rate is 0.3 M {sub ?} yr{sup –1}. The photoionized gas (He I) dynamics imply an enclosed mass of 3-4 × 10{sup 8} M {sub ?}. These observations demonstrate the physical linkage between AGN feedback, which triggers star formation in massive clusters, and the resulting stellar (and supernovae) winds, which cause the observed [Fe II] emission and feed the black hole.

  4. magnitude larger than in star-forming galaxies. This all suggests a heating source other than stars and the AGN is the obvious

    E-Print Network [OSTI]

    Blake, Geoffrey

    magnitude larger than in star-forming galaxies. This all suggests a heating source other than stars and the AGN is the obvious alternative. Differential magni®cation of AGN-heated gas therefore seems-switching schemeÐare the cause of the extended CO emission, but we consider it to be remote. This is borne out

  5. Playing with positive feedback: external pressure-triggering of a star-forming disc galaxy

    E-Print Network [OSTI]

    Bieri, Rebekka; Silk, Joseph; Mamon, Gary A

    2015-01-01T23:59:59.000Z

    Feedback in massive galaxies generally involves quenching of star formation, a favored candidate being outflows from a central supermassive black hole. At high redshifts however, explanation of the huge rates of star formation often found in galaxies containing AGN may require a more vigorous mode of star formation than attainable by simply enriching the gas content of galaxies in the usual gravitationally-driven mode that is associated with the nearby Universe. Using hydrodynamical simulations, we demonstrate that AGN-pressure-driven star formation potentially provides the positive feedback that may be required to generate the accelerated star formation rates observed in the distant Universe.

  6. Analyze of the star formation modeling algorithm in SPH code

    E-Print Network [OSTI]

    Peter Berczik

    2001-06-06T23:59:59.000Z

    The chemical and photometric evolution of star forming disk galaxies is investigated. Numerical simulations of the complex gasdynamical flows are based on our own coding of the Chemo - Dynamical Smoothed Particle Hydrodynamical (CD - SPH) approach, which incorporates the effects of star formation. The presented model describes well the time evolution of the basic dynamical, chemical and photometric parameters of a disk galaxy similar to the Milky Way. The metallicity, luminosity and colors obtained are typical for such disk galaxies. During the calculations we made an extended test of the proposed SF criteria. We find that the obtained results with different "gas" and "star" particle numbers are not only qualitatively but also quantitatively similar.

  7. Circumnuclear Regions of Star Formation in Early Type Galaxies

    E-Print Network [OSTI]

    Diaz, Angeles I; Hagele, Guillermo F; Castellanos, Marcelo

    2008-01-01T23:59:59.000Z

    Circumnuclear star forming regions, also called hotspots, are often found in the inner regions of some spiral galaxies where intense processes of star formation are taking place. In the UV, massive stars dominate the observed circumnuclear emission even in the presence of an active nucleus, contributing between 30 and 50% to the H$\\beta$ total emission of the nuclear zone. Spectrophotometric data of moderate resolution (3000 < R < 11000) are presented from which the physical properties of the ionized gas: electron density, oxygen abundances, ionization structure etc. have been derived.

  8. Circumnuclear Regions of Star Formation in Early Type Galaxies

    E-Print Network [OSTI]

    Angeles I. Diaz; Elena Terlevich; Guillermo F. Hagele; Marcelo Castellanos

    2008-01-20T23:59:59.000Z

    Circumnuclear star forming regions, also called hotspots, are often found in the inner regions of some spiral galaxies where intense processes of star formation are taking place. In the UV, massive stars dominate the observed circumnuclear emission even in the presence of an active nucleus, contributing between 30 and 50% to the H$\\beta$ total emission of the nuclear zone. Spectrophotometric data of moderate resolution (3000 < R < 11000) are presented from which the physical properties of the ionized gas: electron density, oxygen abundances, ionization structure etc. have been derived.

  9. Properties of Post-AGB stars

    E-Print Network [OSTI]

    P. Garcia-Lario

    2006-05-18T23:59:59.000Z

    A review is presented of the most relevant results obtained in the last few years on this rare class of astronomical sources. Multi-wavelength analysis of an increasing number of post-AGB stars reveal that they constitute a more inhomogeneous population of stars than previously thought. The new data available allow us to study these sources with unprecedent spatial resolution and to extend our spectroscopic knowledge in a systematic way to the infrared for the first time, where crucial information is contained on the chemical composition of the gas and dust in their circumstellar shells. The overall infrared properties derived from ISO and Spitzer data can be used to trace the mass loss history and the chemical evolution of the ejected material. The new results impose severe observational constraints to the current nucleosynthesis models and suggest that the evolution is mainly determined not only by the initial mass but also by the metallicity of the progenitor star. Post-AGB samples are likely to grow in the near future with the advent of new data from space facilities like Spitzer or Akari. Studies of post-AGB stars in the galactic halo, the Magellanic Clouds and other galaxies of the Local Group will certainly improve our knowledge on the evolutionary connections between AGB stars and PNe.

  10. Varieties of Cotton for North Texas.

    E-Print Network [OSTI]

    Dunkle, P. B. (Paul Burtch)

    1930-01-01T23:59:59.000Z

    .............. Lone Star ........... Rowden Ladd Acre yield. pounds in 1 c%Z?n Variety Rowden ................ Lone Star .............. Matchless E . E . Big Boll . Per cent lint .... M'annamaker I3ank Account . . ICleveland... ............................ ............... Cleveland's Rig Roll ................. Kasch's Improved ........................ Lone Star ............ Ferguson's Round Nose .................. Broadwell's 11 . J ...................... Early King .................. Mexican jig ~oll...

  11. The Biological and Molecular Analysis of a Tick-Encoded Serine Protease Inhibitor (S6) and its Role in the Feeding Cycle of the Lone Star Tick, Amblyomma americanum (L) (Acari: ixodidae) 

    E-Print Network [OSTI]

    Chalaire, Katelyn Cox

    2011-10-21T23:59:59.000Z

    Serine protease inhibitors (serpins) are a large superfamily of proteins that regulate critical proteolytic pathways by inhibiting serine proteases. Tick-encoded serpins are thought to play a vital role in the feeding ...

  12. Linking the Metallicity Distribution of Galactic Halo Stars to the Enrichment History of the Universe

    E-Print Network [OSTI]

    Evan Scannapieco; Tom Broadhurst

    2001-02-06T23:59:59.000Z

    We compare the metallicity distribution of Galactic Halo stars with 3D realizations of hierarchical galaxy formation. Outflows from dwarf galaxies enrich the intergalactic medium inhomogeneously, at a rate depending on the local galaxy density. Consequently, the first stars created in small early-forming galaxies are less metal-rich that the first stars formed in more massive galaxies which typically form later. As most halo stars are likely to originate in accreted dwarfs, while disk stars formed out of outflow-enriched gas, this scenario naturally generates a ``metallicity floor'' for old disk stars, which we find to be roughly coincident with the higher end of our predicted metallicity distribution of halo stars, in agreement with observations. The broad and centrally peaked distribution of halo star metallicities is well reproduced in our models, with a natural dispersion depending on the exact accretion history. Our modeling includes the important ``baryonic stripping'' effect of early outflows, which brush away the tenuously held gas in neighboring pre-virialized density perturbations. This stripping process does not significantly modify the predicted shape of the halo star metal distribution but inhibits star-formation and hence the number of accreted stars, helping to reproduce the observed total Galactic halo luminosity and also the lack of low-luminosity local dwarf galaxies relative to N-body predictions.

  13. Relics of metal-free low mass stars exploding as thermonuclear supernovae

    E-Print Network [OSTI]

    Takuji Tsujimoto; Toshikazu Shigeyama

    2006-01-16T23:59:59.000Z

    Renewed interest in the first stars that were formed in the universe has led to the discovery of extremely iron-poor stars. Since several competing scenarios exist, our understanding of the mass range that determines the observed elemental abundances remains unclear. In this study, we consider three well-studied metal-poor stars in terms of the theoretical supernovae (SNe) model. Our results suggest that the observed abundance patterns in the metal-poor star BD +80 245 and the pair of stars HD 134439/40 agree strongly with the theoretical possibility that these stars inherited their heavy element abundance patterns from SNe initiated by thermonuclear runaways in the degenerate carbon-oxygen cores of primordial asymptotic giant branch stars with \\~3.5-5 solar masses. Recent theoretical calculations have predicted that such SNe could be originated from metal-free stars in the intermediate mass range. On the other hand, intermediate mass stars containing some metals would end their lives as white dwarfs after expelling their envelopes in the wind due to intense momentum transport from outgoing photons to heavy elements. This new pathway for the formation of SNe requires that stars are formed from the primordial gas. Thus, we suggest that stars of a few solar masses were formed from the primordial gas and that some of them caused thermonuclear explosions when the mass of their degenerate carbon-oxygen cores increased to the Chandrasekhar limit without experiencing efficient mass loss.

  14. Star Formation History of Omega Centauri Imprinted in Elemental Abundance Patterns

    E-Print Network [OSTI]

    Takuji Tsujimoto; Toshikazu Shigeyama

    2003-02-15T23:59:59.000Z

    The star formation history of the globular cluster Omega Centauri is investigated in the context of an inhomogeneous chemical evolution model in which supernovae induce star formation. The proposed model explains recent observations for Omega Cen stars, and divides star formation into three epochs. At the end of the first epoch, ~ 70% of the gas was expelled by supernovae. AGB stars then supplied s-process elements to the remaining gas during the first interval of ~300 Myr. This explains the observed sudden increase in Ba/Fe ratios in Omega Cen stars at [Fe/H] ~ -1.6. Supernovae at the end of the second epoch were unable to expel the gas. Eventually, Type Ia supernovae initiated supernova-induced star formation, and remaining gas was stripped when the cluster passed through the newly formed disk of the Milky Way. The formation of Omega Cen is also discussed in the framework of globular cluster formation triggered by cloud-cloud collisions. In this scenario, the relative velocity of clouds in the collision determines the later chemical evolution in the clusters. A head-on collision of proto-cluster clouds with a low relative velocity would have converted less than 1% of gas into stars and promoted the subsequent chemical evolution by supernova-driven star formation. This is consistent with present observed form of Omega Cen. In contrast, the other Galactic globular clusters are expected to have formed from more intense head-on collisions, and the resultant clouds would have been too thin for supernovae to accumulate enough gas to form the next generation of stars. This explains the absence of chemical evolution in these other globular clusters.

  15. One hundred first stars: Protostellar evolution and the final masses

    SciTech Connect (OSTI)

    Hirano, Shingo; Umeda, Hideyuki [Department of Astronomy, School of Science, University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan); Hosokawa, Takashi [Department of Physics and Research Center for the Early Universe, University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan); Yoshida, Naoki; Chiaki, Gen [Department of Physics, School of Science, University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan); Omukai, Kazuyuki [Astronomical Institute, Tohoku University, Sendai, Miyagi 980-8578 (Japan); Yorke, Harold W., E-mail: hirano@astron.s.u-tokyo.ac.jp [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2014-02-01T23:59:59.000Z

    We perform a large set of radiation hydrodynamic simulations of primordial star formation in a fully cosmological context. Our statistical sample of 100 First Stars shows that the first generation of stars has a wide mass distribution M {sub popIII} = 10 ? 1000 M {sub ?}. We first run cosmological simulations to generate a set of primordial star-forming gas clouds. We then follow protostar formation in each gas cloud and the subsequent protostellar evolution until the gas mass accretion onto the protostar is halted by stellar radiative feedback. The accretion rates differ significantly among the primordial gas clouds that largely determine the final stellar masses. For low accretion rates, the growth of a protostar is self-regulated by radiative feedback effects, and the final mass is limited to several tens of solar masses. At high accretion rates the protostar's outer envelope continues to expand, and the effective surface temperature remains low; such protostars do not exert strong radiative feedback and can grow in excess of 100 solar masses. The obtained wide mass range suggests that the first stars play a variety of roles in the early universe, by triggering both core-collapse supernovae and pair-instability supernovae as well as by leaving stellar mass black holes. We find certain correlations between the final stellar mass and the physical properties of the star-forming cloud. These correlations can be used to estimate the mass of the first star from the properties of the parent cloud or of the host halo without following the detailed protostellar evolution.

  16. Gas Shepherding by an Infalling Satellite

    E-Print Network [OSTI]

    P. Chang

    2008-05-22T23:59:59.000Z

    I calculate the action of a satellite, infalling through dynamical friction, on a coplanar gaseous disk of finite radial extent. The disk tides, raised by the infalling satellite, couple the satellite and disk. Dynamical friction acting on the satellite then shrinks the radius of the coupled satellite-disk system. Thus, the gas is ``shepherded'' to smaller radii. In addition, gas shepherding produces a large surface density enhancement at the disk edge. If the disk edge then becomes gravitationally unstable and fragments, it may give rise to enhanced star formation. On the other hand, if the satellite is sufficiently massive and dense, the gas may be transported from $\\sim 100$ pc to inside of a 10 to 10s of parsecs before completely fragmenting into stars. I argue that gas shepherding may drive the fueling of active galaxies and central starbursts and I compare this scenario to competing scenarios. I argue that sufficiently large and dense super star clusters (acting as the shepherding satellites) can shepherd a gas disk down to ten to tens of parsecs. Inside of ten to tens of parsecs, another mechanism may operate, i.e., cloud-cloud collisions or a marginally (gravitationally) stable disk, that drives the gas $\\lesssim 1$ pc, where it can be viscously accreted, feeding a central engine.

  17. Neutrostriction in Neutron stars

    E-Print Network [OSTI]

    V. K. Ignatovich

    2006-06-29T23:59:59.000Z

    It is demonstrated that not only gravity, but also neutrostriction forces due to optical potential created by coherent elastic neutron-neutron scattering can hold a neutron star together. The latter forces can be stronger than gravitational ones. The effect of these forces on mass, radius and structure of the neutron star is estimated.

  18. ISM dust feedback from low to high mass stars

    E-Print Network [OSTI]

    Falceta-Goncalves; D.

    2007-10-26T23:59:59.000Z

    The dust component of the interstellar medium (ISM) has been extensively studied in the past decades. Late-type stars have been assumed as the main source of dust to the ISM, but recent observations show that supernova remnants may play a role on the ISM dust feedback. In this work, I study the importance of low and high mass stars, as well as their evolutionary phase, on the ISM dust feedback process. I also determine the changes on the obtained results considering different mass distribution functions and star formation history. We describe a semi-empirical calculation of the relative importance of each star at each evolutionary phase in the dust ejection to the ISM. I compare the obtained results for two stellar mass distribution functions, the classic Salpeter initial mass function and the present day mass function. I used the evolutionary track models for each stellar mass, and the empirical mass-loss rates and dust-to-gas ratio. The relative contribution of each stellar mass depends on the used distribution. Ejecta from massive stars represent the most important objects for the ISM dust replenishment using the Salpeter IMF. On the other hand, for the present day mass function low and intermediate mass stars are dominant. Late-type giant and supergiant stars dominate the ISM dust feedback in our actual Galaxy, but this may not the case of galaxies experiencing high star formation rates, or at high redshifts. In those cases, SNe are dominant in the dust feedback process.

  19. Electrically charged compact stars

    E-Print Network [OSTI]

    Subharthi Ray; Manuel Malheiro; Jose' P. S. Lemos; Vilson T. Zanchin

    2006-04-17T23:59:59.000Z

    We review here the classical argument used to justify the electrical neutrality of stars and show that if the pressure and density of the matter and gravitational field inside the star are large, then a charge and a strong electric field can be present. For a neutron star with high pressure (~ 10^{33} to 10^{35} dynes /cm^2) and strong gravitational field (~ 10^{14} cm/s^2), these conditions are satisfied. The hydrostatic equation which arises from general relativity, is modified considerably to meet the requirements of the inclusion of the charge. In order to see any appreciable effect on the phenomenology of the neutron stars, the charge and the electrical fields have to be huge (~ 10^{21} Volts/cm). These stars are not however stable from the viewpoint that each charged particle is unbound to the uncharged particles, and thus the system collapses one step further to a charged black hole

  20. Three-dimensional modeling of ionized gas. II. Spectral energy distributions of massive and very massive stars in stationary and time-dependent modeling of the ionization of metals in HII regions

    E-Print Network [OSTI]

    Weber, J A; Hoffmann, T L

    2015-01-01T23:59:59.000Z

    HII regions play a crucial role in the measurement of the chemical composition of the interstellar medium and provide fundamental data about element abundances that constrain models of galactic chemical evolution. Discrepancies that still exist between observed emission line strengths and those predicted by nebular models can be partly attributed to the spectral energy distributions (SEDs) of the sources of ionizing radiation used in the models as well as simplifying assumptions made in nebular modeling. The influence of stellar metallicity on nebular line strength ratios, via its effect on the SEDs, is of similar importance as variations in the nebular metallicity. We have computed a grid of model atmosphere SEDs for massive and very massive O-type stars covering a range of metallicities from significantly subsolar (0.1 Zsun) to supersolar (2 Zsun). The SEDs have been computed using a state-of-the-art model atmosphere code that takes into account the attenuation of the ionizing flux by the spectral lines of ...

  1. Gas Powered Air Conditioning Absorption vs. Engine-Drive

    E-Print Network [OSTI]

    Phillips, J. N.

    1996-01-01T23:59:59.000Z

    It used to be that the only alternative to costly electric air conditioning was the double-effect gas-fired absorption chiller/heaters. Beginning in the 1980's, they were the "star" equipment promoted by gas companies throughout the nation. Although...

  2. Covered Product Category: Commercial Gas Water Heaters

    Broader source: Energy.gov [DOE]

    FEMP provides acquisition guidance and Federal efficiency requirements across a variety of product categories, including commercial gas water heaters, which are covered by the ENERGY STAR® program. Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.

  3. Covered Product Category: Residential Gas Furnaces

    Broader source: Energy.gov [DOE]

    FEMP provides acquisition guidance across a variety of product categories, including residential gas furnaces, which are an ENERGY STAR®-qualified product category. Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.

  4. Accretion of dust grains as a possible origin of metal-poor stars with low alpha/Fe ratios

    E-Print Network [OSTI]

    Toshikazu Shigeyama; Takuji Tsujimoto

    2003-10-10T23:59:59.000Z

    The origin of low alpha/Fe ratios in some metal-poor stars, so called low-alpha stars, is discussed. It is found that most of low-alpha stars in the Galaxy are on the main-sequence. This strongly suggests that these stars suffered from external pollution. It is also found that the abundance ratios Zn/Fe of low-alpha stars both in the Galaxy and in dwarf spheroidal galaxies are lower than the average value of Galactic halo stars whereas damped Ly alpha absorbers have higher ratios. This implies that some low-alpha stars accreted matter depleted from gas onto dust grains. To explain the features in these low-alpha stars, we have proposed that metal-poor stars harboring planetary systems are the origin of these low-alpha stars. Stars engulfing a small fraction of planetesimals enhance the surface content of Fe to exhibit low alpha/Fe ratios on their surfaces while they are on the main-sequence, because dwarfs have shallow surface convection zones where the engulfed matter is mixed. After the stars leave the main-sequence, the surface convection zones become deeper to reduce the enhancement of Fe. Eventually, when the stars ascend to the tip of the red giant branch, they engulf giant planets to become low-alpha stars again as observed in dwarf spheroidal galaxies. We predict that low-alpha stars with low Mn/Fe ratios harbor planetary systems.

  5. Helium enhancements in globular cluster stars from Asymptotic Giant Branch star pollution

    E-Print Network [OSTI]

    Amanda Karakas; Yeshe Fenner; Alison Sills; Simon Campbell; John Lattanzio

    2006-05-21T23:59:59.000Z

    Using a chemical evolution model we investigate the intriguing suggestion that there are populations of stars in some globular clusters (e.g. NGC 2808, omega Centauri) with enhanced levels of helium (Y from about 0.28 to 0.40) compared to the majority of the population that presumably have a primordial helium abundance. We assume that a previous generation of massive low-metallicity Asymptotic Giant Branch (AGB) stars has polluted the cluster gas via a slow stellar wind. We use two independent sets of AGB yields computed from detailed models to follow the evolution of helium, carbon, nitrogen and oxygen in the cluster gas using a Salpeter initial mass function (IMF) and a number of top-heavy IMFs. In no case were we able to fit the observational constraints, Y > 0.30 and C+N+O approximately constant. Depending on the shape of the IMF and the yields, we either obtained Y approximately greater than 0.30 and large increases in C+N+O or Y < 0.30 and C+N+O approximately constant. These results suggest that either AGB stars alone are not responsible for the large helium enrichment or that any dredge-up from this generation of stars was less than predicted by standard models.

  6. NIHAO III: The constant disc gas mass conspiracy

    E-Print Network [OSTI]

    Stinson, G S; Wang, L; Macciò, A V; Herpich, J; Bradford, J D; Quinn, T R; Wadsley, J; Keller, B

    2015-01-01T23:59:59.000Z

    We show that the cool gas masses of galactic discs reach a steady state that lasts many Gyr after their last major merger in cosmological hydrodynamic simulations. The mass of disc gas, M$_{\\rm gas}$, depends upon a galaxy halo's spin and virial mass, but not upon stellar feedback. Halos with low spin have high star formation efficiency and lower disc gas mass. Similarly, lower stellar feedback leads to more star formation so the gas mass ends up nearly the same irregardless of stellar feedback strength. Even considering spin, the M$_{\\rm gas}$ relation with halo mass, M$_{200}$ only shows a factor of 3 scatter. The M$_{\\rm gas}$--M$_{200}$ relation show a break at M$_{200}$=$2\\times10^{11}$ M$_\\odot$ that corresponds to an observed break in the M$_{\\rm gas}$--M$_\\star$ relation. The constant disc mass stems from a shared halo gas density profile in all the simulated galaxies. In their outer regions, the profiles are isothermal. Where the profile rises above $n=10^{-3}$ cm$^{-3}$, the gas readily cools and th...

  7. Planets of young stars

    E-Print Network [OSTI]

    E. W. Guenther; E. Esposito

    2007-01-10T23:59:59.000Z

    Since the first massive planet in a short period orbit was discovered, the question arised how such an object could have formed. There are basically two formation scenarios: migration due to planet-disk or planet-planet interaction. Which of the two scenarios is more realistic can be found out by observing short-period planets of stars with an age between 10E7 and 10E8 yrs. The second aim of the survey is to find out how many planets originally formed, and how many of these are destroyed in the first Gyrs: Do most young, close-in planets evaporate, or spiral into the host stars? In here we report on the first results of a radial-velocity search program for planets of young stars which we began in 2004. Using HARPS, we currently monitor 85 stars with ages between 10E7 and 10E8 yrs. We show that the detection of planets of young stars is possible. Up to now, we have identified 3 planet-candidates. Taking this result together with the results of other surveys, we conclude that the frequency of massive-short period planets of young stars is not dramatically higher than that of old stars.

  8. The Structure and Evolution of Stars Recommended Background Reading

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    . For material obeying the ideal gas equation P = (/µmH) kT, one can estimate the central temperature, Tc balance of gravity and internal pressure forces (hydrostatic equilibrium); · stars lose energy, e.g. nuclear energy, gravitational energy (energy equation); · the temperature structure is largely

  9. Characteristic structure of star-forming clouds

    E-Print Network [OSTI]

    Myers, Philip C

    2015-01-01T23:59:59.000Z

    This paper gives a new way to diagnose the star-forming potential of a molecular cloud region from the probability density function of its column density (N-pdf). It gives expressions for the column density and mass profiles of a symmetric filament having the same N-pdf as a filamentary region. The central concentration of this characteristic filament can distinguish regions and can quantify their fertility for star formation. Profiles are calculated for N-pdfs which are pure lognormal, pure power law, or a combination. In relation to models of singular polytropic cylinders, characteristic filaments can be unbound, bound, or collapsing depending on their central concentration. Such filamentary models of the dynamical state of N-pdf gas are more relevant to star-forming regions than are models of spherical collapse. The star formation fertility of a bound or collapsing filament is quantified by its mean mass accretion rate when in radial free fall. For a given mass per length, the fertility increases with the ...

  10. Hypernuclear Physics for Neutron Stars

    E-Print Network [OSTI]

    Jurgen Schaffner-Bielich

    2008-01-24T23:59:59.000Z

    The role of hypernuclear physics for the physics of neutron stars is delineated. Hypernuclear potentials in dense matter control the hyperon composition of dense neutron star matter. The three-body interactions of nucleons and hyperons determine the stiffness of the neutron star equation of state and thereby the maximum neutron star mass. Two-body hyperon-nucleon and hyperon-hyperon interactions give rise to hyperon pairing which exponentially suppresses cooling of neutron stars via the direct hyperon URCA processes. Non-mesonic weak reactions with hyperons in dense neutron star matter govern the gravitational wave emissions due to the r-mode instability of rotating neutron stars.

  11. High energy gamma rays from old accreting neutron stars

    E-Print Network [OSTI]

    P. Blasi

    1996-06-28T23:59:59.000Z

    We consider a magnetized neutron star with accretion from a companion star or a gas cloud around it, as a possible source of gamma rays with energy between $100$ $MeV$ and $10^{14}-10^{16}~eV$. The flow of the accreting plasma is terminated by a shock at the Alfv\\'en surface. Such a shock is the site for the acceleration of particles up to energies of $\\sim 10^{15}-10^{17}~eV$; gamma photons are produced in the inelastic $pp$ collisions between shock-accelerated particles and accreting matter. The model is applied to old neutron stars both isolated or in binary systems. The gamma ray flux above $100~MeV$ is not easily detectable, but we propose that gamma rays with very high energy could be used by Cherenkov experiments as a possible signature of isolated old neutron stars in dense clouds in our galaxy.

  12. Monolithic or hierarchical star formation? A new statistical analysis

    E-Print Network [OSTI]

    Marios Kampakoglou; Roberto Trotta; Joe Silk

    2007-11-23T23:59:59.000Z

    We consider an analytic model of cosmic star formation which incorporates supernova feedback, gas accretion and enriched outflows, reproducing the history of cosmic star formation, metallicity, supernovae type II rates and the fraction of baryons allocated to structures. We present a new statistical treatment of the available observational data on the star formation rate and metallicity that accounts for the presence of possible systematics. We then employ a Bayesian Markov Chain Monte Carlo method to compare the predictions of our model with observations and derive constraints on the 7 free parameters of the model. We find that the dust correction scheme one chooses to adopt for the star formation data is critical in determining which scenario is favoured between a hierarchical star formation model, where star formation is prolonged by accretion, infall and merging, and a monolithic scenario, where star formation is rapid and efficient. We distinguish between these modes by defining a characteristic minimum mass, M > 10^{11} M_solar, in our fiducial model, for early type galaxies where star formation occurs efficiently. Our results indicate that the hierarchical star formation model can achieve better agreement with the data, but that this requires a high efficiency of supernova-driven outflows. In a monolithic model, our analysis points to the need for a mechanism that drives metal-poor winds, perhaps in the form of supermassive black hole-induced outflows. Furthermore, the relative absence of star formation beyond z ~ 5 in the monolithic scenario requires an alternative mechanism to dwarf galaxies for reionizing the universe at z ~ 11, as required by observations of the microwave background. While the monolithic scenario is less favoured in terms of its quality-of-fit, it cannot yet be excluded.

  13. Strangeness in Neutron Stars

    E-Print Network [OSTI]

    Fridolin Weber; Alexander Ho; Rodrigo P. Negreiros; Philip Rosenfield

    2006-04-20T23:59:59.000Z

    It is generally agreed on that the tremendous densities reached in the centers of neutron stars provide a high-pressure environment in which several intriguing particles processes may compete with each other. These range from the generation of hyperons to quark deconfinement to the formation of kaon condensates and H-matter. There are theoretical suggestions of even more exotic processes inside neutron stars, such as the formation of absolutely stable strange quark matter. In the latter event, neutron stars would be largely composed of strange quark matter possibly enveloped in a thin nuclear crust. This paper gives a brief overview of these striking physical possibilities with an emphasis on the role played by strangeness in neutron star matter, which constitutes compressed baryonic matter at ultra-high baryon number density but low temperature which is no accessible to relativistic heavy ion collision experiments.

  14. Masers and star formation

    E-Print Network [OSTI]

    Vincent L. Fish

    2007-04-02T23:59:59.000Z

    Recent observational and theoretical advances concerning astronomical masers in star forming regions are reviewed. Major masing species are considered individually and in combination. Key results are summarized with emphasis on present science and future prospects.

  15. COALESCING NEUTRON STARS AS GAMMA RAY BURSTERS ?

    E-Print Network [OSTI]

    M. Ruffert; H. -Th. Janka; W. Keil; G. Schaefer

    1995-03-06T23:59:59.000Z

    We investigate the dynamics and evolution of coalescing neutron stars. The three-dimensional Newtonian equations of hydrodynamics are integrated by the `Piecewise Parabolic Method' However, we do include the effects of the emission of gravitational waves on the hydrodynamics. The properties of neutron star matter are described by the equation of state of Lattimer & Swesty. In addition to the fundamental hydrodynamic quantities, density, momentum, and energy, we follow the time evolution of the electron density in the stellar gas. Energy losses and changes of the electron abundance due to the emission of neutrinos are taken into account by an elaborate ``neutrino leakage scheme'', which employs a careful calculation of the lepton number and energy source terms of all neutrino types. The grid is Cartesian and equidistant with a resolution of 64**3 or 128**3, which allows us to calculate the self-gravity via fast Fourier transforms.

  16. Towards a metallurgy of neutron star crusts

    E-Print Network [OSTI]

    Kobyakov, D

    2013-01-01T23:59:59.000Z

    In the standard picture of the crust of a neutron star, matter there is simple: a body-centered-cubic (bcc) lattice of nuclei immersed in an essentially uniform electron gas. We show that at densities above that for neutron drip ($\\sim4\\times10^11$) g cm$^{-3}$ or roughly one thousandth of nuclear matter density, the interstitial neutrons give rise to an attractive interaction between nuclei that renders the lattice unstable. We argue that the likely equilibrium structure is similar to that in displacive ferroelectric materials such as BaTiO$_3$. As a consequence, properties of matter in the inner crust are expected to be much richer than previously appreciated and we mention consequences for observable neutron star properties.

  17. Towards a metallurgy of neutron star crusts

    E-Print Network [OSTI]

    D. Kobyakov; C. J. Pethick

    2013-09-07T23:59:59.000Z

    In the standard picture of the crust of a neutron star, matter there is simple: a body-centered-cubic (bcc) lattice of nuclei immersed in an essentially uniform electron gas. We show that at densities above that for neutron drip ($\\sim4\\times10^11$) g cm$^{-3}$ or roughly one thousandth of nuclear matter density, the interstitial neutrons give rise to an attractive interaction between nuclei that renders the lattice unstable. We argue that the likely equilibrium structure is similar to that in displacive ferroelectric materials such as BaTiO$_3$. As a consequence, properties of matter in the inner crust are expected to be much richer than previously appreciated and we mention consequences for observable neutron star properties.

  18. Gas Feedback on Stellar Bar Evolution

    E-Print Network [OSTI]

    Ingo Berentzen; Isaac Shlosman; Inma Martinez-Valpuesta; Clayton Heller

    2007-05-27T23:59:59.000Z

    We analyze evolution of live disk-halo systems in the presence of various gas fractions, f_gas less than 8% in the disk. We addressed the issue of angular momentum (J) transfer from the gas to the bar and its effect on the bar evolution. We find that the weakening of the bar, reported in the literature, is not related to the J-exchange with the gas, but is caused by the vertical buckling instability in the gas-poor disks and by a steep heating of a stellar velocity dispersion by the central mass concentration (CMC) in the gas-rich disks. The gas has a profound effect on the onset of the buckling -- larger f_gas brings it forth due to the more massive CMCs. The former process leads to the well-known formation of the peanut-shaped bulges, while the latter results in the formation of progressively more elliptical bulges, for larger f_gas. The subsequent (secular) evolution of the bar differs -- the gas-poor models exhibit a growing bar while gas-rich models show a declining bar whose vertical swelling is driven by a secular resonance heating. The border line between the gas-poor and -rich models lies at f_gas ~ 3% in our models, but is model-dependent and will be affected by additional processes, like star formation and feedback from stellar evolution. The overall effect of the gas on the evolution of the bar is not in a direct J transfer to the stars, but in the loss of J by the gas and its influx to the center that increases the CMC. The more massive CMC damps the vertical buckling instability and depopulates orbits responsible for the appearance of peanut-shaped bulges. The action of resonant and non-resonant processes in gas-poor and gas-rich disks leads to a converging evolution in the vertical extent of the bar and its stellar dispersion velocities, and to a diverging evolution in the bulge properties.

  19. Lower Metal Enrichment of Virialized Gas in Minihalos

    E-Print Network [OSTI]

    Renyue Cen; Mario A. Riquelme

    2007-04-26T23:59:59.000Z

    We differentiate between the metal enrichment of the gas in virialized minihalos and that of the intergalactic medium at high redshift, pertinent to cosmological reionization, with the initial expectation that gas in the high density regions within formed dark matter halos may be more robust thus resistant to mixing with lower density intergalactic medium. Using detailed hydrodynamic simulations of gas clouds in minihalos subject to destructive processes associated with the encompassing intergalactic shocks carrying metal-enriched gas, we find, as an example, that, for realistic shocks of velocities of 10-100km/s, more than (90%,65%) of the high density gas with rho>500 rhob inside a minihalo virialized at z=10 of mass (10^7,10^6)Msun remains at a metallicity lower than 3% of that of the intergalactic medium by redshift z=6. It may be expected that the high density gas in minihalos becomes fuel for subsequent star formation, when they are incorporated into larger halos where efficient atomic cooling can induce gas condensation hence star formation. Since minihalos virialize at high redshift when the universe is not expected to have been significantly reionized, the implication is that gas in virialized minihalos may provide an abundant reservoir of primordial gas to possibly allow for the formation of Population-III metal-free stars to extend to much lower redshift than otherwise expected based on the enrichment of intergalactic medium.

  20. Extent of pollution in planet-bearing stars

    E-Print Network [OSTI]

    S. -L. Li; D. N. C. Lin; X. -W. Liu

    2008-02-17T23:59:59.000Z

    (abridged) Search for planets around main-sequence (MS) stars more massive than the Sun is hindered by their hot and rapidly spinning atmospheres. This obstacle has been sidestepped by radial-velocity surveys of those stars on their post-MS evolutionary track (G sub-giant and giant stars). Preliminary observational findings suggest a deficiency of short-period hot Jupiters around the observed post MS stars, although the total fraction of them with known planets appears to increase with their mass. Here we consider the possibility that some very close- in gas giants or a population of rocky planets may have either undergone orbital decay or been engulfed by the expanding envelope of their intermediate-mass host stars. If such events occur during or shortly after those stars' main sequence evolution when their convection zone remains relatively shallow, their surface metallicity can be significantly enhanced by the consumption of one or more gas giants. We show that stars with enriched veneer and lower-metallicity interior follow slightly modified evolution tracks as those with the same high surface and interior metallicity. As an example, we consider HD149026, a marginal post MS 1.3 Msun star. We suggest that its observed high (nearly twice solar) metallicity may be confined to the surface layer as a consequence of pollution by the accretion of either a planet similar to its known 2.7-day-period Saturn-mass planet, which has a 70 Mearth compact core, or a population of smaller mass planets with a comparable total amount of heavy elements. It is shown that an enhancement in surface metallicity leads to a reduction in effective temperature, in increase in radius and a net decrease in luminosity. The effects of such an enhancement are not negligible in the determinations of the planet's radius based on the transit light curves.

  1. Star Formation in Isolated Disk Galaxies. II. Schmidt Laws and Efficiency of Gravitational Collapse

    E-Print Network [OSTI]

    Yuexing Li; Mordecai-Mark Mac Low; Ralf S. Klessen

    2006-02-21T23:59:59.000Z

    (Abridged). We model gravitational instability in a wide range of isolated disk galaxies, using GADGET, a three-dimensional, smoothed particle hydrodynamics code. The model galaxies include a dark matter halo and a disk of stars and isothermal gas. The global Schmidt law observed in disk galaxies is quantitatively reproduced by our models. We find that the surface density of star formation rate directly correlates with the strength of local gravitational instability. The local Schmidt laws of individual galaxies in our models show clear evidence of star formation thresholds. Our results suggest that the non-linear development of gravitational instability determines the local and global Schmidt laws, and the star formation thresholds.

  2. STAR Facility Tritium Accountancy

    SciTech Connect (OSTI)

    R. J. Pawelko; J. P. Sharpe; B. J. Denny

    2007-09-01T23:59:59.000Z

    The Safety and Tritium Applied Research (STAR) facility has been established to provide a laboratory infrastructure for the fusion community to study tritium science associated with the development of safe fusion energy and other technologies. STAR is a radiological facility with an administrative total tritium inventory limit of 1.5g (14,429 Ci) [1]. Research studies with moderate tritium quantities and various radionuclides are performed in STAR. Successful operation of the STAR facility requires the ability to receive, inventory, store, dispense tritium to experiments, and to dispose of tritiated waste while accurately monitoring the tritium inventory in the facility. This paper describes tritium accountancy in the STAR facility. A primary accountancy instrument is the tritium Storage and Assay System (SAS): a system designed to receive, assay, store, and dispense tritium to experiments. Presented are the methods used to calibrate and operate the SAS. Accountancy processes utilizing the Tritium Cleanup System (TCS), and the Stack Tritium Monitoring System (STMS) are also discussed. Also presented are the equations used to quantify the amount of tritium being received into the facility, transferred to experiments, and removed from the facility. Finally, the STAR tritium accountability database is discussed.

  3. STAR facility tritium accountancy

    SciTech Connect (OSTI)

    Pawelko, R. J.; Sharpe, J. P.; Denny, B. J. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 (United States)

    2008-07-15T23:59:59.000Z

    The Safety and Tritium Applied Research (STAR) facility has been established to provide a laboratory infrastructure for the fusion community to study tritium science associated with the development of safe fusion energy and other technologies. STAR is a radiological facility with an administrative total tritium inventory limit of 1.5 g (14,429 Ci) [1]. Research studies with moderate tritium quantities and various radionuclides are performed in STAR. Successful operation of the STAR facility requires the ability to receive, inventory, store, dispense tritium to experiments, and to dispose of tritiated waste while accurately monitoring the tritium inventory in the facility. This paper describes tritium accountancy in the STAR facility. A primary accountancy instrument is the tritium Storage and Assay System (SAS): a system designed to receive, assay, store, and dispense tritium to experiments. Presented are the methods used to calibrate and operate the SAS. Accountancy processes utilizing the Tritium Cleanup System (TCS), and the Stack Tritium Monitoring System (STMS) are also discussed. Also presented are the equations used to quantify the amount of tritium being received into the facility, transferred to experiments, and removed from the facility. Finally, the STAR tritium accountability database is discussed. (authors)

  4. Triggered star formation on the borders of the Galactic HII region RCW 82

    E-Print Network [OSTI]

    M. Pomares; A. Zavagno; L. Deharveng; M. Cunningham; P. Jones; S. Kurtz; D. Russeil; J. Caplan; F. Comeron

    2008-12-14T23:59:59.000Z

    We are engaged in a multi-wavelength study of several Galactic HII regions that exhibit signposts of triggered star formation on their borders, and where the collect and collapse process could be at work. When addressing the question of triggered star formation it is critically important to ensure the real association between the ionized gas and the neutral material observed nearby. In this paper we stress this point, and present CO observations of the RCW 82 star forming region. The velocity distribution of the molecular gas is combined with the study of young stellar objects (YSOs) detected in the direction of RCW 82. We discuss the YSO's evolutionary status using near- and mid-IR data. The spatial and velocity distributions of the molecular gas are used to discuss the possible scenarios for the star formation around RCW 82.

  5. THE CHEMICAL IMPRINT OF SILICATE DUST ON THE MOST METAL-POOR STARS

    E-Print Network [OSTI]

    Bromm, Volker

    We investigate the impact of dust-induced gas fragmentation on the formation of the first low-mass, metal-poor stars (<1 M[subscript ?]) in the early universe. Previous work has shown the existence of a critical dust-to-gas ...

  6. Turbulent Compressibilty of Protogalactic Gas

    E-Print Network [OSTI]

    John Scalo; Anirban Biswas

    2001-11-09T23:59:59.000Z

    The star formation rate in galaxies should be related to the fraction of gas that can attain densities large enough for gravitational collapse. In galaxies with a turbulent interstellar medium, this fraction is controlled by the effective barotropic index $gamma = dlog P/dlog (rho)$ which measures the turbulent compressibility. When the cooling timescale is smaller than the dynamical timescale, gamma can be evaluated from the derivatives of cooling and heating functions, using the condition of thermal equilibrium. We present calculations of gamma for protogalaxies in which the metal abundance is so small that H_2 and HD cooling dominates. For a heating rate independent of temperature and proportional to the first power of density, the turbulent gas is relatively "hard", with $gamma >= 1$, at large densities, but moderately "soft", $gamma <= 0.8$, at densities below around $10^4 cm^(-3)$. At low temperatures the density probability distribution should fall ra pidly for densities larger than this value, which corresponds physically to the critical density at which collisional and radiative deexcitation rate s of HD are equal. The densities attained in turbulent protogalaxies thus depend on the relatively large deuterium abundance in our universe. We expect the same physical effect to occur in higher metallicity gas with different coolants. The case in which adiabatic (compressional) heating due to cloud collapse dominates is also discussed, and suggests a criterion for the maximum mass of Population III stars.

  7. The Abundance Distribution in the Extrasolar-Planet Host Star HD19994

    E-Print Network [OSTI]

    Verne V. Smith; Katia Cunha; Daniela Lazzaro

    2001-03-04T23:59:59.000Z

    Abundances of 22 elements have been determined from a high-resolution, high signal-to-noise spectrum of HD19994, a star recently announced as harboring an extrasolar planet. A detailed spectroscopic analysis of this stars finds it to have a mass of 1.2+/-0.1Msun. HD19994 is found to be slightly enriched in "metals" relative to the Sun 9[Fe/H]=+0.09+/-0.05 and an average of all metals of [m/H]=+0.13), as are most stars known with extrasolar planets. In a search for possible signatures of accretion of metal-rich gas onto the parent stars (using HD19994 and published abundances for other stars), it is found that a small subset of stars with planets exhibit a trend of increasing [X/H] with increasing condensation temperature for a given element X. This trend may point to the accretion of chemically fractionated solid material into the outer (thin) convection zones of these solar-type stars. It is also found that this small group of stars exhibiting an accretion signature all have large planets orbiting much closer than is found, in general, for stars with planets not showing this peculiar abundance trend, suggesting a physical link between accretion and orbital separation. In addition, the stars showing evidence of fractionated accretion are, on average, of larger mass (1.2Msun) than stars not showing measurable evidence of accretion (1.0Msun).

  8. Stellar Populations in Circumnuclear Star Forming Regions

    E-Print Network [OSTI]

    A. I. Diaz; M. Alvarez-Alvarez; M. Castellanos

    2002-05-07T23:59:59.000Z

    We present a study of the stellar populations and gas physical conditions in Circumnuclear Star Forming Regions (CNSFR) based on broad and narrow band photometry and spectrophotometric data, which have been analyzed with the use of evolutionary population synthesis and photoionization models. It is found that most CNSFR show composite stellar populations of slightly different ages. They seem to have the highest abundances in HII region-like objects, showing also N/O overabundances and S/O underabundances by a factor of about three. Also, CNSFR as a class, segregate from the disk HII region family, clustering around smaller $\\eta$' values, and thereforefore higher ionizing temperatures.

  9. Strangeness in Neutron Stars

    E-Print Network [OSTI]

    Fridolin Weber

    2000-08-23T23:59:59.000Z

    It is generally agreed on that the tremendous densities reached in the centers of neutron stars provide a high-pressure environment in which numerous novel particles processes are likely to compete with each other. These processes range from the generation of hyperons to quark deconfinement to the formation of kaon condensates and H-matter. There are theoretical suggestions of even more exotic processes inside neutron stars, such as the formation of absolutely stable strange quark matter, a configuration of matter even more stable than the most stable atomic nucleus, iron. In the latter event, neutron stars would be largely composed of pure quark matter, eventually enveloped in a thin nuclear crust. No matter which physical processes are actually realized inside neutron stars, each one leads to fingerprints, some more pronounced than others though, in the observable stellar quantities. This feature combined with the unprecedented progress in observational astronomy, which allows us to see vistas with remarkable clarity that previously were only imagined, renders neutron stars to nearly ideal probes for a wide range of physical studies, including the role of strangeness in dense matter.

  10. Dark Stars: A Review

    E-Print Network [OSTI]

    Freese, Katherine; Spolyar, Douglas; Valluri, Monica

    2015-01-01T23:59:59.000Z

    Dark Stars (DS) are stellar objects made (almost entirely) of ordinary atomic material but powered by the heat from Dark Matter (DM) annihilation (rather than by fusion). Weakly Interacting Massive Particles (WIMPs), among the best candidates for DM, can be their own antimatter and can accumulate inside the star, with their annihilation products thermalizing with and heating the DS. The resulting DSs are in hydrostatic and thermal equilibrium. The first phase of stellar evolution in the history of the Universe may have been dark stars. Though DM constituted only $10^6 M_\\odot$), very bright ($>10^9 L_\\odot$), and potentially detectable with the James Webb Space Telescope (JWST). Once the DM runs out and the dark star dies, it may collapse to a black hole; thus DSs can provide seeds for the supermassive black holes observed throughout the Universe and at early times. Other sites for dark star formation exist in the Universe today in regions of high dark matter density such as the centers of galaxies. The curre...

  11. Two-Dimensional Hydrodynamic Models of Super Star Clusters with a Positive Star Formation Feedback

    E-Print Network [OSTI]

    Wünsch, R; Palous, J; Silich, S

    2008-01-01T23:59:59.000Z

    Using the hydrodynamic code ZEUS, we perform 2D simulations to determine the fate of the gas ejected by massive stars within super star clusters. It turns out that the outcome depends mainly on the mass and radius of the cluster. In the case of less massive clusters, a hot high velocity ($\\sim 1000$ km s$^{-1}$) stationary wind develops and the metals injected by supernovae are dispersed to large distances from the cluster. On the other hand, the density of the thermalized ejecta within massive and compact clusters is sufficiently large as to immediately provoke the onset of thermal instabilities. These deplete, particularly in the central densest regions, the pressure and the pressure gradient required to establish a stationary wind, and instead the thermally unstable parcels of gas are rapidly compressed, by a plethora of re-pressurizing shocks, into compact high density condensations. Most of these are unable to leave the cluster volume and thus accumulate to eventually feed further generations of star for...

  12. Pre-main sequence stars, emission stars and recent star formation in the Cygnus Region

    E-Print Network [OSTI]

    Bhavya B; Blesson Mathew; Annapurni Subramaniam

    2008-04-09T23:59:59.000Z

    The recent star formation history in the Cygnus region is studied using 5 clusters (IC 4996, NGC 6910, Berkeley 87, Biurakan 2 and Berkeley 86). The optical data from the literature are combined with the 2MASS data to identify the pre-main sequence (pre-MS) stars as stars with near IR excess. We identified 93 pre-MS stars and 9 stars with H$_\\alpha$ emission spectra. The identified pre-MS stars are used to estimate the turn-on age of the clusters. The duration of star formation was estimated as the difference between the turn-on and the turn-off age. We find that, NGC 6910 and IC 4996 have been forming stars continuously for the last 6 -- 7 Myr, Berkeley 86 and Biurakan 2 for 5 Myr and Berkeley 87 for the last 2 Myr. This indicates that the Cygnus region has been actively forming stars for the last 7 Myr, depending on the location. 9 emission line stars were identified in 4 clusters, using slit-less spectra (Be 87 - 4 stars; Be 86 - 2 stars, NGC 6910 - 2 stars and IC 4996 - 1 star). The individual spectra were obtained and analysed to estimate stellar as well as disk properties. All the emission stars are in the MS, well below the turn-off, in the core hydrogen burning phase. These stars are likely to be Classical Be (CBe) stars. Thus CBe phenomenon can be found in very young MS stars which are just a few (2 -- 7) Myrs old. This is an indication that CBe phenomenon need not be an evolutionary effect.

  13. Spectropolarimetry of cool stars

    E-Print Network [OSTI]

    P. Petit

    2007-03-27T23:59:59.000Z

    In recent years, the development of spectropolarimetric techniques deeply modified our knowledge of stellar magnetism. In the case of solar-type stars, the challenge is to measure a geometrically complex field and determine its evolution over very different time frames. In this article, I summarize some important observational results obtained in this field over the last two decades and detail what they tell us about the dynamo processes that orchestrate the activity of cool stars. I also discuss what we learn from such observations about the ability of magnetic fields to affect the formation and evolution of Sun-like stars. Finally, I evoke promising directions to be explored in the coming years, thanks to the advent of a new generation of instruments specifically designed to progress in this domain.

  14. Gas sensor

    DOE Patents [OSTI]

    Schmid, Andreas K.; Mascaraque, Arantzazu; Santos, Benito; de la Figuera, Juan

    2014-09-09T23:59:59.000Z

    A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas. In one embodiment the stack sensor comprises a top ferromagnetic layer two mono layers thick of cobalt deposited upon a spacer layer of ruthenium, which in turn has a second layer of cobalt disposed on its other side, this second cobalt layer in contact with a programmable heater chip.

  15. Isolating Triggered Star Formation

    SciTech Connect (OSTI)

    Barton, Elizabeth J.; Arnold, Jacob A.; /UC, Irvine; Zentner, Andrew R.; /KICP, Chicago /Chicago U., EFI; Bullock, James S.; /UC, Irvine; Wechsler, Risa H.; /KIPAC, Menlo

    2007-09-12T23:59:59.000Z

    Galaxy pairs provide a potentially powerful means of studying triggered star formation from galaxy interactions. We use a large cosmological N-body simulation coupled with a well-tested semi-analytic substructure model to demonstrate that the majority of galaxies in close pairs reside within cluster or group-size halos and therefore represent a biased population, poorly suited for direct comparison to 'field' galaxies. Thus, the frequent observation that some types of galaxies in pairs have redder colors than 'field' galaxies is primarily a selection effect. We use our simulations to devise a means to select galaxy pairs that are isolated in their dark matter halos with respect to other massive subhalos (N= 2 halos) and to select a control sample of isolated galaxies (N= 1 halos) for comparison. We then apply these selection criteria to a volume-limited subset of the 2dF Galaxy Redshift Survey with M{sub B,j} {le} -19 and obtain the first clean measure of the typical fraction of galaxies affected by triggered star formation and the average elevation in the star formation rate. We find that 24% (30.5 %) of these L* and sub-L* galaxies in isolated 50 (30) h{sup -1} kpc pairs exhibit star formation that is boosted by a factor of {approx}> 5 above their average past value, while only 10% of isolated galaxies in the control sample show this level of enhancement. Thus, 14% (20 %) of the galaxies in these close pairs show clear triggered star formation. Our orbit models suggest that 12% (16%) of 50 (30) h{sup -1} kpc close pairs that are isolated according to our definition have had a close ({le} 30 h{sup -1} kpc) pass within the last Gyr. Thus, the data are broadly consistent with a scenario in which most or all close passes of isolated pairs result in triggered star formation. The isolation criteria we develop provide a means to constrain star formation and feedback prescriptions in hydrodynamic simulations and a very general method of understanding the importance of triggered star formation in a cosmological context.

  16. Synthetic guide star generation

    DOE Patents [OSTI]

    Payne, Stephen A.; Page, Ralph H.; Ebbers, Christopher A.; Beach, Raymond J.

    2004-03-09T23:59:59.000Z

    A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

  17. Synthetic guide star generation

    DOE Patents [OSTI]

    Payne, Stephen A. (Castro Valley, CA) [Castro Valley, CA; Page, Ralph H. (Castro Valley, CA) [Castro Valley, CA; Ebbers, Christopher A. (Livermore, CA) [Livermore, CA; Beach, Raymond J. (Livermore, CA) [Livermore, CA

    2008-06-10T23:59:59.000Z

    A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

  18. A Star on Earth

    ScienceCinema (OSTI)

    Prager, Stewart; Zwicker, Andrew; Hammet, Greg; Tresemer, Kelsey; Diallo, Ahmed

    2014-06-06T23:59:59.000Z

    At the Energy Department's Princeton Plasma Physics Lab, scientists are trying to accomplish what was once considered the realm of science fiction: create a star on Earth. The National Spherical Torus Experiment (NSTX) is a magnetic fusion device that is used to study the physics principles of spherically shaped plasmas -- hot ionized gases in which, under the right conditions, nuclear fusion will occur. Fusion is the energy source of the sun and all of the stars. Not just limited to theoretical work, the NSTX is enabling cutting-edge research to develop fusion as a future energy source.

  19. A Star on Earth

    SciTech Connect (OSTI)

    Prager, Stewart; Zwicker, Andrew; Hammet, Greg; Tresemer, Kelsey; Diallo, Ahmed

    2014-03-05T23:59:59.000Z

    At the Energy Department's Princeton Plasma Physics Lab, scientists are trying to accomplish what was once considered the realm of science fiction: create a star on Earth. The National Spherical Torus Experiment (NSTX) is a magnetic fusion device that is used to study the physics principles of spherically shaped plasmas -- hot ionized gases in which, under the right conditions, nuclear fusion will occur. Fusion is the energy source of the sun and all of the stars. Not just limited to theoretical work, the NSTX is enabling cutting-edge research to develop fusion as a future energy source.

  20. CFL Manufacturers: ENERGY STAR Letters

    Broader source: Energy.gov [DOE]

    DOE issued letters to 25 manufacturers of compact fluorescent lamps (CFLs) involving various models after PEARL Cycle 9 testing indicated that the models do not meet the ENERGY STAR specification and, therefore, are disqualified from the ENERGY STAR Program.

  1. Lithium in LMC carbon stars

    E-Print Network [OSTI]

    D. Hatzidimitriou; D. H. Morgan; R. D. Cannon; B. F. W. Croke

    2003-04-16T23:59:59.000Z

    Nineteen carbon stars that show lithium enrichment in their atmospheres have been discovered among a sample of 674 carbon stars in the Large Magellanic Cloud. Six of the Li-rich carbon stars are of J-type, i.e. with strong 13C isotopic features. No super-Li-rich carbon stars were found. The incidence of lithium enrichment among carbon stars in the LMC is much rarer than in the Galaxy, and about five times more frequent among J-type than among N-type carbon stars. The bolometric magnitudes of the Li-rich carbon stars range between -3.3 and -5.7. Existing models of Li-enrichment via the hot bottom burning process fail to account for all of the observed properties of the Li-enriched stars studied here.

  2. Gas Density and the Volume Schmidt Law for Spiral Galaxies

    E-Print Network [OSTI]

    O. V. Abramova; A. V. Zasov

    2007-10-01T23:59:59.000Z

    The thickness of the equilibrium isothermal gaseous layers and their volume densities \\rho_{gas}(R) in the disc midplane are calculated for 7 spiral galaxies (including our Galaxy) in the frame of self-consistent axisymmetric model. Local velocity dispersions of stellar discs were assumed to be close to marginal values necessary for the discs to be in a stable equilibrium state. Under this condition the stellar discs of at least 5 of 7 galaxies reveal a flaring. Their volume densities decrease with R faster than \\rho_{gas}, and, as a result, the gas dominates by the density at the disc periphery. Comparison of the azimuthally averaged star formation rate SFR with the gas density shows that there is no universal Schmidt law SFR \\rho_{gas}^n, common to all galaxies. Nevertheless, SFR in different galaxies reveals better correlation with the volume gas density than with the column one. Parameter n in the Schmidt law SFR \\rho_{gas}^n, formally calculated by the least square method, lies within 0.8-2.4 range and it's mean value is close to 1.5. Values of n calculated for molecular gas only are characterized by large dispersion, but their mean value is close to 1. Hence the smaller \\rho_{gas} the less is a fraction of gas actively taking part in the process of star formation.

  3. NATURAL GAS MARKET ASSESSMENT

    E-Print Network [OSTI]

    CALIFORNIA ENERGY COMMISSION NATURAL GAS MARKET ASSESSMENT PRELIMINARY RESULTS In Support.................................................................................... 6 Chapter 2: Natural Gas Demand.................................................................................................. 10 Chapter 3: Natural Gas Supply

  4. Radiation Pressure in Massive Star Formation

    E-Print Network [OSTI]

    Mark R. Krumholz; Richard I. Klein; Christopher F. McKee

    2005-10-14T23:59:59.000Z

    Stars with masses of >~ 20 solar masses have short Kelvin times that enable them to reach the main sequence while still accreting from their natal clouds. The resulting nuclear burning produces a huge luminosity and a correspondingly large radiation pressure force on dust grains in the accreting gas. This effect may limit the upper mass of stars that can form by accretion. Indeed, simulations and analytic calculations to date have been unable to resolve the mystery of how stars of 50 solar masses and up form. We present two new ideas to solve the radiation pressure problem. First, we use three-dimensional radiation hydrodynamic adaptive mesh refinement simulations to study the collapse of massive cores. We find that in three dimensions a configuration in which radiation holds up an infalling envelope is Rayleigh-Taylor unstable, leading radiation driven bubbles to collapse and accretion to continue. We also present Monte Carlo radiative transfer calculations showing that the cavities created by protostellar winds provides a valve that allow radiation to escape the accreting envelope, further reducing the ability of radiation pressure to inhibit accretion.

  5. Dynamical Expansion of Ionization and Dissociation Front around a Massive Star. I. A Mode of Triggered Star Formation

    E-Print Network [OSTI]

    Takashi Hosokawa; Shu-ichiro Inutsuka

    2005-01-08T23:59:59.000Z

    We analyze the dynamical expansion of the HII region and outer photodissociation region (PDR) around a massive star by solving the UV and FUV radiation transfer and the thermal and chemical processes in a time-dependent hydrodynamics code. We focus on the physical structure of the shell swept up by the shock front (SF) preceding the ionization front (IF). After the IF reaches the initial Stromgren radius, the SF emerges in front of the IF and the geometrically thin shell bounded with the IF and the SF is formed. The gas density inside the shell is about 10-100 times as high as the ambient gas density. Initially the dissociation fronts expands faster than IF and the PDR is formed outside the HII region. Thereafter the IF and SF gradually overtakes the proceeding dissociation fronts (DFs), and eventually DFs are taken in the shell. The chemical composition within the shell is initially atomic, but hydrogen and carbon monoxide molecules are gradually formed. This is partly because the IF and SF overtake DFs and SF enters the molecular region, and partly because the reformation timescales of the molecules become shorter than the dynamical timescale. The gas shell becomes dominated by the molecular gas by the time of gravitational fragmentation, which agrees with some recent observations. A simple estimation of star formation rate in the shell can provide a significant star formation rate in our galaxy.

  6. High-gravity central stars

    E-Print Network [OSTI]

    Thomas Rauch

    2006-07-11T23:59:59.000Z

    NLTE spectral analyses of high-gravity central stars by means of state-of-the-art model atmosphere techniques provide information about the precursor AGB stars. The hydrogen-deficient post-AGB stars allow investigations on the intershell matter which is apparently exhibited at the stellar surface. We summarize recent results from imaging, spectroscopy, and spectropolarimetry.

  7. Tidal disruptions in circumbinary discs (I): Star formation, dynamics, and binary evolution

    E-Print Network [OSTI]

    Pau Amaro-Seoane; Patrick Brem; Jorge Cuadra

    2012-12-11T23:59:59.000Z

    In our current interpretation of the hierarchical structure of the universe it is well established that galaxies collide and merge with each other during their lifetime. If massive black holes (MBHs) reside in galactic centres, we expect them to form binaries in galactic nuclei surrounded by a circumbinary disc. If cooling is efficient enough, the gas in the disc will clump and trigger stellar formation in situ. In this first paper we address the evolution of the binary under the influence of the newly formed stars, which form individually and also clustered. We use SPH techniques to evolve the gas in the circumbinary disc and to study the phase of star formation. When the amount of gas in the disc is negligible, we further evolve the system with a high-accurate direct-summation $N-$body code to follow the evolution of the stars, the innermost binary and tidal disruption events (TDEs). For this, we modify the direct N-body code to (i) include treatment of TDEs and to (ii) include "gas cloud particles" that mimic the gas, so that the stellar clusters do not disolve when we follow their infall on to the MBHs. We find that the amount of stars disrupted by either infalling stellar clusters or individual stars is as large as 10^{-4}/yr per binary, higher than expected for typical galaxies.

  8. Recent X-ray Observations and the Evolution of Hot Gas in Elliptical Galaxies: Evidence for Circumgalactic Gas

    E-Print Network [OSTI]

    Fabrizio Brighenti; William G. Mathews

    1997-10-18T23:59:59.000Z

    X-ray emitting gaseous halos, such as that in elliptical galaxies like NGC 4472, cannot have been produced solely from gas expelled from galactic stars. In traditional models for the evolution of hot interstellar gas (cooling flows) in ellipticals, the galaxies are assumed to have been cleared of gas by SNII-driven winds at some early time then gas is subsequently replenished by mass loss from an evolving population of old stars. To test this, we accurately determine the stellar and dark halo mass of NGC 4472 using hydrostatic equilibrium, then solve the standard time-dependent cooling flow equations to recover the observed hot gas temperature and density distributions when evolved to the present time. This procedure fails: the computed gas density gradient is too steep, the total gas mass is too low, and the gas temperatures are much too low. All variants on this basic procedure also fail: increasing the SNIa rate, using the mass dropout assumption, arbitrarily adjusting uncertain coefficients, etc. However, agreement is achieved if the galaxy is supplied with additional, spatially-extended hot gas early in its evolution. This old ``circumgalactic'' gas can be retained to the present time and may be related to cosmological ``secondary infall''.

  9. Energy generation in stars

    E-Print Network [OSTI]

    B. V. Vasiliev

    2001-10-29T23:59:59.000Z

    It is a current opinion that thermonuclear fusion is the main source of the star activity. It is shown below that this source is not unique. There is another electrostatic mechanism of the energy generation which accompanies thermonuclear fusion. Probably, this approach can solve the solar neutrino problem.

  10. Accretion of dust grains as a possible origin of metal-poor stars with low alpha/Fe ratios

    E-Print Network [OSTI]

    Shigeyama, T; Shigeyama, Toshikazu; Tsujimoto, Takuji

    2003-01-01T23:59:59.000Z

    The origin of low alpha/Fe ratios in some metal-poor stars, so called low-alpha stars, is discussed. It is found that most of low-alpha stars in the Galaxy are on the main-sequence. This strongly suggests that these stars suffered from external pollution. It is also found that the abundance ratios Zn/Fe of low-alpha stars both in the Galaxy and in dwarf spheroidal galaxies are lower than the average value of Galactic halo stars whereas damped Ly alpha absorbers have higher ratios. This implies that some low-alpha stars accreted matter depleted from gas onto dust grains. To explain the features in these low-alpha stars, we have proposed that metal-poor stars harboring planetary systems are the origin of these low-alpha stars. Stars engulfing a small fraction of planetesimals enhance the surface content of Fe to exhibit low alpha/Fe ratios on their surfaces while they are on the main-sequence, because dwarfs have shallow surface convection zones where the engulfed matter is mixed. After the stars leave the main...

  11. Georgia Tech Dangerous Gas

    E-Print Network [OSTI]

    Sherrill, David

    1 Georgia Tech Dangerous Gas Safety Program March 2011 #12;Georgia Tech Dangerous Gas Safety.......................................................................................................... 5 6. DANGEROUS GAS USAGE REQUIREMENTS................................................. 7 6.1. RESTRICTED PURCHASE/ACQUISITION RULES: ................................................ 7 7. FLAMMABLE GAS

  12. FORMING AN O STAR VIA DISK ACCRETION?

    SciTech Connect (OSTI)

    Qiu Keping [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Zhang Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Beuther, Henrik; Fallscheer, Cassandra, E-mail: kqiu@mpifr-bonn.mpg.de [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2012-09-10T23:59:59.000Z

    We present a study of outflow, infall, and rotation in a {approx}10{sup 5} L{sub Sun} star-forming region, IRAS 18360-0537, with Submillimeter Array and IRAM 30 m observations. The 1.3 mm continuum map shows a 0.5 pc dust ridge, of which the central compact part has a mass of {approx}80 M{sub Sun} and harbors two condensations, MM1 and MM2. The CO (2-1) and SiO (5-4) maps reveal a biconical outflow centered at MM1, which is a hot molecular core (HMC) with a gas temperature of 320 {+-} 50 K and a mass of {approx}13 M{sub Sun }. The outflow has a gas mass of 54 M{sub Sun} and a dynamical timescale of 8 Multiplication-Sign 10{sup 3} yr. The kinematics of the HMC are probed by high-excitation CH{sub 3}OH and CH{sub 3}CN lines, which are detected at subarcsecond resolution and unveil a velocity gradient perpendicular to the outflow axis, suggesting a disk-like rotation of the HMC. An infalling envelope around the HMC is evidenced by CN lines exhibiting a profound inverse P Cygni profile, and the estimated mass infall rate, 1.5 Multiplication-Sign 10{sup -3} M{sub Sun} yr{sup -1}, is well comparable to that inferred from the mass outflow rate. A more detailed investigation of the kinematics of the dense gas around the HMC is obtained from the {sup 13}CO and C{sup 18}O (2-1) lines; the position-velocity diagrams of the two lines are consistent with the model of a free-falling and Keplerian-like rotating envelope. The observations suggest that the protostar of a current mass {approx}10 M{sub Sun} embedded within MM1 will develop into an O star via disk accretion and envelope infall.

  13. Environmental Impact of the Texas LoanSTAR Program

    E-Print Network [OSTI]

    Athar, A.; Abbas, M.; Haberl, J. S.; Turner, W. D.; Claridge, D. E.; Harvey, T.

    1998-01-01T23:59:59.000Z

    /MCF of natural gas. Emission factors from the Environmental Protection Agency's report (EPA 1992) are then used to translate savings in natural gas to environmental emissions reductions. At the LoanSTAR sites, all the boilers have uncontrolled burners (no... pollutants considered in this analysis are SO2, COz and NO,. Carbon dioxide (COz) is one of the major green house gases and is responsible for the green ' One (1) site (Ward Memorial Hospital) is not included in Tables 3.4 & 5 as it only had demand...

  14. Thermodynamic functions of degenerate magnetized electron gas

    SciTech Connect (OSTI)

    Skobelev, V. V., E-mail: v.skobelev@inbox.ru [Moscow State Industrial University (Russian Federation)

    2011-11-15T23:59:59.000Z

    The Fermi energy, pressure, internal energy, entropy, and heat capacity of completely degenerate relativistic electron gas are calculated by numerical methods. It is shown that the maximum admissible magnetic field on the order of 10{sup 9} G in white dwarfs increases the pressure by a factor of 1.06 in the central region, where the electron concentration is {approx}10{sup 33} cm{sup -3}, while the equilibrium radius increases by approximately a factor of 1.03, which obviously cannot be observed experimentally. A magnetic field of {approx}10{sup 8} G or lower has no effect on the pressure and other thermodynamic functions. It is also shown that the contribution of degenerate electron gas to the total pressure in neutron stars is negligible compared to that of neutron gas even in magnetic fields with a maximum induction {approx}10{sup 17} G possible in neutron stars. The neutron beta-decay forbiddeness conditions in a superstrong magnetic field are formulated. It is assumed that small neutron stars have such magnetic fields and that pulsars with small periods are the most probable objects that can have super-strong magnetic fields.

  15. Misalignment between cold gas and stellar components in early-type galaxies

    E-Print Network [OSTI]

    Wong, O Ivy; Józsa, G I G; Urry, C M; Lintott, C J; Simmons, B D; Kaviraj, S; Masters, K L

    2015-01-01T23:59:59.000Z

    Recent work suggests blue ellipticals form in mergers and migrate quickly from the blue cloud of star-forming galaxies to the red sequence of passively evolving galaxies, perhaps as a result of black hole feedback. Such rapid reddening of stellar populations implies that large gas reservoirs in the pre-merger star-forming pair must be depleted on short time scales. Here we present pilot observations of atomic hydrogen gas in four blue early-type galaxies that reveal increasing spatial offsets between the gas reservoirs and the stellar components of the galaxies, with advancing post-starburst age. Emission line spectra show associated nuclear activity in two of the merged galaxies, and in one case radio lobes aligned with the displaced gas reservoir. These early results suggest that a kinetic process (possibly feedback from black hole activity) is driving the quick truncation of star formation in these systems, rather than a simple exhaustion of gas supply.

  16. Energy Star for Hospitals 2011 Update: Progression or Regression?

    E-Print Network [OSTI]

    Travis, B.

    2012-01-01T23:59:59.000Z

    Agency created Energy Star for Buildings, as well as Portfolio Manager, an online benchmarking tool which allowed users to input their utility bills while simultaneously tracking important energy performance metrics for their building..., such as the Energy Utilization Intensity (E.U.I.) and Energy Cost Intensity (E.C.I.). Since its inception, Portfolio Manager has also added the ability to track water consumption, as well as greenhouse gas emissions. As of September of 2011, the U.S. EPA...

  17. Self-Regulated Fueling of Galaxy Centers: Evidence for Star-Formation Feedback in IC342's Nucleus

    E-Print Network [OSTI]

    E. Schinnerer; T. Boeker; D. S. Meier; D. Calzetti

    2008-08-06T23:59:59.000Z

    Using new, high-resolution interferometric observations of the CO and HCN molecules, we directly compare the molecular and ionized components of the interstellar medium in the center of the nearby spiral galaxy IC342, on spatial scales of ~ 10pc. The morphology of the tracers suggests that the molecular gas flow caused by a large-scale stellar bar has been strongly affected by the mechanical feedback from recent star formation activity within the central 100pc in the nucleus of the galaxy. Possibly, stellar winds and/or supernova shocks originating in the nuclear star cluster have compressed, and likely pushed outward, the infalling molecular gas, thus significantly reducing the gas supply to the central 10pc. Although our analysis currently lacks kinematic confirmation due to the face-on orientation of IC342, the described scenario is supported by the generally observed repetitive nature of star formation in the nuclear star clusters of late-type spiral galaxies.

  18. ENERGY STAR Webinar: Financing Energy Efficient Upgrades with...

    Broader source: Energy.gov (indexed) [DOE]

    ENERGY STAR Webinar: Financing Energy Efficient Upgrades with ENERGY STAR ENERGY STAR Webinar: Financing Energy Efficient Upgrades with ENERGY STAR October 21, 2014 2:00PM to...

  19. Cooling, AGN Feedback and Star Formation in Simulated Cool-Core Galaxy Clusters

    E-Print Network [OSTI]

    Li, Yuan; Ruszkowski, Mateusz; Voit, G Mark; O'Shea, Brian W; Donahue, Megan

    2015-01-01T23:59:59.000Z

    Numerical simulations of active galactic nuclei (AGN) feedback in cool-core galaxy clusters have successfully avoided classical cooling flows, but often produce too much cold gas. We perform adaptive mesh simulations that include momentum-driven AGN feedback, self-gravity, star formation and stellar feedback, focusing on the interplay between cooling, AGN heating and star formation in an isolated cool-core cluster. Cold clumps triggered by AGN jets and turbulence form filamentary structures tens of kpc long. This cold gas feeds both star formation and the supermassive black hole (SMBH), triggering an AGN outburst that increases the entropy of the ICM and reduces its cooling rate. Within 1-2 Gyr, star formation completely consumes the cold gas, leading to a brief shutoff of the AGN. The ICM quickly cools and redevelops multiphase gas, followed by another cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three such cycles. There is good agreement between our simulated cluster and the observations...

  20. ENERGY STAR Webinar: Financing Energy Efficient Upgrades with ENERGY STAR

    Broader source: Energy.gov [DOE]

    Hosted by ENERGY STAR, this webinar will show how public sector organizations are improving energy efficiency with innovative solutions to financial barriers.

  1. Triggered Star Formation in the Environment of Young Massive Stars

    E-Print Network [OSTI]

    M. Gritschneder; T. Naab; F. Heitsch; A. Burkert

    2006-09-26T23:59:59.000Z

    Recent observations with the Spitzer Space Telescope show clear evidence that star formation takes place in the surrounding of young massive O-type stars, which are shaping their environment due to their powerful radiation and stellar winds. In this work we investigate the effect of ionising radiation of massive stars on the ambient interstellar medium (ISM): In particular we want to examine whether the UV-radiation of O-type stars can lead to the observed pillar-like structures and can trigger star formation. We developed a new implementation, based on a parallel Smooth Particle Hydrodynamics code (called IVINE), that allows an efficient treatment of the effect of ionising radiation from massive stars on their turbulent gaseous environment. Here we present first results at very high resolution. We show that ionising radiation can trigger the collapse of an otherwise stable molecular cloud. The arising structures resemble observed structures (e.g. the pillars of creation in the Eagle Nebula (M16) or the Horsehead Nebula B33). Including the effect of gravitation we find small regions that can be identified as formation places of individual stars. We conclude that ionising radiation from massive stars alone can trigger substantial star formation in molecular clouds.

  2. Fuel gas conditioning process

    DOE Patents [OSTI]

    Lokhandwala, Kaaeid A. (Union City, CA)

    2000-01-01T23:59:59.000Z

    A process for conditioning natural gas containing C.sub.3+ hydrocarbons and/or acid gas, so that it can be used as combustion fuel to run gas-powered equipment, including compressors, in the gas field or the gas processing plant. Compared with prior art processes, the invention creates lesser quantities of low-pressure gas per unit volume of fuel gas produced. Optionally, the process can also produce an NGL product.

  3. THE ADVANCED CAMERA FOR SURVEYS NEARBY GALAXY SURVEY TREASURY. VI. THE ANCIENT STAR-FORMING DISK OF NGC 404

    SciTech Connect (OSTI)

    Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Stilp, Adrienne [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Dolphin, Andrew [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85706 (United States); Seth, Anil C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Weisz, Daniel; Skillman, Evan, E-mail: ben@astro.washington.ed, E-mail: jd@astro.washington.ed, E-mail: stephanie@astro.washington.ed, E-mail: roskar@astro.washington.ed, E-mail: dolphin@raytheon.co, E-mail: aseth@cfa.harvard.ed, E-mail: dweisz@astro.umn.ed, E-mail: skillman@astro.umn.ed [Department of Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)

    2010-06-10T23:59:59.000Z

    We present HST/WFPC2 observations across the disk of the nearby isolated dwarf S0 galaxy NGC 404, which hosts an extended gas disk. The locations of our fields contain a roughly equal mixture of bulge and disk stars. All of our resolved stellar photometry reaches m {sub F814W} = 26 (M {sub F814W} = -1.4), which covers 2.5 mag of the red giant branch and main-sequence stars with ages <300 Myr. Our deepest field reaches m {sub F814W} = 27.2 (M {sub F814W} = -0.2), sufficient to resolve the red clump and main-sequence stars with ages <500 Myr. Although we detect trace amounts of star formation at times more recent than 10 Gyr ago for all fields, the proportion of red giant stars to asymptotic giants and main-sequence stars suggests that the disk is dominated by an ancient (>10 Gyr) population. Detailed modeling of the color-magnitude diagram suggests that {approx}70% of the stellar mass in the NGC 404 disk formed by z {approx} 2 (10 Gyr ago) and at least {approx}90% formed prior to z {approx} 1 (8 Gyr ago). These results indicate that the stellar populations of the NGC 404 disk are on average significantly older than those of other nearby disk galaxies, suggesting that early- and late-type disks may have different long-term evolutionary histories, not simply differences in their recent star formation rates. Comparisons of the spatial distribution of the young stellar mass and FUV emission in Galaxy Evolution Explorer images show that the brightest FUV regions contain the youngest stars, but that some young stars (<160 Myr) lie outside of these regions. FUV luminosity appears to be strongly affected by both age and stellar mass within individual regions. Finally, we use our measurements to infer the relationship between the star formation rate and the gas density of the disk at previous epochs. We find that most of the history of the NGC 404 disk is consistent with star formation that has decreased with the gas density according to the Schmidt law. However, {approx} 0.5-1 Gyr ago, the star formation rate was unusually low for the inferred gas density, consistent with the possibility that there was a gas accretion event that reignited star formation {approx}0.5 Gyr ago. Such an event could explain why this S0 galaxy hosts an extended gas disk.

  4. The Magnetic Fields of Classical T Tauri Stars

    E-Print Network [OSTI]

    Christopher M. Johns-Krull

    2007-04-23T23:59:59.000Z

    We report new magnetic field measurements for 14 classical T Tauri stars (CTTSs). We combine these data with one previous field determination in order to compare our observed field strengths with the field strengths predicted by magnetospheric accretion models. We use literature data on the stellar mass, radius, rotation period, and disk accretion rate to predict the field strength that should be present on each of our stars according to these magnetospheric accretion models. We show that our measured field values do not correlate with the field strengths predicted by simple magnetospheric accretion theory. We also use our field strength measurements and literature X-ray luminosity data to test a recent relationship expressing X-ray luminosity as a function of surface magnetic flux derived from various solar feature and main sequence star measurements. We find that the T Tauri stars we have observed have weaker than expected X-ray emission by over an order of magnitude on average using this relationship. We suggest the cause for this is actually a result of the very strong fields on these stars which decreases the efficiency with which gas motions in the photosphere can tangle magnetic flux tubes in the corona.

  5. Nuclear Star Clusters and Bulges

    E-Print Network [OSTI]

    Cole, David R

    2015-01-01T23:59:59.000Z

    Nuclear star clusters are among the densest stellar systems known and are common in both early- and late-type galaxies. They exhibit scaling relations with their host galaxy which may be related to those of supermassive black holes. These may therefore help us to unravel the complex physical processes occurring at the centres of galaxies. The properties of nuclear stellar systems suggest that their formation requires both dissipational and dissipationless processes. They have stellar populations of different ages, from stars as old as their host galaxy to young stars formed in the last 100 Myr. Therefore star formation must be happening either directly in the nuclear star cluster or in its vicinity. The secular processes that fuel the formation of pseudobulges very likely also contributes to nuclear star cluster growth.

  6. Spontaneous Scalarization and Boson Stars

    E-Print Network [OSTI]

    A. W. Whinnett

    2000-02-17T23:59:59.000Z

    We study spontaneous scalarization in Scalar-Tensor boson stars. We find that scalarization does not occur in stars whose bosons have no self-interaction. We introduce a quartic self-interaction term into the boson Lagrangian and show that when this term is large, scalarization does occur. Strong self-interaction leads to a large value of the compactness (or sensitivity) of the boson star, a necessary condition for scalarization to occur, and we derive an analytical expression for computing the sensitivity of a boson star in Brans-Dicke theory from its mass and particle number. Next we comment on how one can use the sensitivity of a star in any Scalar-Tensor theory to determine how its mass changes when it undergoes gravitational evolution. Finally, in the Appendix, we derive the most general form of the boson wavefunction that minimises the energy of the star when the bosons carry a U(1) charge.

  7. New Abundansec From Very Old Stars

    E-Print Network [OSTI]

    Hansen, T; Christlieb, N; Yong, D; Beers, T C; Andersen, J

    2015-01-01T23:59:59.000Z

    Metal-poor stars hold the fossil record of the Galactic chemical evolution and nucleosynthesis processes that took place at the earliest times in the history of our Galaxy. From detailed abundance studies of low mass, extremely metal-poor stars ([Fe/H] capture. The sample includes some of the most metal-poor stars ([Fe/H] capture elements, and also a number of stars enhanced in carbon. The so called CEMP (carbon enhanced metal-poor) stars, these stars make up ~20% of the stars with [Fe/H] < -3, and 80% of the stars with [Fe/H] < -4.5. The progenitors of CEMP stars is still ...

  8. Origins of Massive Field Stars in the Galactic Center: a Spectroscopic Study

    E-Print Network [OSTI]

    Dong, Hui; Morris, Mark R; Wang, Q Daniel; Cotera, Angela

    2014-01-01T23:59:59.000Z

    Outside of the known star clusters in the Galactic Center, a large number of evolved massive stars have been detected; but their origins remain uncertain. We present a spectroscopic study of eight such stars, based on new Gemini GNIRS and NIFS near-infrared observations. This work has led to the discovery of a new O If+ star. We compare the reddening-corrected J-K vs K diagram for our stars with the massive ones in the Arches cluster and use stellar evolutionary tracks to constrain their ages and masses. The radial velocities of both the stars and their nearby H II regions are also reported. All of the stars are blueshifted relative to the Arches cluster by > 50 km/s. We find that our source P35 has a velocity consistent with that of the surrounding molecular gas. The velocity gradient of nearby ionized gas along the Gemini GNIRS long slit, relative to P35 and the adjacent -30-0 km/s molecular cloud, can best be explained by a pressure-driven flow model. Thus, P35 most likely formed in situ. Three more of our...

  9. Chemo-Dynamical SPH code for evolution of star forming disk galaxies

    E-Print Network [OSTI]

    Peter Berczik

    1999-07-27T23:59:59.000Z

    A new Chemo-Dynamical Smoothed Particle Hydrodynamic (CD-SPH) code is presented. The disk galaxy is described as a multi-fragmented gas and star system, embedded in a cold dark matter halo with a rigid potential field. The star formation (SF) process, SNII, SNIa and PN events, and the chemical enrichment of gas, have all been considered within the framework of the standard SPH model, which we use to describe the dynamical and chemical evolution of triaxial disk-like galaxies. It is found that such approach provides a realistic description of the process of formation, chemical and dynamical evolution of disk galaxies over a cosmological timescale.

  10. Modeling the star formation in galaxies using the Chemo - dynamical SPH code

    E-Print Network [OSTI]

    Peter Berczik

    2000-07-19T23:59:59.000Z

    A new Chemo - Dynamical Smoothed Particle Hydrodynamic (CD - SPH) code is presented. The disk galaxy is described as a multi - fragmented gas and star system, embedded in a cold dark matter halo. The star formation (SF) process, SNII, SNIa and PN events as well as chemical enrichment of gas have been considered within the framework of the standard SPH model. Using this model we describe the dynamical and chemical evolution of triaxial disk - like galaxies. It is found that such approach provides a realistic description of the process of formation, chemical and dynamical evolution of disk galaxies over a cosmological timescale.

  11. THE ADVANCED CAMERA FOR SURVEYS NEARBY GALAXY SURVEY TREASURY. IV. THE STAR FORMATION HISTORY OF NGC 2976

    SciTech Connect (OSTI)

    Williams, Benjamin F.; Dalcanton, Julianne J.; Stilp, Adrienne; Gilbert, Karoline M.; Roskar, Rok; Gogarten, Stephanie M. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Seth, Anil C. [CfA Fellow, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Weisz, Daniel; Skillman, Evan [Department of Astronomy, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States); Dolphin, Andrew [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85706 (United States); Holtzman, Jon, E-mail: ben@astro.washington.ed, E-mail: jd@astro.washington.ed, E-mail: roskar@astro.washington.ed, E-mail: stephanie@astro.washington.ed, E-mail: aseth@cfa.harvard.ed, E-mail: dweisz@astro.umn.ed, E-mail: skillman@astro.umn.ed, E-mail: dolphin@raytheon.co, E-mail: holtz@nmsu.ed [Department of Astronomy, New Mexico State University, Box 30001, 1320 Frenger St., Las Cruces, NM 88003 (United States)

    2010-01-20T23:59:59.000Z

    We present resolved stellar photometry of NGC 2976 obtained with the Advanced Camera for Surveys (ACS) as part of the ACS Nearby Galaxy Survey Treasury (ANGST) program. The data cover the radial extent of the major axis of the disk out to 6 kpc, or approx6 scale lengths. The outer disk was imaged to a depth of M{sub F606W} approx 1, and an inner field was imaged to the crowding limit at a depth of M{sub F606W} approx -1. Through detailed analysis and modeling of the resulting color-magnitude diagrams, we have reconstructed the star formation history (SFH) of the stellar populations currently residing in these portions of the galaxy, finding similar ancient populations at all radii but significantly different young populations at increasing radii. In particular, outside of the well-measured break in the disk surface brightness profile, the age of the youngest population increases with distance from the galaxy center, suggesting that star formation is shutting down from the outside-in. We use our measured SFH, along with H I surface density measurements, to reconstruct the surface density profile of the disk during previous epochs. Comparisons between the recovered star formation rates and reconstructed gas densities at previous epochs are consistent with star formation following the Schmidt law during the past 0.5 Gyr, but with a drop in star formation efficiency at low gas densities, as seen in local galaxies at the present day. The current rate and gas density suggest that rapid star formation in NGC 2976 is currently in the process of ceasing from the outside-in due to gas depletion. This process of outer disk gas depletion and inner disk star formation was likely triggered by an interaction with the core of the M81 group approx>1 Gyr ago that stripped the gas from the galaxy halo and/or triggered gas inflow from the outer disk toward the galaxy center.

  12. Surface abundances of ON stars

    E-Print Network [OSTI]

    Martins, F; Palacios, A; Howarth, I; Georgy, C; Walborn, N R; Bouret, J -C; Barba, R

    2015-01-01T23:59:59.000Z

    Massive stars burn hydrogen through the CNO cycle during most of their evolution. When mixing is efficient, or when mass transfer in binary systems happens, chemically processed material is observed at the surface of O and B stars. ON stars show stronger lines of nitrogen than morphologically normal counterparts. Whether this corresponds to the presence of material processed through the CNO cycle or not is not known. Our goal is to answer this question. We perform a spectroscopic analysis of a sample of ON stars with atmosphere models. We determine the fundamental parameters as well as the He, C, N, and O surface abundances. We also measure the projected rotational velocities. We compare the properties of the ON stars to those of normal O stars. We show that ON stars are usually helium-rich. Their CNO surface abundances are fully consistent with predictions of nucleosynthesis. ON stars are more chemically evolved and rotate - on average - faster than normal O stars. Evolutionary models including rotation cann...

  13. Creating a Star on Earth

    Broader source: Energy.gov [DOE]

    At the Energy Department's Princeton Plasma Physics Lab, scientists are trying to accomplish what was once considered the realm of science fiction: creating a star on Earth.

  14. Home Performance with Energy Star

    Broader source: Energy.gov [DOE]

    Through the Home Performance with Energy Star program, Focus on Energy offers instant rewards for installing select recommended efficiency measures following a home energy audit. Energy consultants...

  15. Streamlining ENERGY STAR Appliance Testing

    Broader source: Energy.gov [DOE]

    To save taxpayer dollars and help lower the costs of innovative energy-efficient technologies, the Energy Department is streamlining ENERGY STAR testing for appliances.

  16. A Mosque Among the Stars

    E-Print Network [OSTI]

    Ahmad, Muhammad Aurangzeb; Khan, Ahmad

    2007-01-04T23:59:59.000Z

    A Mosque Among The Stars was the first anthology that dealt with the subject of Muslim characters and/or Islamic themes and Science Fiction....

  17. OXYGEN GAS-PHASE ABUNDANCE REVISITED M. K. Andre,1,2

    E-Print Network [OSTI]

    Howk, Jay Christopher

    OXYGEN GAS-PHASE ABUNDANCE REVISITED M. K. Andre´,1,2 C. M. Oliveira,2 J. C. Howk,2 R. Ferlet,1 J gas-phase oxygen abundance along the sight lines toward 19 early-type Galactic stars at an average magÀ1 with a standard deviation of 15% is consistent with previous surveys. The mean oxygen abundance

  18. (Astro)Physics 343 Lecture # 8: Green Bank trip + gas dynamics

    E-Print Network [OSTI]

    Baker, Andrew J.

    matter (i.e., dark matter). #12; A heretical alternative? A few bold souls have pointed out that once/T. #12; Gas dynamics: a Keplerian example From Herrnstein et al. (1999): water masers tracing orbital, based on the central concentration of luminous matter (stars and gas): #12; Rotation curves

  19. (Astro)Physics 343 Lecture # 8: Green Bank trip; gas dynamics

    E-Print Network [OSTI]

    Baker, Andrew J.

    matter (i.e., dark matter). #12; A heretical alternative? A few bold souls have pointed out that once/T. #12; Gas dynamics: a Keplerian example From Herrnstein et al. (1999): water masers tracing orbital, based on the central concentration of luminous matter (stars and gas): #12; Rotation curves

  20. Covered Product Category: Residential Gas Storage Water Heaters

    Broader source: Energy.gov [DOE]

    FEMP provides acquisition guidance across a variety of product categories, including gas storage water heaters, which are an ENERGY STAR®-qualified product category. Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.

  1. Beryllium abundances in metal-poor stars

    E-Print Network [OSTI]

    K. F. Tan; J. R. Shi; G. Zhao

    2008-10-15T23:59:59.000Z

    We have determined beryllium abundances for 25 metal-poor stars based on the high resolution and high signal-to-noise ratio spectra from the VLT/UVES database. Our results confirm that Be abundances increase with Fe, supporting the global enrichment of Be in the Galaxy. Oxygen abundances based on [O I] forbidden line implies a linear relation with a slope close to one for the Be vs. O trend, which indicates that Be is probably produced in a primary process. Some strong evidences are found for the intrinsic dispersion of Be abundances at a given metallicity. The deviation of HD132475 and HD126681 from the general Be vs. Fe and Be vs. O trend favours the predictions of the superbubble model, though the possibility that such dispersion originates from the inhomogeneous enrichment in Fe and O of the protogalactic gas cannot be excluded.

  2. Cavitation from bulk viscosity in neutron stars and quark stars

    E-Print Network [OSTI]

    Jes Madsen

    2009-09-30T23:59:59.000Z

    The bulk viscosity in quark matter is sufficiently high to reduce the effective pressure below the corresponding vapor pressure during density perturbations in neutron stars and strange stars. This leads to mechanical instability where the quark matter breaks apart into fragments comparable to cavitation scenarios discussed for ultra-relativistic heavy-ion collisions. Similar phenomena may take place in kaon-condensed stellar cores. Possible applications to compact star phenomenology include a new mechanism for damping oscillations and instabilities, triggering of phase transitions, changes in gravitational wave signatures of binary star inspiral, and astrophysical formation of strangelets. At a more fundamental level it points to the possible inadequacy of a hydrodynamical treatment of these processes in compact stars.

  3. Dwarf galaxies with ionizing radiation feedback. II. Spatially resolved star formation relation

    SciTech Connect (OSTI)

    Kim, Ji-hoon; Krumholz, Mark R.; Goldbaum, Nathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Wise, John H. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Turk, Matthew J. [Department of Astronomy and Astrophysics, Columbia University, New York, NY 10027 (United States); Abel, Tom, E-mail: me@jihoonkim.org [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States)

    2013-12-10T23:59:59.000Z

    We investigate the spatially resolved star formation relation using a galactic disk formed in a comprehensive high-resolution (3.8 pc) simulation. Our new implementation of stellar feedback includes ionizing radiation as well as supernova explosions, and we handle ionizing radiation by solving the radiative transfer equation rather than by a subgrid model. Photoheating by stellar radiation stabilizes gas against Jeans fragmentation, reducing the star formation rate (SFR). Because we have self-consistently calculated the location of ionized gas, we are able to make simulated, spatially resolved observations of star formation tracers, such as H? emission. We can also observe how stellar feedback manifests itself in the correlation between ionized and molecular gas. Applying our techniques to the disk in a galactic halo of 2.3 × 10{sup 11} M {sub ?}, we find that the correlation between SFR density (estimated from mock H? emission) and H{sub 2} density shows large scatter, especially at high resolutions of ?75 pc that are comparable to the size of giant molecular clouds (GMCs). This is because an aperture of GMC size captures only particular stages of GMC evolution and because H? traces hot gas around star-forming regions and is displaced from the H{sub 2} peaks themselves. By examining the evolving environment around star clusters, we speculate that the breakdown of the traditional star formation laws of the Kennicutt-Schmidt type at small scales is further aided by a combination of stars drifting from their birthplaces and molecular clouds being dispersed via stellar feedback.

  4. Gas Storage Act (Illinois)

    Broader source: Energy.gov [DOE]

    Any corporation which is engaged in or desires to engage in, the distribution, transportation or storage of natural gas or manufactured gas, which gas, in whole or in part, is intended for ultimate...

  5. Gas Companies Program (Tennessee)

    Broader source: Energy.gov [DOE]

    The Gas Companies program is a set of rules that encourage the development of the natural gas industry in Tennessee. They empower gas companies to lay piped and extend conductors through the...

  6. Gas Utilities (Maine)

    Broader source: Energy.gov [DOE]

    Rules regarding the production, sale, and transfer of manufactured gas will also apply to natural gas. This section regulates natural gas utilities that serve ten or more customers, more than one...

  7. Gas Utilities (New York)

    Broader source: Energy.gov [DOE]

    This chapter regulates natural gas utilities in the State of New York, and describes standards and procedures for gas meters and accessories, gas quality, line and main extensions, transmission and...

  8. Future of Natural Gas

    Office of Environmental Management (EM)

    of Natural Gas Bill Eisele, CEM SC Electric & Gas Co Hosted by: FEDERAL UTILITY PARTNERSHIP WORKING GROUP SEMINAR November 5-6, 2014 Cape Canaveral. Florida Agenda * Gas Facts *...

  9. Industrial Gas Turbines

    Broader source: Energy.gov [DOE]

    A gas turbine is a heat engine that uses high-temperature, high-pressure gas as the working fluid. Part of the heat supplied by the gas is converted directly into mechanical work. High-temperature,...

  10. Supervisory Natural Gas Analyst

    Broader source: Energy.gov [DOE]

    The Department of Energys Office of Fossil Energy, Office of Oil and Natural Gas, Office of Oil and Gas Global Security and Supply (FE) is responsible for regulating natural gas imports and exports...

  11. Condensation and Magnetization of the Relativistic Bose Gas

    E-Print Network [OSTI]

    P. Elmfors; P. Liljenberg; D. Persson; B. -S. Skagerstam

    1994-07-22T23:59:59.000Z

    We present a simple proof of the absence of Bose--Einstein condensation of a relativistic boson gas, in any finite local magnetic field in less than five dimensions. We show that the relativistic charged boson gas exhibit a genuine Meissner--Ochsenfeld effect of the Schafroth form at fixed supercritical density. As in the well--known non--relativistic case, this total expulsion of a magnetic field is caused by the condensation of the Bose gas at vanishing magnetic field. The result is discussed in the context of kaon condensation in neutron stars.

  12. On rotating star solutions to non-isentropic Euler-Poisson equations

    E-Print Network [OSTI]

    Yilun Wu

    2014-11-04T23:59:59.000Z

    This paper investigates rotating star solutions to the Euler-Poisson equations with a non-isentropic equation of state. As a first step, the equation for gas density with a prescribed entropy and angular velocity distribution is studied. The resulting elliptic equation is solved either by the method of sub and supersolutions or by a variational method, depending on the value of the adiabatic index. The reverse problem of determining angular velocity from gas density is also considered.

  13. POLYCYCLIC AROMATIC HYDROCARBONS, IONIZED GAS, AND MOLECULAR HYDROGEN IN BRIGHTEST CLUSTER GALAXIES OF COOL-CORE CLUSTERS OF GALAXIES

    SciTech Connect (OSTI)

    Donahue, Megan; Mark Voit, G.; Hoffer, Aaron [Physics and Astronomy Department, Michigan State University, East Lansing, MI 48824 (United States); De Messieres, Genevieve E.; O'Connell, Robert W. [Astronomy Department, University of Virginia, Charlottesville, VA (United States); McNamara, Brian R. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Nulsen, Paul E. J., E-mail: donahue@pa.msu.edu, E-mail: voit@pa.msu.edu, E-mail: hofferaa@msu.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2011-05-01T23:59:59.000Z

    We present measurements of 5-25 {mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of nine cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray-emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission-line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H{sub 2} rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as somewhat higher ratios of 70 {mu}m/24 {mu}m luminosities. Our analysis suggests that while star formation processes dominate the heating of the dust and PAHs, a heating process consistent with suprathermal electron heating from the hot gas, distinct from star formation, is heating the molecular gas and contributing to the heating of the ionized gas in the galaxies. The survival of PAHs and dust suggests that dusty gas is somehow shielded from significant interaction with the X-ray gas.

  14. Physics of Neutron Star Crusts

    E-Print Network [OSTI]

    N. Chamel; P. Haensel

    2008-12-20T23:59:59.000Z

    The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.

  15. Star formation in the multiverse

    SciTech Connect (OSTI)

    Bousso, Raphael; Leichenauer, Stefan [Center for Theoretical Physics, Department of Physics, University of California, Berkeley, California 94720-7300 (United States) and Lawrence Berkeley National Laboratory, Berkeley, California 94720-8162 (United States)

    2009-03-15T23:59:59.000Z

    We develop a simple semianalytic model of the star formation rate as a function of time. We estimate the star formation rate for a wide range of values of the cosmological constant, spatial curvature, and primordial density contrast. Our model can predict such parameters in the multiverse, if the underlying theory landscape and the cosmological measure are known.

  16. Thermal Evolution of Strange Stars

    E-Print Network [OSTI]

    Zhou Xia; Wang Lingzhi; Zhou Aizhi

    2007-09-03T23:59:59.000Z

    We investigated the thermal evolution of rotating strange stars with the deconfinement heating due to magnetic braking. We consider the stars consisting of either normal quark matter or color-flavor-locked phase. Combining deconfinement heating with magnetic field decay, we find that the thermal evolution curves are identical to pulsar data.

  17. Natural Gas Monthly Update

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    other liquids including biofuels and natural gas liquids. Natural Gas Exploration and reserves, storage, imports and exports, production, prices, sales. Electricity Sales, revenue...

  18. Gas Production Tax (Texas)

    Broader source: Energy.gov [DOE]

    A tax of 7.5 percent of the market value of natural gas produced in the state of Texas is imposed on every producer of gas.

  19. Historical Natural Gas Annual

    U.S. Energy Information Administration (EIA) Indexed Site

    8 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  20. Natural gas dehydration apparatus

    DOE Patents [OSTI]

    Wijmans, Johannes G; Ng, Alvin; Mairal, Anurag P

    2006-11-07T23:59:59.000Z

    A process and corresponding apparatus for dehydrating gas, especially natural gas. The process includes an absorption step and a membrane pervaporation step to regenerate the liquid sorbent.

  1. Historical Natural Gas Annual

    U.S. Energy Information Administration (EIA) Indexed Site

    6 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  2. Historical Natural Gas Annual

    U.S. Energy Information Administration (EIA) Indexed Site

    7 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  3. Fossil Imprints of Outflow from the Galactic Bulge in Elemental Abundances of Metal-Rich Disk Stars

    E-Print Network [OSTI]

    Takuji Tsujimoto

    2007-07-09T23:59:59.000Z

    We explore the elemental abundance features of metal-rich disk stars, highlighting the comparisons made with those of the recently revealed Galactic bulge stars. A similarity between two of the comparisons leads to a new theoretical picture of the bulge-disk connection in the Galaxy, where a supermassive black hole resides at the center. We postulate that a metal-rich outflow, triggered by feedback from a black hole, was generated and quenched the star formation, which had lasted several billion years in the bulge. The expelled gas cooled down in the Galactic halo without escaping from the gravitational potential of the Galaxy. The gas gradually started to accrete to the disk around five billion years ago, corresponding to the time of sun's birth, and replaced a low-metallicity halo gas that had been accreting over nearly ten billion years. The metal-rich infalling gas, whose elemental abundance reflects that of metal-rich bulge stars, mixed with the interstellar gas already present in the disk. Stars formed from the mixture compose the metal-rich stellar disk. This scheme is incorporated into models for chemical evolution of the disk. The resultant elemental features are compatible with the observed abundance trends of metal-rich disk stars, including the upturning feature exhibited in some [X/Fe] ratios, whose interpretation was theoretically puzzling. Furthermore, the predicted abundance distribution function of disk stars covers all observational facts to be considered: (i) the deficiency of metal-poor stars, (ii) the location of peak, and (iii) the extended metal-rich tail up to [Fe/H] ~ +0.4.

  4. Fossil Imprints of Outflow from the Galactic Bulge in Elemental Abundances of Metal-Rich Disk Stars

    E-Print Network [OSTI]

    Tsujimoto, Takuji

    2007-01-01T23:59:59.000Z

    We explore the elemental abundance features of metal-rich disk stars, highlighting the comparisons made with those of the recently revealed Galactic bulge stars. A similarity between two of the comparisons leads to a new theoretical picture of the bulge-disk connection in the Galaxy, where a supermassive black hole resides at the center. We postulate that a metal-rich outflow, triggered by feedback from a black hole, was generated and quenched the star formation, which had lasted several billion years in the bulge. The expelled gas cooled down in the Galactic halo without escaping from the gravitational potential of the Galaxy. The gas gradually started to accrete to the disk around five billion years ago, corresponding to the time of sun's birth, and replaced a low-metallicity halo gas that had been accreting over nearly ten billion years. The metal-rich infalling gas, whose elemental abundance reflects that of metal-rich bulge stars, mixed with the interstellar gas already present in the disk. Stars formed ...

  5. DUST EMISSION AND STAR FORMATION IN STEPHAN'S QUINTET

    SciTech Connect (OSTI)

    Natale, G.; Tuffs, R. J. [Max Planck Institute fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Xu, C. K.; Lu, N. [Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States); Popescu, C. C. [University of Central Lancashire, Preston, PR1 2HE (United Kingdom); Fischera, J. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 Saint George Street, Toronto, ON, M5S 3H8 (Canada); Lisenfeld, U. [Department de Fisica Teorica y del Cosmos, Universidad de Granada, Granada (Spain); Appleton, P. [NASA Herschel Science Center, IPAC, California Institute of Technology, Pasadena, CA 91125 (United States); Dopita, M. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Duc, P.-A. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Dapnia/Service d'Astrophysique, CEA-Saclay, 91191 Gif-sur-Yvette Cedex (France); Gao, Y. [Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China); Reach, W. [Spitzer Science Center, IPAC, California Institute of Technology, Pasadena, CA 91125 (United States); Sulentic, J. [Instituto de Astrofisica de AndalucIa, CSIC, Apdo. 3004, 18080, Granada (Spain); Yun, M., E-mail: giovanni.natale@mpi-hd.mpg.d, E-mail: richard.buffs@mpi-hd.mpg.d [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

    2010-12-10T23:59:59.000Z

    We analyze a comprehensive set of MIR/FIR observations of Stephan's Quintet (SQ), taken with the Spitzer Space Telescope. Our study reveals the presence of a luminous (L{sub IR} {approx} 4.6 x 10{sup 43} erg s{sup -1}) and extended component of infrared dust emission, not connected with the main bodies of the galaxies, but roughly coincident with the X-ray halo of the group. We fitted the inferred dust emission spectral energy distribution of this extended source and the other main infrared emission components of SQ, including the intergalactic shock, to elucidate the mechanisms powering the dust and polycyclic aromatic hydrocarbon emission, taking into account collisional heating by the plasma and heating through UV and optical photons. Combining the inferred direct and dust-processed UV emission to estimate the star formation rate (SFR) for each source we obtain a total SFR for SQ of 7.5 M{sub sun} yr{sup -1}, similar to that expected for non-interacting galaxies with stellar mass comparable to the SQ galaxies. Although star formation in SQ is mainly occurring at, or external to the periphery of the galaxies, the relation of SFR per unit physical area to gas column density for the brightest sources is similar to that seen for star formation regions in galactic disks. We also show that available sources of dust in the group halo can provide enough dust to produce up to L{sub IR} {approx} 10{sup 42} erg s{sup -1} powered by collisional heating. Though a minority of the total infrared emission (which we infer to trace distributed star-formation), this is several times higher than the X-ray luminosity of the halo, so could indicate an important cooling mechanism for the hot intergalactic medium (IGM) and account for the overall correspondence between FIR and X-ray emission. We investigate two potential modes of star formation in SQ consistent with the data, fueled either by gas from a virialized hot IGM continuously accreting onto the group, whose cooling is enhanced by grains injected from an in situ population of intermediate mass stars, or by interstellar gas stripped from the galaxies. The former mode offers a natural explanation for the observed baryon deficiency in the IGM of SQ as well as for the steep L{sub X}-T{sub X} relation of groups such as SQ with lower velocity dispersions.

  6. Massive stars: Feedback effects in the local universe

    E-Print Network [OSTI]

    M. S. Oey; C. J. Clarke

    2007-03-02T23:59:59.000Z

    We examine self-consistent parameterizations of the high-mass stellar population and resulting feedback, including mechanical, radiative, and chemical feedback, as we understand them locally. To date, it appears that the massive star population follows simple power-law clustering that extends down to individual field OB stars, and the robust stellar IMF seems to have a constant upper-mass limit. These properties result in specific patterns in the HII region LF and ionization of the diffuse, warm ionized medium. The resulting SNe generate superbubbles whose size distribution is also described by a simple power law, and from which a galaxy's porosity parameter is easily derived. A critical star-formation threshold can then be estimated, above which the escape of Lyman continuum photons, hot gas, and nucleosynthetic products is predicted. A first comparison with a large H-alpha sample of galaxies is broadly consistent with this prediction, and suggests that ionizing photons likely escapes from starburst galaxies. The superbubble size distribution also offers a basis for a Simple Inhomogeneous Model for galactic chemical evolution, which is especially relevant to metal-poor systems and instantaneous metallicity distributions. This model offers an alternative interpretation of the Galactic halo metallicity distribution and emphasizes the relative importance of star-formation intensity, in addition to age, in a system's evolution. The fraction of zero-metallicity, Population III stars is easily predicted for any such model. We emphasize that all these phenomena can be modeled in a simple, analytic framework over an extreme range in scale, offering powerful tools for understanding the role of massive stars in the cosmos. (Abridged)

  7. INFRARED AND ULTRAVIOLET STAR FORMATION IN BRIGHTEST CLUSTER GALAXIES IN THE ACCEPT SAMPLE

    SciTech Connect (OSTI)

    Hoffer, Aaron S.; Donahue, Megan; Hicks, Amalia [Physics and Astronomy Department, Michigan State University, East Lansing, MI 48824-2320 (United States); Barthelemy, R. S., E-mail: hofferaa@msu.edu, E-mail: donahue@pa.msu.edu, E-mail: hicksam@msu.edu, E-mail: ramon.s.barthelemy@wmich.edu [Physics Department, Western Michigan University, Kalamazoo, MI 49008-5252 (United States)

    2012-03-01T23:59:59.000Z

    We present infrared (IR) and ultraviolet (UV) photometry for a sample of brightest cluster galaxies (BCGs). The BCGs are from a heterogeneous but uniformly characterized sample, the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT), of X-ray galaxy clusters from the Chandra X-ray telescope archive with published gas temperature, density, and entropy profiles. We use archival Galaxy Evolution Explorer (GALEX), Spitzer Space Telescope, and Two Micron All Sky Survey (2MASS) observations to assemble spectral energy distributions (SEDs) and colors for BCGs. We find that while the SEDs of some BCGs follow the expectation of red, dust-free old stellar populations, many exhibit signatures of recent star formation in the form of excess UV or mid-IR emission, or both. We establish a mean near-UV (NUV) to 2MASS K color of 6.59 {+-} 0.34 for quiescent BCGs. We use this mean color to quantify the UV excess associated with star formation in the active BCGs. We use both fits to a template of an evolved stellar population and library of starburst models and mid-IR star formation relations to estimate the obscured star formation rates (SFRs). We show that many of the BCGs in X-ray clusters with low central gas entropy exhibit enhanced UV (38%) and mid-IR emission (43%) from 8 to 160 {mu}m, above that expected from an old stellar population. These excesses are consistent with ongoing star formation activity in the BCG, star formation that appears to be enabled by the presence of high-density, X-ray-emitting intergalactic gas in the core of the cluster of galaxies. This hot, X-ray-emitting gas may provide the enhanced ambient pressure and some of the fuel to trigger star formation. This result is consistent with previous works that showed that BCGs in clusters with low central gas entropies host H{alpha} emission-line nebulae and radio sources, while clusters with high central gas entropy exhibit none of these features. GALEX UV and Spitzer mid-IR measurements combined provide a complete picture of unobscured and obscured star formation occurring in these systems. We present IR and UV photometry and estimated equivalent continuous SFRs for a sample of BCGs.

  8. A Chemical Study of Varieties of Cotton Seed.

    E-Print Network [OSTI]

    Harrington, M. T. (Marion Thomas)

    1928-01-01T23:59:59.000Z

    . The other data are compiled from the literature. Table 1.-Some characteristics of varieties of cotton. Burnett Group includes : Burnett, B-9-1, Westex. Delfos Group includes: Delfos, Delfos 633, Delfos 1374, Delfoq 610? Lone Star Group includes: Lone... Star, Startex, Lanlihart, Russell. Mebane Group includes: Anton, Blue Wagon, Cliett, Harper, JCasch, Mebane, nfueck, New Boykin. Name BurnettGroup ................................... DelfosGroup .................................... Lone Star Group...

  9. Cotton Variety Experiments at Substation No. 2, Troup.

    E-Print Network [OSTI]

    Hotchkiss, W. S.; Johnson, P. R. (Paul Rufus)

    1930-01-01T23:59:59.000Z

    . ...................... ............................ Lone Star .................... Hawkln's Prolific.. .................. Cleveland Big Boll.. Lone Star ............................. Percentage of lint Results in 1917 No. of bolls per lb. Fifty-three varieties were tested in 1917, and data... Type Mebane or Triumph Truitt Rowden Lone Star Acala Half and Half The varieties tested each year are arranged in the tables according to their rank in yield of lint cotton. Tables 3 to 6, inclusive, give information on the percentage of lint...

  10. Transportation and Greenhouse Gas Mitigation

    E-Print Network [OSTI]

    Lutsey, Nicholas P.; Sperling, Dan

    2008-01-01T23:59:59.000Z

    fuels (eg diesel, compressed natural gas). Electricity (infossil fuels, such as compressed natural gas and liquefied

  11. Compressed gas manifold

    DOE Patents [OSTI]

    Hildebrand, Richard J. (Edgemere, MD); Wozniak, John J. (Columbia, MD)

    2001-01-01T23:59:59.000Z

    A compressed gas storage cell interconnecting manifold including a thermally activated pressure relief device, a manual safety shut-off valve, and a port for connecting the compressed gas storage cells to a motor vehicle power source and to a refueling adapter. The manifold is mechanically and pneumatically connected to a compressed gas storage cell by a bolt including a gas passage therein.

  12. Noble gas magnetic resonator

    DOE Patents [OSTI]

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2014-04-15T23:59:59.000Z

    Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

  13. OIL & GAS INSTITUTE Introduction

    E-Print Network [OSTI]

    Mottram, Nigel

    OIL & GAS INSTITUTE CONTENTS Introduction Asset Integrity Underpinning Capabilities 2 4 4 6 8 9 10 COMPETITIVENESS UNIVERSITY of STRATHCLYDE OIL & GAS INSTITUTE OIL & GAS EXPERTISE AND PARTNERSHIPS #12;1 The launch of the Strathclyde Oil & Gas Institute represents an important step forward for the University

  14. Extraplanar Dust and Star Formation in Nearby Edge-On Galaxies

    E-Print Network [OSTI]

    J. Christopher Howk; Blair D. Savage

    1998-10-27T23:59:59.000Z

    We present high-resolution ( 0.5 - 2.0. If Milky Way gas-to-dust relationships are appropriate, then these structures have gaseous column densities N_H > 10(21) cm(-2), with very large masses (>10(5) - 10(6) solar masses) and gravitational potential energies (> 10(51) - 10(52) ergs relative to z=0). The estimated column densities suggest molecular gas may be present, and with the estimated masses allows for the possibility of star formation in these dusty clouds. Recent star formation is the likely cause of the discrete H II regions, in some cases associated with relatively blue continuum sources, observed at heights 0.6 < |z| < 0.8 kpc above the disks of these galaxies. The presence of early-type stars at high-z in these galaxies may be related to the extraplanar dust structures seen in our images.

  15. Propagation of light in low pressure gas

    E-Print Network [OSTI]

    Jacques Moret-Bailly

    2012-04-13T23:59:59.000Z

    The criticism by W. E. Lamb, W. Schleich, M. Scully, C. Townes of a simplified quantum electrodynamics which represents the photon as a true particle is illustrated. Collisions being absent in low-pressure gas, exchanges of energy are radiative and coherent. Thin shells of plasma containing atoms in a model introduced by Str\\"omgren are superradiant, seen as circles possibly dotted. Spectral radiance of novae has magnitude of laser radiance, and column densities are large in nebulae: Superradiance, multiphoton effects, etc., work in astrophysics. The superradiant beams induce multiphotonic scatterings of light emitted by the stars, brightening the limbs of plasma bubbles and darkening the stars. In excited atomic hydrogen, impulsive Raman scatterings shift frequencies of light. Microwaves exchanged with the Pioneer probes are blueshifted, simulating anomalous accelerations. Substituting coherence for wrong calculations in astrophysical papers, improves results, avoids "new physics".

  16. Axion emission from a magnetized neutron gas

    SciTech Connect (OSTI)

    Skobelev, V. V., E-mail: v.skobelev@inbox.ru [Moscow State Industrial University (Russian Federation)

    2011-01-15T23:59:59.000Z

    By using the polarization density matrix for a neutron in a magnetic field, the axion luminosity of magnetic neutron stars that is associated with the flip of the anomalous magnetic moment of degenerate nonrelativistic neutrons is calculated. It is shown that, at values of the magnetic-field induction in the region B Greater-Than-Or-Equivalent-To 10{sup 18} G, this mechanism of axion emission is dominant in 'young' neutron stars of temperature about a few tens of MeV units. At B {approx} 10{sup 17} G, it is one of the basic mechanisms. The Fermi energy of a degenerate neutron gas in a magnetic field is found, and it is shown that there is no such mechanism of axion emission in the degenerate case.

  17. Phases and Structures of Interstellar Gas

    E-Print Network [OSTI]

    B. Elmegreen

    1999-06-12T23:59:59.000Z

    The thermal and chemical phases of the cool component of interstellar gas are discussed. Variations with galactocentric radius and from galaxy to galaxy are mostly the result of changes in the ambient interstellar pressure and radiation field. Interstellar structure that is hierarchical or fractal in the cloudy parts and has large and connected empty regions between these clouds is probably the result of turbulence. Such structure opens up the disk to the transmission of OB star light into the halo, and it provides for a diffuse ionized component that tapers away gradually from each dense HII region. Fractal cloud structure may also produce the cloud and clump mass functions, and perhaps even the star cluster mass function.

  18. EPA ENERGY STAR: Tackling Growth in Home Electronics and Small Appliances

    E-Print Network [OSTI]

    Sanchez, Marla Christine

    2008-01-01T23:59:59.000Z

    behavior: the case of ENERGY STAR computers Unlike ENERGY STAR ME, participation in ENERGY STAR home

  19. EPA ENERGY STAR Webcast: Value of ENERGY STAR Certification

    Office of Energy Efficiency and Renewable Energy (EERE)

    For thousands of organizations, ENERGY STAR is the simple choice for saving money and demonstrating environmental leadership to the public. Lower energy costs aren't the only financial benefit of...

  20. EPA ENERGY STAR Webinar: ENERGY STAR Portfolio Manager 201

    Office of Energy Efficiency and Renewable Energy (EERE)

    Continue to learn about EPA’s ENERGY STAR Portfolio Manager tool, with a deeper dive into more advanced functionalities such as: managing and tracking changes to your property uses over time; using...

  1. ENERGY STAR Webinar: Financing Energy Efficient Upgrades with ENERGY STAR

    Broader source: Energy.gov [DOE]

    ENERGY STAR is hosting a webinar on how public sector organizations are improving energy efficiency with innovative solutions to financial barriers on Oct. 21, 2014, from 2:00 p.m. - 3:15 p.m.

  2. Star Trek Songbook Issue 3

    E-Print Network [OSTI]

    Multiple Contributors

    1976-01-01T23:59:59.000Z

    lunar flower Is growing, Somewhere beyond the stars... Beyond Antares. There waits my love, a-sleeplng, Where my heart is, where my heart is, Where the great blue crane Its watch is keeping, Somewhere beyond the stars... Beyond Antares. I...'ll be back, though It takes forever. Forever is just a day. Forever is just another journey, Tomorrow a stop along the way. Then let the years go fading, Where my heart is, where my heart Is, For my love eternally Is waiting Somewhere, beyond the stars...

  3. Comments on holographic star and the dual QGP

    E-Print Network [OSTI]

    Piyabut Burikham; Tossaporn Chullaphan

    2014-05-08T23:59:59.000Z

    We study static AdS star in generic dimension. The dependence of the mass limit to the bulk fermion mass is explored. In the bulk conformal limit, the mass limit saturates at a value identical to the mass limit of a radiation star or the AdS space filling with pure radiation. The temperature and entropy of the degenerate AdS star in the bulk conformal limit is zero in contrast to the radiation star. Holographically, the universal mass limit corresponds to the upper limit of the deconfinement temperature in the dual gauge picture. The QGP at this temperature is dual to the large black hole and the heat capacity is positive. When the fermion mass increases, the mass limit falls into the range of the small black holes. We found that even though the small black hole has negative heat capacity, the AdS box allows possibilities that it remains in thermal equilibrium with the radiation as long as the size of the black hole is not smaller than a critical size. Consequently, the dual QGP with negative heat capacity can be produced and remains stable thermodynamically at temperature below a saturation temperature $T_{2}$. The QGP with negative heat capacity produced at higher temperature will still condensate completely into a gas of confined hadron.

  4. FRAGMENTATION AND EVOLUTION OF MOLECULAR CLOUDS. III. THE EFFECT OF DUST AND GAS ENERGETICS

    SciTech Connect (OSTI)

    Martel, Hugo [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, QC, G1V 0A6 (Canada); Urban, Andrea [Sapling Learning, Inc., 2815 Exposition Blvd, Austin, TX 78703 (United States); Evans, Neal J. II [Department of Astronomy, University of Texas, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States)

    2012-09-20T23:59:59.000Z

    Dust and gas energetics are incorporated into a cluster-scale simulation of star formation in order to study the effect of heating and cooling on the star formation process. We build on our previous work by calculating separately the dust and gas temperatures. The dust temperature is set by radiative equilibrium between heating by embedded stars and radiation from dust. The gas temperature is determined using an energy-rate balance algorithm which includes molecular cooling, dust-gas collisional energy transfer, and cosmic-ray ionization. The fragmentation proceeds roughly similarly to simulations in which the gas temperature is set to the dust temperature, but there are differences. The structure of regions around sink particles has properties similar to those of Class 0 objects, but the infall speeds and mass accretion rates are, on average, higher than those seen for regions forming only low-mass stars. The gas and dust temperature have complex distributions not well modeled by approximations that ignore the detailed thermal physics. There is no simple relationship between density and kinetic temperature. In particular, high-density regions have a large range of temperatures, determined by their location relative to heating sources. The total luminosity underestimates the star formation rate at these early stages, before ionizing sources are included, by an order of magnitude. As predicted in our previous work, a larger number of intermediate-mass objects form when improved thermal physics is included, but the resulting initial mass function (IMF) still has too few low-mass stars. However, if we consider recent evidence on core-to-star efficiencies, the match to the IMF is improved.

  5. Natural gas monthly

    SciTech Connect (OSTI)

    NONE

    1998-01-01T23:59:59.000Z

    The Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the Natural Gas Monthly features articles designed to assist readers in using and interpreting natural gas information.

  6. A New Algorithm for Radiative Feedback and its Application to the Formation of Massive Stars

    E-Print Network [OSTI]

    R. G. Edgar; C. J. Clarke

    2002-10-15T23:59:59.000Z

    We have developed a simplified method of treating the radiative acceleration of dusty flows. This method retains the sharp impulse at the dust destruction radius that is a feature of frequency dependent radiative transfer, whilst placing minimal demands on computing resources. As such, it is suitable for inclusion in hydrodynamic codes. We have applied this method to the formation of massive stars in spherical geometry, and find that the fraction of a cloud which can accrete on to the central star is a strong function of the Jeans' Number and density profile of the cloud. Massive star formation is favoured by cold homogeneous conditions, as might result in regions where gas is swept up by some external triggering agent. We find (in contrast to previous authors) that massive star formation does not require a depleted dust mixture, although the use of dust at typical interstellar abundances does reduce the final stellar mass compared to cores formed from a depleted mixture.

  7. A SINFONI view of Galaxy Centers: Morphology and Kinematics of five Nuclear Star Formation Rings

    E-Print Network [OSTI]

    Böker, T; Schinnerer, E; Knapen, J H; Ryder, S

    2007-01-01T23:59:59.000Z

    We present near-infrared (H- and K-band) integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. The data, obtained at the Very Large Telescope with the SINFONI spectrograph, are used to construct maps of various emission lines that reveal the individual star forming regions ("hot spots") delineating the rings. We derive the morphological parameters of the rings, and construct velocity fields of the stars and the emission line gas. We propose a qualitative, but robust, diagnostic for relative hot spot ages based on the intensity ratios of the emission lines Brackett gamma, HeI, and [FeII]. Application of this diagnostic to the data presented here provides tentative support for a scenario in which star formation in the rings is triggered predominantly at two well-defined regions close to, and downstream from, the intersection of dust lanes along the bar with the inner Lindblad resonance.

  8. Gravitational Waves from Relativistic Stars

    E-Print Network [OSTI]

    Yasufumi Kojima

    2000-02-23T23:59:59.000Z

    Stellar pulsations in rotating relativistic stars are reviewed. Slow rotation approximation is applied to solving the Einstein equations. The rotational effects on the non-axisymmetric oscillations are explicitly shown in the polar and axial modes.

  9. Inversion of the star transform

    E-Print Network [OSTI]

    Fan Zhao; John C. Schotland; Vadim A. Markel

    2014-05-06T23:59:59.000Z

    We define the star transform as a generalization of the broken ray transform introduced by us in previous work. The advantages of using the star transform include the possibility to reconstruct the absorption and the scattering coefficients of the medium separately and simultaneously (from the same data) and the possibility to utilize scattered radiation which, in the case of the conventional X-ray tomography, is discarded. In this paper, we derive the star transform from physical principles, discuss its mathematical properties and analyze numerical stability of inversion. In particular, it is shown that stable inversion of the star transform can be obtained only for configurations involving odd number of rays. Several computationally-efficient inversion algorithms are derived and tested numerically.

  10. ENERGY STAR Portfolio Manager 101

    Office of Energy Efficiency and Renewable Energy (EERE)

    Join us as we introduce and demonstrate the core functionality of EPA’s ENERGY STAR Portfolio Manager tool. Attendees will learn how to: navigate Portfolio Manager; add a property and enter details...

  11. The STAR Vertex Position Detector

    E-Print Network [OSTI]

    W. J. Llope; J. Zhou; T. Nussbaum; G. W. Hoffmann; K. Asselta; J. D. Brandenburg; J. Butterworth; T. Camarda; W. Christie; H. J. Crawford; X. Dong; J. Engelage; G. Eppley; F. Geurts; J. Hammond; E. Judd; D. L. McDonald; C. Perkins; L. Ruan; J. Scheblein; J. J. Schambach; R. Soja; K. Xin; C. Yang

    2014-03-26T23:59:59.000Z

    The 2x3 channel pseudo Vertex Position Detector (pVPD) in the STAR experiment at RHIC has been upgraded to a 2x19 channel detector in the same acceptance, called the Vertex Position Detector (VPD). This detector is fully integrated into the STAR trigger system and provides the primary input to the minimum-bias trigger in Au+Au collisions. The information from the detector is used both in the STAR Level-0 trigger and offline to measure the location of the primary collision vertex along the beam pipe and the event "start time" needed by other fast-timing detectors in STAR. The offline timing resolution of single detector channels in full-energy Au+Au collisions is ~100 ps, resulting in a start time resolution of a few tens of picoseconds and a resolution on the primary vertex location of ~1 cm.

  12. ENERGY STAR Portfolio Manager 201

    Office of Energy Efficiency and Renewable Energy (EERE)

    Continue to learn about EPA’s new ENERGY STAR Portfolio Manager tool, with a deeper dive into more advanced functionalities such as: managing and tracking changes to your property uses over time;...

  13. NYSERDA- Energy Star Home Builders

    Broader source: Energy.gov [DOE]

    NYSERDA offers a program to encourage more industry involvement in the building of Energy Star rated Homes. Incentives are available for newly constructed residential dwellings of 3 stories or less...

  14. Wind acceleration in AGB stars: Solid ground and loose ends

    E-Print Network [OSTI]

    Höfner, Susanne

    2015-01-01T23:59:59.000Z

    The winds of cool luminous AGB stars are commonly assumed to be driven by radiative acceleration of dust grains which form in the extended atmospheres produced by pulsation-induced shock waves. The dust particles gain momentum by absorption or scattering of stellar photons, and they drag along the surrounding gas particles through collisions, triggering an outflow. This scenario, here referred to as Pulsation-Enhanced Dust-DRiven Outflow (PEDDRO), has passed a range of critical observational tests as models have developed from empirical and qualitative to increasingly self-consistent and quantitative. A reliable theory of mass loss is an essential piece in the bigger picture of stellar and galactic chemical evolution, and central for determining the contribution of AGB stars to the dust budget of galaxies. In this review, I discuss the current understanding of wind acceleration and indicate areas where further efforts by theorists and observers are needed.

  15. VARIABLE WINDS AND DUST FORMATION IN R CORONAE BOREALIS STARS

    SciTech Connect (OSTI)

    Clayton, Geoffrey C.; Zhang Wanshu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Geballe, T. R., E-mail: gclayton@fenway.phys.lsu.edu, E-mail: wzhan21@lsu.edu, E-mail: tgeballe@gemini.edu [Gemini Observatory, 670 N. A'ohoku Place, Hilo, HI 96720 (United States)

    2013-08-01T23:59:59.000Z

    We have observed P-Cygni and asymmetric, blue-shifted absorption profiles in the He I {lambda}10830 lines of 12 R Coronae Borealis stars over short (1 month) and long (3 yr) timescales to look for variations linked to their dust-formation episodes. In almost all cases, the strengths and terminal velocities of the line vary significantly and are correlated with dust formation events. Strong absorption features with blue-shifted velocities {approx}400 km s{sup -1} appear during declines in visible brightness and persist for about 100 days after recovery to maximum brightness. Small residual winds of somewhat lower velocity are present outside of the decline and recovery periods. The correlations support models in which recently formed dust near the star is propelled outward at high speed by radiation pressure and drags the gas along with it.

  16. STAR Vertex Detector Upgrade Development

    SciTech Connect (OSTI)

    Greiner, Leo C.; Matis, Howard S.; Stezelberger, Thorsten; Vu,Chinh Q.; Wieman, Howard; Szelezniak, Michal; Sun, Xiangming

    2008-01-28T23:59:59.000Z

    We report on the development and prototyping efforts undertaken with the goal of producing a micro-vertex detector for the STAR experiment at the RHIC accelerator at BNL. We present the basic detector requirements and show a sensor development path, conceptual mechanical design candidates and readout architecture. Prototyping and beam test results with current generation MimoSTAR-2 sensors and a readout system featuring FPGA based on-the-fly hit finding and data sparsification are also presented.

  17. FEEDBACK EFFECTS ON LOW-MASS STAR FORMATION

    SciTech Connect (OSTI)

    Hansen, Charles E.; Klein, Richard I.; McKee, Christopher F. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Fisher, Robert T. [Physics Department, University of Massachusetts, Dartmouth, MA (United States)

    2012-03-01T23:59:59.000Z

    Protostellar feedback, both radiation and bipolar outflows, dramatically affects the fragmentation and mass accretion from star-forming cores. We use ORION, an adaptive mesh refinement gravito-radiation-hydrodynamics code, to simulate low-mass star formation in a turbulent molecular cloud in the presence of protostellar feedback. We present results of the first simulations of a star-forming cluster that include both radiative transfer and protostellar outflows. We run four simulations to isolate the individual effects of radiation feedback and outflow feedback as well as the combination of the two. We find that outflows reduce protostellar masses and accretion rates each by a factor of three and therefore reduce protostellar luminosities by an order of magnitude. This means that, while radiation feedback suppresses fragmentation, outflows render protostellar radiation largely irrelevant for low-mass star formation above a mass scale of 0.05 M{sub Sun }. We find initial fragmentation of our cloud at half the global Jeans length, around 0.1 pc. With insufficient protostellar radiation to stop it, these 0.1 pc cores fragment repeatedly, forming typically 10 stars each. The accretion rate in these stars scales with mass as predicted from core accretion models that include both thermal and turbulent motions; the accretion rate does not appear to be consistent with either competitive accretion or accretion from an isothermal sphere. We find that protostellar outflows do not significantly affect the overall cloud dynamics, in the absence of magnetic fields, due to their small opening angles and poor coupling to the dense gas. The outflows reduce the mass from the cores by 2/3, giving a core to star efficiency, {epsilon}{sub core} {approx_equal} 1/3. The simulations are also able to reproduce many observation of local star-forming regions. Our simulation with radiation and outflows reproduces the observed protostellar luminosity function. All of the simulations can reproduce observed core mass functions, though we find they are sensitive to telescope resolution. We also reproduce the two-point correlation function of these observed cores. Lastly, we reproduce the initial mass function itself, including the low-mass end, when outflows are included.

  18. Self-graviting Gas Spheres in Equilibrium State

    E-Print Network [OSTI]

    Andrei Smirnov; Ricardo Max Menezes Oliveira

    2014-11-04T23:59:59.000Z

    In the paper we discuss equilibrium states of stars, using a simplified analytic model. A star is considered as self-graviting body of gas. We use a condition for the equilibrium state of the body in the form of a differential equation, which relates the pressure distribution and mass density in the body. The density distributions of constant, potential, gaussian, and exponential forms are discussed. Exact expressions for the distribution of mass and pressure along the radial direction, and the central pressure were obtained.

  19. Helium in Chemically Peculiar Stars

    E-Print Network [OSTI]

    F. Leone

    1998-05-05T23:59:59.000Z

    For the purpose of deriving the helium abundances in chemically peculiar stars, the importance of assuming a correct helium abundance has been investigated for determining the effective temperature and gravity of main sequence B-type stars, making full use of the present capability of reproducing their helium lines. Even if the flux distribution of main sequence B-type stars appears to depend only on the effective temperature for any helium abundance, the effective temperature, gravity and helium abundance have to be determined simultaneously by matching the Balmer line profiles. New MULTI NLTE calculations, performed adopting ATLAS9 model atmospheres and updated helium atomic parameters, reproduce most of the observed equivalent widths of neutral helium lines for main sequence B-type stars and they make us confident of the possibility to correctly derive the helium abundance in chemically peculiar stars. An application of previous methods to the helium rich star HD 37017 shows that helium could be stratified in the magnetic pole regions, as expected in the framework of the diffusion theory in the presence of mass loss.

  20. Seeding High Redshift QSOs by Collisional Runaway in Primordial Star Clusters

    E-Print Network [OSTI]

    Katz, Harley; Haehnelt, Martin G

    2015-01-01T23:59:59.000Z

    We study how runaway stellar collisions in high redshift, metal poor star clusters form very massive stars (VMSs) that can directly collapse to intermediate mass black holes (IMBHs). We follow the evolution of a pair of two neighboring high-redshift mini-halos which are expected to host central nuclear star clusters (NSCs) with very high resolution, cosmological hydrodynamical zoom-in simulations with the adaptive mesh refinement code RAMSES. One of the two mini-halos enriches the central NSC of the other mini-halo to a critical metallicity, sufficient for Pop. II star formation at redshift z~27. We then use the spatial configuration of the flattened, asymmetrical gas cloud forming in the RAMSES simulations at the core of the metal enriched halo to set the initial conditions for simulations of an initially non-spherical star cluster with the direct summation code NBODY6 which are compared to about 2000 NBODY6 simulations of spherical star clusters for a wide range of star cluster parameters. In this way we es...

  1. Thermodynamics of Ideal Gas in Cosmology

    E-Print Network [OSTI]

    Ying-Qiu Gu

    2009-10-04T23:59:59.000Z

    The equation of state and the state functions for the gravitational source are necessary conditions for solving cosmological model and stellar structure. The usual treatments are directly based on the laws of thermodynamics, and the physical meanings of some concepts are obscure. This letter show that, we can actually derive all explicit fundamental state functions for the ideal gas in the context of cosmology via rigorous dynamical and statistical calculation. These relations have clear physical meanings, and are valid in both non-relativistic and ultra-relativistic cases. Some features of the equation of state are important for a stable structure of a star with huge mass.

  2. RADIATIVE COOLING IMPLEMENTATIONS IN SIMULATIONS OF PRIMORDIAL STAR FORMATION

    SciTech Connect (OSTI)

    Hirano, Shingo [Department of Astronomy, School of Science, University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan)] [Department of Astronomy, School of Science, University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan); Yoshida, Naoki, E-mail: hirano@astron.s.u-tokyo.ac.jp, E-mail: naoki.yoshida@ipmu.jp [Department of Physics, School of Science, University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan)] [Department of Physics, School of Science, University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan)

    2013-01-20T23:59:59.000Z

    We study the thermal evolution of primordial star-forming gas clouds using three-dimensional cosmological simulations. We critically examine how assumptions and approximations made in calculating radiative cooling rates affect the dynamics of the collapsing gas clouds. We consider two important molecular hydrogen cooling processes that operate in a dense primordial gas: H{sub 2} line cooling and continuum cooling by H{sub 2} collision-induced emission. To calculate the optically thick cooling rates, we follow the Sobolev method for the former, whereas we perform ray tracing for the latter. We also run the same set of simulations using simplified fitting functions for the net cooling rates. We compare the simulation results in detail. We show that the time- and direction-dependence of hydrodynamic quantities such as gas temperature and local velocity gradients significantly affects the optically thick cooling rates. Gravitational collapse of the cloud core is accelerated when the cooling rates are calculated by using the fitting functions. The structure and evolution of the central pre-stellar disk are also affected. We conclude that physically motivated implementations of radiative transfer are necessary to follow accurately the thermal and chemical evolution of a primordial gas to high densities.

  3. COMPOSITION OF LOW-REDSHIFT HALO GAS

    SciTech Connect (OSTI)

    Cen Renyue, E-mail: cen@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544 (United States)

    2013-06-20T23:59:59.000Z

    Halo gas in low-z (z < 0.5) {>=}0.1 L{sub *} galaxies in high-resolution, large-scale cosmological hydrodynamic simulations is examined with respect to three components: cold, warm, and hot with temperatures of <10{sup 5}, 10{sup 5-6}, and >10{sup 6} K, respectively. Utilizing O VI {lambda}{lambda}1032, 1038 absorption lines, the warm component is compared to observations, and agreement is found with respect to the galaxy-O VI line correlation, the ratio of the O VI line incidence rate in blue to red galaxies, and the amount of O VI mass in star-forming galaxies. A detailed account of the sources of warm halo gas (stellar feedback heating, gravitational shock heating, and accretion from the intergalactic medium), inflowing and outflowing warm halo gas metallicity disparities, and their dependencies on galaxy types and environment is also presented. With the warm component securely anchored, our simulations make the following additional predictions. First, cold gas is the primary component in inner regions with its mass comprising 50% of all gas within galactocentric radius r = (30, 150) kpc in (red, blue) galaxies. Second, at r > (30, 200) kpc in (red, blue) galaxies the hot component becomes the majority. Third, the warm component is a perpetual minority, with its contribution peaking at {approx}30% at r = 100-300 kpc in blue galaxies and never exceeding 5% in red galaxies. The significant amount of cold gas in low-z early-type galaxies, which was found in simulations and in agreement with recent observations (Thom et al.), is intriguing, as is the dominance of hot gas at large radii in blue galaxies.

  4. Termination of star formation by BH feedback in equal- and unequal-mass mergers of disk and elliptical galaxies

    E-Print Network [OSTI]

    Peter H. Johansson; Thorsten Naab; Andreas Burkert

    2008-09-19T23:59:59.000Z

    We present binary galaxy merger simulations of gas-rich disks (Sp-Sp), of early-type galaxies and disks (E-Sp, mixed mergers), and mergers of early-type galaxies (E-E, dry mergers) with varying mass ratios and different progenitor morphologies. The simulations include radiative cooling, star formation and black hole (BH) accretion and the associated feedback processes. We find for Sp-Sp mergers, that the peak star formation rate and BH accretion rate decrease and the growth timescales of the central black holes and newly formed stars increase with higher progenitor mass ratios. The termination of star formation by BH feedback in disk mergers is significantly less important for higher progenitor mass ratios (e.g. 3:1 and higher). In addition, the inclusion of BH feedback suppresses efficiently star formation in dry E-E mergers and mixed E-Sp mergers.

  5. Chemical Self-Enrichment of HII Regions by the Wolf-Rayet Phase of an 85 Msun star

    E-Print Network [OSTI]

    Danica Kröger; Gerhard Hensler; Tim Freyer

    2006-03-08T23:59:59.000Z

    It is clear from stellar evolution and from observations of WR stars that massive stars are releasing metal-enriched gas through their stellar winds in the Wolf-Rayet phase. Although HII region spectra serve as diagnostics to determine the present-day chemical composition of the interstellar medium, it is far from being understood to what extent the HII gas is already contaminated by chemically processed stellar wind. Therefore, we analyzed our models of radiative and wind bubbles of an isolated 85 Msun star with solar metallicity (Kr\\"oger et al. 2006) with respect to the chemical enrichment of the circumstellar HII region. Plausibly, the hot stellar wind bubble (SWB) is enriched with 14N during the WN phase and even much higher with 12C and 16O during the WC phase of the star. During the short period that the 85 Msun star spends in the WC stage enriched SWB material mixes with warm HII gas of solar abundances and thus enhances the metallicity in the HII region. However, at the end of the stellar lifetime the mass ratios of the traced elements N and O in the warm ionized gas are insignificantly higher than solar, whereas an enrichment of 22 % above solar is found for C. Important issues from the presented study comprise a steeper radial gradient of C than O and a decreasing effect of self-enrichment for metal-poor galaxies.

  6. Cost of Gas Adjustment for Gas Utilities (Maine)

    Broader source: Energy.gov [DOE]

    This rule, applicable to gas utilities, establishes rules for calculation of gas cost adjustments, procedures to be followed in establishing gas cost adjustments and refunds, and describes reports...

  7. Nuclei embedded in an electron gas

    E-Print Network [OSTI]

    Thomas J. Buervenich; Igor N. Mishustin; Walter Greiner

    2007-06-11T23:59:59.000Z

    The properties of nuclei embedded in an electron gas are studied within the relativistic mean-field approach. These studies are relevant for nuclear properties in astrophysical environments such as neutron-star crusts and supernova explosions. The electron gas is treated as a constant background in the Wigner-Seitz cell approximation. We investigate the stability of nuclei with respect to alpha and beta decay. Furthermore, the influence of the electronic background on spontaneous fission of heavy and superheavy nuclei is analyzed. We find that the presence of the electrons leads to stabilizing effects for both $\\alpha$ decay and spontaneous fission for high electron densities. Furthermore, the screening effect shifts the proton dripline to more proton-rich nuclei, and the stability line with respect to beta decay is shifted to more neutron-rich nuclei. Implications for the creation and survival of very heavy nuclear systems are discussed.

  8. Enhanced membrane gas separations

    SciTech Connect (OSTI)

    Prasad, R.

    1993-07-13T23:59:59.000Z

    An improved membrane gas separation process is described comprising: (a) passing a feed gas stream to the non-permeate side of a membrane system adapted for the passage of purge gas on the permeate side thereof, and for the passage of the feed gas stream in a counter current flow pattern relative to the flow of purge gas on the permeate side thereof, said membrane system being capable of selectively permeating a fast permeating component from said feed gas, at a feed gas pressure at or above atmospheric pressure; (b) passing purge gas to the permeate side of the membrane system in counter current flow to the flow of said feed gas stream in order to facilitate carrying away of said fast permeating component from the surface of the membrane and maintaining the driving force for removal of the fast permeating component through the membrane from the feed gas stream, said permeate side of the membrane being maintained at a subatmospheric pressure within the range of from about 0.1 to about 5 psia by vacuum pump means; (c) recovering a product gas stream from the non-permeate side of the membrane; and (d) discharging purge gas and the fast permeating component that has permeated the membrane from the permeate side of the membrane, whereby the vacuum conditions maintained on the permeate side of the membrane by said vacuum pump means enhance the efficiency of the gas separation operation, thereby reducing the overall energy requirements thereof.

  9. Bose-Einstein Condensate general relativistic stars

    E-Print Network [OSTI]

    P. H. Chavanis; T. Harko

    2011-08-19T23:59:59.000Z

    We analyze the possibility that due to their superfluid properties some compact astrophysical objects may contain a significant part of their matter in the form of a Bose-Einstein condensate. To study the condensate we use the Gross-Pitaevskii equation, with arbitrary non-linearity. By introducing the Madelung representation of the wave function, we formulate the dynamics of the system in terms of the continuity equation and of the hydrodynamic Euler equations. The non-relativistic and Newtonian Bose-Einstein gravitational condensate can be described as a gas, whose density and pressure are related by a barotropic equation of state. In the case of a condensate with quartic non-linearity, the equation of state is polytropic with index one. In the framework of the Thomas-Fermi approximation the structure of the Newtonian gravitational condensate is described by the Lane-Emden equation, which can be exactly solved. The case of the rotating condensate is also discussed. General relativistic configurations with quartic non-linearity are studied numerically with both non-relativistic and relativistic equations of state, and the maximum mass of the stable configuration is determined. Condensates with particle masses of the order of two neutron masses (Cooper pair) and scattering length of the order of 10-20 fm have maximum masses of the order of 2 M_sun, maximum central density of the order of 0.1-0.3 10^16 g/cm^3 and minimum radii in the range of 10-20 km. In this way we obtain a large class of stable astrophysical objects, whose basic astrophysical parameters (mass and radius) sensitively depend on the mass of the condensed particle, and on the scattering length. We also propose that the recently observed neutron stars with masses in the range of 2-2.4 M_sun are Bose-Einstein Condensate stars.

  10. Bipolar Outflows and the Evolution of Stars

    E-Print Network [OSTI]

    Adam Frank

    1998-05-20T23:59:59.000Z

    Hypersonic bipolar outflows are a ubiquitous phenomena associated with both young and highly evolved stars. Observations of Planetary Nebulae, the nebulae surrounding Luminous Blue Variables such as $\\eta$ Carinae, Wolf Rayet bubbles, the circumstellar environment of SN 1987A and Young Stellar Objects all revealed high velocity outflows with a wide range of shapes. In this paper I review the current state of our theoretical understanding of these outflows. Beginning with Planetary Nebulae considerable progress has been made in understanding bipolar outflows as the result of stellar winds interacting with the circumstellar environment. In what has been called the "Generalized Wind Blown Bubble" (GWBB) scenario, a fast tenuous wind from the central star expands into a ambient medium with an aspherical (toroidal) density distribution. Inertial gradients due to the gaseous torus quickly lead to an expanding prolate or bipolar shell of swept-up gas bounded by strong shock waves. Numerical simulations of the GWBB scenario show a surprisingly rich variety of gasdynamical behavior, allowing models to recover many of the observed properties of stellar bipolar outflows including the development of collimated supersonic jets. In this paper we review the physics behind the GWBB scenario in detail and consider its strengths and weakness. Alternative models involving MHD processes are also examined. Applications of these models to each of the principle classes of stellar bipolar outflow (YSO, PNe, LBV, SN87A) are then reviewed. Outstanding issues in the study of bipolar outflows are considered as are those questions which arise when the outflows are viewed as a single class of phenomena occuring across the HR diagram.

  11. ENERGY STAR Test Procedures and Verification | Department of...

    Energy Savers [EERE]

    ENERGY STAR ENERGY STAR Test Procedures and Verification ENERGY STAR Test Procedures and Verification The Department of Energy (DOE) is the lead agency in the development and...

  12. ENHANCED ACCRETION RATES OF STARS ON SUPERMASSIVE BLACK HOLES BY STAR-DISK INTERACTIONS IN GALACTIC NUCLEI

    SciTech Connect (OSTI)

    Just, Andreas; Yurin, Denis; Makukov, Maxim; Berczik, Peter; Omarov, Chingis; Spurzem, Rainer [Astronomisches Rechen-Institut, Zentrum fuer Astronomie, Universitaet Heidelberg, Moenchhof-Strasse 12-14, D-69120 Heidelberg (Germany); Vilkoviskij, Emmanuil Y., E-mail: just@ari.uni-heidelberg.de [Fesenkov Astrophysical Institute, Observatory 23, 050020 Almaty (Kazakhstan)

    2012-10-10T23:59:59.000Z

    We investigate the dynamical interaction of a central star cluster surrounding a supermassive black hole (SMBH) and a central accretion disk (AD). The dissipative force acting on stars in the disk leads to an enhanced mass flow toward the SMBH and to an asymmetry in the phase space distribution due to the rotating AD. The AD is considered as a stationary Keplerian rotating disk, which is vertically extended in order to employ a fully self-consistent treatment of stellar dynamics including the dissipative force originating from star-gas ram pressure effects. The stellar system is treated with a direct high-accuracy N-body integration code. A star-by-star representation, desirable in N-body simulations, cannot be extended to real particle numbers yet. Hence, we carefully discuss the scaling behavior of our model with regard to particle number and tidal accretion radius. The main idea is to find a family of models for which the ratio of two-body relaxation time and dissipation time (for kinetic energy of stellar orbits) is constant, which then allows us to extrapolate our results to real parameters of galactic nuclei. Our model is derived from basic physical principles and as such it provides insight into the role of physical processes in galactic nuclei, but it should be regarded as a first step toward more realistic and more comprehensive simulations. Nevertheless, the following conclusions appear to be robust: the star accretion rate onto the AD and subsequently onto the SMBH is enhanced by a significant factor compared to purely stellar dynamical systems neglecting the disk. This process leads to enhanced fueling of central disks in active galactic nuclei (AGNs) and to an enhanced rate of tidal stellar disruptions. Such disruptions may produce electromagnetic counterparts in the form of observable X-ray flares. Our models improve predictions for their rates in quiescent galactic nuclei. We do not yet model direct stellar collisions in the gravitational potential well of the black hole, which could further enhance the growth rate of the black hole. Our models are relevant for quiescent galactic nuclei, because all our mass accretion rates would give rise to luminosities much smaller than the Eddington luminosity. To reach Eddington luminosities, outflows, and feedback as in the most active QSOs, other scenarios are needed, such as gas accretion after galaxy mergers. However, for AGNs close to the Eddington limit, this process may not serve as the dominant accretion process due to the long timescale.

  13. COMPUTATIONAL OPTIMIZATION OF GAS COMPRESSOR ...

    E-Print Network [OSTI]

    2015-02-26T23:59:59.000Z

    Feb 26, 2015 ... When considering cost-optimal operation of gas transport net- works ..... The four most frequently used drive types are gas turbines, gas driven.

  14. Purchased Gas Adjustment Rules (Tennessee)

    Broader source: Energy.gov [DOE]

    The Purchased Gas Adjustment Rules are implemented by the Tennessee Regulatory Authority (Authority). Purchased Gas Adjustment (PGA) Rules are intended to permit the company/LDC (local gas...

  15. Transportation and Greenhouse Gas Mitigation

    E-Print Network [OSTI]

    Lutsey, Nicholas P.; Sperling, Dan

    2008-01-01T23:59:59.000Z

    natural gas and liquefied petroleum gas have continued to make small contributions to transportation,transportation actions include electric power sector actions, eg coal to natural gas

  16. Natural gas annual 1996

    SciTech Connect (OSTI)

    NONE

    1997-09-01T23:59:59.000Z

    This document provides information on the supply and disposition of natural gas to a wide audience. The 1996 data are presented in a sequence that follows natural gas from it`s production to it`s end use.

  17. Recirculating rotary gas compressor

    DOE Patents [OSTI]

    Weinbrecht, J.F.

    1992-02-25T23:59:59.000Z

    A positive displacement, recirculating Roots-type rotary gas compressor is described which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits which return compressed discharge gas to the compressor housing, where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor. 12 figs.

  18. Recirculating rotary gas compressor

    DOE Patents [OSTI]

    Weinbrecht, John F. (601 Oakwood Loop, NE., Albuquerque, NM 87123)

    1992-01-01T23:59:59.000Z

    A positive displacement, recirculating Roots-type rotary gas compressor which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits (24 and 26) which return compressed discharge gas to the compressor housing (14), where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers (10 and 12) and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor.

  19. Gas and Oil (Maryland)

    Broader source: Energy.gov [DOE]

    The Department of the Environment has the authority to enact regulations pertaining to oil and gas production, but it cannot prorate or limit the output of any gas or oil well. A permit from the...

  20. Microminiature gas chromatograph

    DOE Patents [OSTI]

    Yu, Conrad M. (Antioch, CA)

    1996-01-01T23:59:59.000Z

    A microminiature gas chromatograph (.mu.GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode.

  1. Microminiature gas chromatograph

    DOE Patents [OSTI]

    Yu, C.M.

    1996-12-10T23:59:59.000Z

    A microminiature gas chromatograph ({mu}GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode. 7 figs.

  2. Residual gas analysis device

    DOE Patents [OSTI]

    Thornberg, Steven M. (Peralta, NM)

    2012-07-31T23:59:59.000Z

    A system is provided for testing the hermeticity of a package, such as a microelectromechanical systems package containing a sealed gas volume, with a sampling device that has the capability to isolate the package and breach the gas seal connected to a pulse valve that can controllably transmit small volumes down to 2 nanoliters to a gas chamber for analysis using gas chromatography/mass spectroscopy diagnostics.

  3. Natural gas annual 1995

    SciTech Connect (OSTI)

    NONE

    1996-11-01T23:59:59.000Z

    The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1995 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1991 to 1995 for each Census Division and each State. Annual historical data are shown at the national level.

  4. Natural gas annual 1994

    SciTech Connect (OSTI)

    NONE

    1995-11-17T23:59:59.000Z

    The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1994 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1990 to 1994 for each Census Division and each State. Annual historical data are shown at the national level.

  5. Beryllium in turnoff stars of NGC6397: early Galaxy spallation, cosmochronology and cluster formation

    E-Print Network [OSTI]

    L. Pasquini; P. Bonifacio; S. Randich; D. Galli; R. G. Gratton

    2004-07-26T23:59:59.000Z

    We present the first detection of beryllium in two turnoff stars of the old, metal-poor globular cluster NGC 6397. The beryllium lines are clearly detected and we determine a mean beryllium abundance of log(Be/H)=-12.35 +/- 0.2. The beryllium abundance is very similar to that of field stars of similar Fe content. We interpret the beryllium abundance observed as the result of primary spallation of cosmic rays acting on a Galactic scale, showing that beryllium can be used as a powerful cosmochronometer for the first stellar generations. With this method, we estimate that the cluster formed 0.2-0.3 Gyr after the onset of star formation in the Galaxy, in excellent agreement with the age derived from main sequence fitting. From the same spectra we also find low O (noticeably different for the two stars) and high N abundances, suggesting that the original gas was enriched in CNO processed material. Our beryllium results, together with the N, O, and Li abundances, provide insights on the formation of this globular cluster, showing that any CNO processing of the gas must have occurred in the protocluster cloud before the formation of the stars we observe now. We encounter, however, difficulties in giving a fully consistent picture of the cluster formation, able to explain the complex overall abundance pattern.

  6. Old and new neutron stars

    SciTech Connect (OSTI)

    Ruderman, M.

    1984-09-01T23:59:59.000Z

    The youngest known radiopulsar in the rapidly spinning magnetized neutron star which powers the Crab Nebula, the remnant of the historical supernova explosion of 1054 AD. Similar neutron stars are probably born at least every few hundred years, but are less frequent than Galactic supernova explosions. They are initially sources of extreme relativistic electron and/or positron winds (approx.10/sup 38/s/sup -1/ of 10/sup 12/ eV leptons) which greatly decrease as the neutron stars spin down to become mature pulsars. After several million years these neutron stars are no longer observed as radiopulsars, perhaps because of large magnetic field decay. However, a substantial fraction of the 10/sup 8/ old dead pulsars in the Galaxy are the most probable source for the isotropically distributed ..gamma..-ray burst detected several times per week at the earth. Some old neutron stars are spun-up by accretion from companions to be resurrected as rapidly spinning low magnetic field radiopulsars. 52 references, 6 figures, 3 tables.

  7. Understanding the Elusive Dwarf Carbon Star

    E-Print Network [OSTI]

    Paul J. Green

    1996-08-01T23:59:59.000Z

    Most stars in our Galaxy with photospheric C/O>1 (carbon stars) are not giants but dwarfs. The newly-recognized class of dwarf carbon (dC) stars joins the growing family of stars with peculiar abundances that are now recognized as products of mass-transfer binary (MTB) evolution. The dozen examples now known span a wide range of evolutionary histories, ages, and abundances. These stars can already provide some much-needed constraints on the formation of AGB C stars in the disk and spheroid populations, and on the parameters characterizing binary evolution there. A larger sample of dCs, with some bright members, would hasten our progress.

  8. Valve for gas centrifuges

    DOE Patents [OSTI]

    Hahs, C.A.; Rurbage, C.H.

    1982-03-17T23:59:59.000Z

    The invention is pneumatically operated valve assembly for simulatenously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two on the lines so closed. The value assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  9. Gas Cylinders: Proper Management

    E-Print Network [OSTI]

    Boyer, Elizabeth W.

    Compressed Gas Cylinders: Proper Management And Use Published by the Office of Environment, Health;1 Introduction University of California, Berkeley (UC Berkeley) departments that use compressed gas cylinders (MSDS) and your department's Job Safety Analyses (JSAs). Talk to your gas supplier about hands

  10. Static gas expansion cooler

    DOE Patents [OSTI]

    Guzek, J.C.; Lujan, R.A.

    1984-01-01T23:59:59.000Z

    Disclosed is a cooler for television cameras and other temperature sensitive equipment. The cooler uses compressed gas ehich is accelerated to a high velocity by passing it through flow passageways having nozzle portions which expand the gas. This acceleration and expansion causes the gas to undergo a decrease in temperature thereby cooling the cooler body and adjacent temperature sensitive equipment.

  11. Natural Gas Exploration

    E-Print Network [OSTI]

    Boyer, Elizabeth W.

    . Exploration and extraction of natural gas from the Marcellus shale is a potentially valuable economic stimulus for landowners. You might be wondering how the nation's economic situation is affecting the market for naturalNatural Gas Exploration: A Landowners Guide to Financial Management Natural Gas Exploration

  12. Molecular gas and the dynamics of galaxies

    E-Print Network [OSTI]

    F. Combes

    1999-02-01T23:59:59.000Z

    In this review, I discuss some highlights of recent research on molecular gas in galaxies; large-scale CO maps of nearby galaxies are being made, which extend our knowledge on global properties, radial gradients, and spiral structure of the molecular ISM. Very high resolution are provided by the interferometers, that reveal high velocity gradients in galaxy nuclei, and formation of embedded structures, like bars within bars. Observation of the CO and other lines in starburst galaxies have questioned the H2-to-CO conversion factor. Surveys of dwarfs have shown how the conversion factor depends on metallicity. The molecular content is not deficient in galaxy clusters, as is the atomic gas. Galaxy interactions are very effective to enhance gas concentrations and trigger starbursts. Nuclear disks or rings are frequently observed, that concentrate the star formation activity. Since the density of starbursting galaxies is strongly increasing with redshift, the CO lines are a privileged tool to follow evolution of galaxies and observe the ISM dynamics at high redshift: due to the high excitation of the molecular gas, the stronger high-$J$ CO lines are redshifted into the observable band, which facilitates the detection.

  13. ON THE INITIAL MASS FUNCTION OF LOW-METALLICITY STARS: THE IMPORTANCE OF DUST COOLING

    SciTech Connect (OSTI)

    Dopcke, Gustavo [Member of the International Max Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg, IMPRS-HD, Germany. (Germany)] [Member of the International Max Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg, IMPRS-HD, Germany. (Germany); Glover, Simon C. O.; Clark, Paul C.; Klessen, Ralf S., E-mail: gustavo@uni-hd.de [Zentrum fuer Astronomie, Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany)

    2013-04-01T23:59:59.000Z

    The first stars to form in the universe are believed to have distribution of masses biased toward massive stars. This contrasts with the present-day initial mass function, which has a predominance of stars with masses lower than 1 M{sub Sun }. Therefore, the mode of star formation must have changed as the universe evolved. Such a transition is attributed to a more efficient cooling provided by increasing metallicity. Especially dust cooling can overcome the compressional heating, which lowers the gas temperature thus increasing its instability to fragmentation. The purpose of this paper is to verify if dust cooling can efficiently cool the gas, and enhance the fragmentation of gas clouds at the early stages of the universe. To confirm that, we calculate a set of hydrodynamic simulations that include sink particles, which represent contracting protostars. The thermal evolution of the gas during the collapse is followed by making use of a primordial chemical network and also a recipe for dust cooling. We model four clouds with different amounts of metals (10{sup -4}, 10{sup -5}, 10-6 Z{sub Sun }, and 0), and analyze how this property affect the fragmentation of star-forming clouds. We find evidence for fragmentation in all four cases, and hence conclude that there is no critical metallicity below which fragmentation is impossible. Nevertheless, there is a clear change in the behavior of the clouds at Z {approx}< 10{sup -5} Z{sub Sun }, caused by the fact that at this metallicity, fragmentation takes longer to occur than accretion, leading to a flat mass function at lower metallicities.

  14. Welcome FUPWG- Natural Gas Overview

    Broader source: Energy.gov [DOE]

    Presentation—given at the Federal Utility Partnership Working Group (FUPWG) Fall 2008 meeting—provides an overview of natural gas, including emissions, compressed natural gas (CNG) vehicles, and landfill gas supplement for natural gas system.

  15. A WARM MODE OF GAS ACCRETION ON FORMING GALAXIES

    SciTech Connect (OSTI)

    Murante, Giuseppe [Osservatorio di Torino, Strada Osservatorio 20, I-10025, Pino Torinese (Tonga) (Italy); Calabrese, Matteo [Dipartimento di Fisica Generale 'Amedeo Avogadro', Universita degli Studi di Torino, Via P. Giuria 1, I-10125, Torino (Italy); De Lucia, Gabriella [I.N.A.F, Osservatorio di Trieste, Via Tiepolo 11, I- 34131, Trieste (Italy); Monaco, Pierluigi; Borgani, Stefano [Dipartimento di Fisica - Sezione di Astronomia, Universita di Trieste, via Tiepolo 11, I-34131 Trieste (Italy); Dolag, Klaus, E-mail: murante@oato.inaf.it, E-mail: monaco@oats.inaf.it, E-mail: borgani@oats.inaf.it, E-mail: calabrese@oato.inaf.it, E-mail: delucia@oats.inaf.it, E-mail: kdolag@mpa-garching.mpg.de [University Observatory Muenchen, Scheinerstr. 1, 81679, Muenchen (Germany)

    2012-04-20T23:59:59.000Z

    We present results from high-resolution cosmological hydrodynamical simulations of a Milky-Way-sized halo, aimed at studying the effect of feedback on the nature of gas accretion. Simulations include a model of interstellar medium and star formation, in which supernova (SN) explosions provide effective thermal feedback. We distinguish between gas accretion onto the halo, which occurs when gas particles cross the halo virial radius, and gas accretion onto the central galaxy, which takes place when gas particles cross the inner one-tenth of the virial radius. Gas particles can be accreted through three different channels, depending on the maximum temperature value, T{sub max}, reached during the particles' past evolution: a cold channel for T{sub max} < 2.5 Multiplication-Sign 10{sup 5} K, a hot one for T > 10{sup 6} K, and a warm one for intermediate values of T{sub max}. We find that the warm channel is at least as important as the cold one for gas accretion onto the central galaxy. This result is at variance with previous findings that the cold mode dominates gas accretion at high redshift. We ascribe this difference to the different SN feedback scheme implemented in our simulations. While results presented so far in the literature are based on uneffective SN thermal feedback schemes and/or the presence of a kinetic feedback, our simulations include only effective thermal feedback. We argue that observational detections of a warm accretion mode in the high-redshift circumgalactic medium would provide useful constraints on the nature of the feedback that regulates star formation in galaxies.

  16. ISO Observations of Pre-Main Sequence and Vega-type Stars

    E-Print Network [OSTI]

    M. E. van den Ancker

    2000-05-03T23:59:59.000Z

    I present an overview of the results obtained by the Infrared Space Observatory (ISO) on circumstellar material in pre-main sequence (PMS) stars. Results obtained for embedded YSOs, Herbig Ae/Be systems and T Tauri stars are reviewed and their connection to the disks around Vega-type systems is discussed. Although the gas contents of the PMS environment will also be discussed briefly, this review will mainly focus on the composition, mineralogy and evolution of dust in these systems, and the results will be compared to those found in other classes of objects, including solar system comets.

  17. Neutron Star Properties with Hyperons

    E-Print Network [OSTI]

    Whittenbury, D L; Thomas, A W; Tsushima, K; Stone, J R

    2012-01-01T23:59:59.000Z

    In the light of the recent discovery of a neutron star with a mass accurately determined to be almost two solar masses, it has been suggested that hyperons cannot play a role in the equation of state of dense matter in $\\beta$-equilibrium. We re-examine this issue in the most recent development of the quark-meson coupling model. Within a relativistic Hartree-Fock approach and including the full tensor structure at the vector-meson-baryon vertices, we find that not only must hyperons appear in matter at the densities relevant to such a massive star but that the maximum mass predicted is completely consistent with the observation.

  18. Nuclear Physics of Neutron Stars

    E-Print Network [OSTI]

    J. Piekarewicz

    2009-01-28T23:59:59.000Z

    Understanding the equation of state (EOS) of cold nuclear matter, namely, the relation between the pressure and energy density, is a central goal of nuclear physics that cuts across a variety of disciplines. Indeed, the limits of nuclear existence, the collision of heavy ions, the structure of neutron stars, and the dynamics of core-collapse supernova, all depend critically on the equation of state of hadronic matter. In this contribution I will concentrate on the special role that nuclear physics plays in constraining the EOS of cold baryonic matter and its impact on the properties of neutron stars.

  19. The Cooling of Compact Stars

    E-Print Network [OSTI]

    Dany Page; Ulrich Geppert; Fridolin Weber

    2005-08-01T23:59:59.000Z

    The cooling of a compact star depends very sensitively on the state of dense matter at supranuclear densities, which essentially controls the neutrino emission, as well as on the structure of the stellar outer layers which control the photon emission. Open issues concern the hyperon population, the presence of meson condensates, superfluidity and superconductivity, and the transition of confined hadronic matter to quark matter. This paper describes these issues and presents cooling calculations based on a broad collection of equations of state for neutron star matter and strange matter. These results are tested against the body of observed cooling data.

  20. Neutron skins and neutron stars

    SciTech Connect (OSTI)

    Piekarewicz, J. [Department of Physics, Florida State University, Tallahassee, FL 32306-4350 (United States)

    2013-11-07T23:59:59.000Z

    The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ('PREX') at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in {sup 208}Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron beams may impact the physics of neutron stars.

  1. Towards a realistic axion star

    E-Print Network [OSTI]

    J. Barranco; A. Bernal

    2008-08-01T23:59:59.000Z

    In this work we estimate the radius and the mass of a self-gravitating system made of axions. The quantum axion field satisfies the Klein-Gordon equation in a curved space-time and the metric components of this space-time are solutions to the Einstein equations with a source term given by the vacuum expectation value of the energy-momentum operator constructed from the axion field. As a first step towards an axion star we consider the up to the sixth term in the axion potential expansion. We found that axion stars would have masses of the order of asteroids and radius of the order of few centimeters.

  2. Natural gas leak mapper

    DOE Patents [OSTI]

    Reichardt, Thomas A. (Livermore, CA); Luong, Amy Khai (Dublin, CA); Kulp, Thomas J. (Livermore, CA); Devdas, Sanjay (Albany, CA)

    2008-05-20T23:59:59.000Z

    A system is described that is suitable for use in determining the location of leaks of gases having a background concentration. The system is a point-wise backscatter absorption gas measurement system that measures absorption and distance to each point of an image. The absorption measurement provides an indication of the total amount of a gas of interest, and the distance provides an estimate of the background concentration of gas. The distance is measured from the time-of-flight of laser pulse that is generated along with the absorption measurement light. The measurements are formated into an image of the presence of gas in excess of the background. Alternatively, an image of the scene is superimosed on the image of the gas to aid in locating leaks. By further modeling excess gas as a plume having a known concentration profile, the present system provides an estimate of the maximum concentration of the gas of interest.

  3. Revealing a universal planet-metallicity correlation for planets of different solar-type stars

    SciTech Connect (OSTI)

    Wang, Ji; Fischer, Debra A., E-mail: ji.wang@yale.edu [Department of Astronomy, Yale University, New Haven, CT 06511 (United States)

    2015-01-01T23:59:59.000Z

    The metallicity of exoplanet systems serves as a critical diagnostic of planet formation mechanisms. Previous studies have demonstrated the planet–metallicity correlation for large planets (R{sub P} ? 4 R{sub E}); however, a correlation has not been found for smaller planets. With a sample of 406 Kepler objects of interest whose stellar properties are determined spectroscopically, we reveal a universal planet–metallicity correlation: not only gas-giant planets (3.9 R{sub E} gas-dwarf (1.7 R{sub E} stars. The planet occurrence rates of gas-giant planets, gas-dwarf planets, and terrestrial planets are 9.30{sub ?3.04}{sup +5.62}, 2.03{sub ?0.26}{sup +0.29}, and 1.72{sub ?0.17}{sup +0.19} times higher for metal-rich stars than for metal-poor stars, respectively.

  4. Gas Hydrate Storage of Natural Gas

    SciTech Connect (OSTI)

    Rudy Rogers; John Etheridge

    2006-03-31T23:59:59.000Z

    Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a lower heat transfer rate in the internal heat exchanger than was designed. It is believed that the fins on the heat-exchanger tubes did not make proper contact with the tubes transporting the chilled glycol, and pairs of fins were too close for interior areas of fins to serve as hydrate collection sites. A correction of the fabrication fault in the heat exchanger fin attachments could be easily made to provide faster formation rates. The storage success with the POC process provides valuable information for making the process an economically viable process for safe, aboveground natural-gas storage.

  5. Quark stars: their influence on Astroparticle Physics

    E-Print Network [OSTI]

    Sanjay K. Ghosh

    2008-08-12T23:59:59.000Z

    We discuss some of the recent developments in the quark star physics along with the consequences of possible hadron to quark phase transition at high density scenario of neutron stars and their implications on the Astroparticle Physics.

  6. PNM- Energy Star Home Builder Rebate Program

    Broader source: Energy.gov [DOE]

    PNM is offering home builders a rebate for each Energy Star-qualified home they build in PNM service areas. Every Energy Star-qualified home must include effective insulation and air sealing, high...

  7. How to Apply for the ENERGY STAR®

    Broader source: Energy.gov [DOE]

    Join us to learn about applying for ENERGY STAR Certification in Portfolio Manager. Understand the value of the ENERGY STAR certification, see the step-by-step process of applying, and gain tips to...

  8. Equator Appliance: ENERGY STAR Referral (EZ 3720)

    Broader source: Energy.gov [DOE]

    DOE referred Equator Appliance clothes washer EZ 3720 to EPA, brand manager of the ENERGY STAR program, for appropriate action after DOE testing revealed that the model does not meet ENERGY STAR requirements.

  9. Haier: ENERGY STAR Referral (ESA3087)

    Broader source: Energy.gov [DOE]

    DOE referred Haier room air conditioner model ESA3087 to EPA, brand manager of the ENERGY STAR program, for appropriate action after DOE testing revealed that the model does not meet ENERGY STAR requirements.

  10. Simulations of black hole-neutron star binary coalescence

    E-Print Network [OSTI]

    William H. Lee

    2001-01-09T23:59:59.000Z

    We show the results of dynamical simulations of the coalescence of black hole-neutron star binaries. We use a Newtonian Smooth Particle Hydrodynamics code, and include the effects of gravitational radiation back reaction with the quadrupole approximation for point masses, and compute the gravitational radiation waveforms. We assume a polytropic equation of state determines the structure of the neutron star in equilibrium, and use an ideal gas law to follow the dynamical evolution. Three main parameters are explored: (i) The distribution of angular momentum in the system in the initial configuration, namely tidally locked systems vs. irrotational binaries; (ii) The stiffness of the equation of state through the value of the adiabatic index Gamma (ranging from Gamma=5/3 to Gamma=3); (iii) The initial mass ratio q=M(NS)/M(BH). We find that it is the value of Gamma that determines how the coalescence takes place, with immediate and complete tidal disruption for Gamma less than 2, while the core of the neutron star survives and stays in orbit around the black hole for Gamma=3. This result is largely independent of the initial mass ratio and spin configuration, and is reflected directly in the gravitational radiation signal. For a wide range of mass ratios, massive accretion disks are formed (M(disk)~0.2 solar masses), with baryon-free regions that could possibly give rise to gamma ray bursts.

  11. A Star Formation Law for Dwarf Irregular Galaxies

    E-Print Network [OSTI]

    Elmegreen, Bruce G

    2015-01-01T23:59:59.000Z

    The radial profiles of gas, stars, and far ultraviolet radiation in 20 dwarf Irregular galaxies are converted to stability parameters and scale heights for a test of the importance of two-dimensional (2D) instabilities in promoting star formation. A detailed model of this instability involving gaseous and stellar fluids with self-consistent thicknesses and energy dissipation on a perturbation crossing time give the unstable growth rates. We find that all locations are effectively stable to 2D perturbations, mostly because the disks are thick. We then consider the average volume densities in the midplanes, evaluated from the observed HI surface densities and calculated scale heights. The radial profiles of the star formation rates are equal to about 1% of the HI surface densities divided by the free fall times at the average midplane densities. This 1% resembles the efficiency per unit free fall time commonly found in other cases. There is a further variation of this efficiency with radius in all of our galaxi...

  12. TESTING TRIGGERED STAR FORMATION IN SIX H II REGIONS

    SciTech Connect (OSTI)

    Dirienzo, William J.; Indebetouw, Remy [Department of Astronomy, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903 (United States); Brogan, Crystal; Friesen, Rachel K. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Cyganowski, Claudia J. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Churchwell, Ed, E-mail: dirienzo@virginia.edu [Department of Astronomy, University of Wisconsin-Madison, 475 N Charter Street, Madison, WI 53706 (United States)

    2012-12-01T23:59:59.000Z

    We investigated six H II regions with infrared, bright rimmed bubble or cometary morphology, in search of quantitative evidence for triggered star formation, both collect and collapse and radiatively driven implosion (RDI). We identified and classified 458 young stellar objects (YSOs) in and around the H II regions. YSOs were determined by fitting a collection of radiative transfer model spectral energy distributions to infrared photometry for a large sample of point sources. We determined areas where there exist enhanced populations of relatively unevolved YSOs on the bright rims of these regions, suggesting that star formation has been triggered there. We further investigated the physical properties of the regions by using radio continuum emission as a proxy for ionizing flux powering the H II regions, and {sup 13}CO (1-0) observations to measure masses and gravitational stability of molecular clumps. We used an analytical model of collect and collapse triggered star formation, as well as a simulation of RDI, and thus we compare the observed properties of the molecular gas with those predicted in the triggering scenarios. Notably, those regions in our sample that show evidence of cometary, or 'blister', morphology are more likely to show evidence of triggering.

  13. STAR CLUSTER DISRUPTION IN THE STARBURST GALAXY MESSIER 82

    SciTech Connect (OSTI)

    Li, Shuo; Li, Chengyuan [Department of Astronomy, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China); De Grijs, Richard [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China); Anders, Peter, E-mail: grijs@pku.edu.cn [Key Laboratory for Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China)

    2015-01-01T23:59:59.000Z

    Using high-resolution, multiple-passband Hubble Space Telescope images spanning the entire optical/near-infrared wavelength range, we obtained a statistically complete U-band-selected sample of 846 extended star clusters across the disk of the nearby starburst galaxy M82. Based on a careful analysis of the clusters' spectral energy distributions, we determined their galaxy-wide age and mass distributions. The M82 clusters exhibit three clear peaks in their age distribution, thus defining relatively young, log (t yr{sup –1}) ? 7.5, intermediate-age, log (t yr{sup –1}) in [7.5, 8.5], and old samples, log (t yr{sup –1}) ? 8.5. Comparison of the completeness-corrected mass distributions offers a firm handle on the galaxy's star cluster disruption history. The most massive star clusters in the young and old samples are (almost) all concentrated in the most densely populated central region, while the intermediate-age sample's most massive clusters are more spatially dispersed, which may reflect the distribution of the highest-density gas throughout the galaxy's evolutionary history, combined with the solid-body nature of the galaxy's central region.

  14. Black Stars and Gamma Ray Bursts

    E-Print Network [OSTI]

    Tanmay Vachaspati

    2007-06-08T23:59:59.000Z

    Stars that are collapsing toward forming a black hole but are frozen near the Schwarzschild horizon are termed ``black stars''. Collisions of black stars, in contrast to black hole collisions, may be sources of gamma ray bursts, whose basic parameters are estimated quite simply and are found to be consistent with observed gamma ray bursts. Black star gamma ray bursts should be preceded by gravitational wave emission similar to that from the coalescence of black holes.

  15. NuSTAR: Nuclear Spectroscopic Telescope Array

    ScienceCinema (OSTI)

    Craig, Bill

    2014-06-24T23:59:59.000Z

    Bill Craig, an astrophysicist at Lawrence Livermore National Laboratory, describes the NASA NuSTAR mission, launched June 13, 2012.

  16. The nuclear physics of neutron stars

    SciTech Connect (OSTI)

    Piekarewicz, J. [Department of Physics, Florida State University, Tallahassee, FL 32306-4350 (United States)

    2014-05-09T23:59:59.000Z

    We explore the unique and fascinating structure of neutron stars. Although neutron stars are of interest in many areas of Physics, our aim is to provide an intellectual bridge between Nuclear Physics and Astrophysics. We argue against the naive perception of a neutron star as a uniform assembly of neutrons packed to enormous densities. Rather, by focusing on the many exotic phases that are speculated to exist in a neutron star, we show how the reality is different and far more interesting.

  17. Is Her X-1 a strange star?

    E-Print Network [OSTI]

    Jes Madsen

    1996-01-23T23:59:59.000Z

    The possible identification of Her X-1 with a strange star (Li et al. 1995) is shown to be incorrect.

  18. The Nature of the Massive Young Stars in W75 N

    E-Print Network [OSTI]

    D. S. Shepherd; S. E. Kurtz; L. Testi

    2003-10-15T23:59:59.000Z

    We have observed the W75 N massive star forming region in SiO(J=2-1 & J=1-0) at 3" - 5" resolution and in 6 cm, 2 cm, and 7 mm continuum emission at 1.4" - 0.2" resolution. The abundance ratio of [SiO]/[H2] is roughly 5-7 x 10^-11 which is typical for what is expected in the ambient component of molecular clouds with active star formation. The SiO morphology is diffuse and centered on the positions of the ultracompact HII regions - no collimated, neutral jet was discovered. The ionized gas surrounding the protostars have emission measures ranging from 1-15 x 10^6 pc cm^-6, densities from 0.4-5 x 10^4 cm^-3, and derived spectral types of the central ionizing stars ranging from B0.5 to B2. Most of the detected sources have spectral indicies which suggest optically thin to moderately optically thick HII regions produced by a central ionizing star. The spread in ages between the oldest and youngest early-B protostars in the W75 N cluster is 0.1-5 x 10^6 years. This evolutionary timescale for W75 N is consistent with that found for early-B stars born in clusters forming more massive stars (Mstar > 25 Msun).

  19. REVISITING THE FIRST GALAXIES: THE EFFECTS OF POPULATION III STARS ON THEIR HOST GALAXIES

    SciTech Connect (OSTI)

    Muratov, Alexander L.; Gnedin, Oleg Y.; Zemp, Marcel [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Gnedin, Nickolay Y., E-mail: muratov@umich.edu [Particle Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2013-08-01T23:59:59.000Z

    We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the adaptive refinement tree code. Our simulations feature a recently developed model for H{sub 2} formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a recipe for the formation of metal-free Population III (Pop III) stars in galaxy-scale simulations that resolve primordial clouds with sufficiently high density. We base our recipe on the results of prior zoom-in simulations that resolved the protostellar collapse in pre-galactic objects. We find the epoch during which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies that host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 10{sup 8} years after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies with a total mass in excess of 3 Multiplication-Sign 10{sup 6} M{sub Sun} re-accrete most of their baryons and transition to metal-enriched Pop II star formation.

  20. CHEMICAL ANALYSIS OF THE NINTH MAGNITUDE CARBON-ENHANCED METAL-POOR STAR BD+44 Degree-Sign 493

    SciTech Connect (OSTI)

    Ito, Hiroko; Aoki, Wako [Department of Astronomical Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Beers, Timothy C. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Tominaga, Nozomu [Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501 (Japan); Honda, Satoshi [Kwasan Observatory, School of Science, Kyoto University, Kyoto 377-0702 (Japan); Carollo, Daniela, E-mail: aoki.wako@nao.ac.jp, E-mail: beers@noao.edu, E-mail: tominaga@konan-u.ac.jp, E-mail: honda@kwasan.kyoto-u.ac.jp, E-mail: daniela.carollo@mq.edu.au [Department of Physics and Astronomy, Astronomy, Astrophysics and Astrophotonic Research Center, Macquarie University, North Ryde, NSW 2109 (Australia)

    2013-08-10T23:59:59.000Z

    We present detailed chemical abundances for the bright carbon-enhanced metal-poor (CEMP) star BD+44 Degree-Sign 493, previously reported on by Ito et al. Our measurements confirm that BD+44 Degree-Sign 493 is an extremely metal-poor ([Fe/H] =-3.8) subgiant star with excesses of carbon and oxygen. No significant excesses are found for nitrogen and neutron-capture elements (the latter of which place it in the CEMP-no class of stars). Other elements that we measure exhibit abundance patterns that are typical for non-CEMP extremely metal-poor stars. No evidence for variations of radial velocity has been found for this star. These results strongly suggest that the carbon enhancement in BD+44 Degree-Sign 493 is unlikely to have been produced by a companion asymptotic giant-branch star and transferred to the presently observed star, nor by pollution of its natal molecular cloud by rapidly-rotating, massive, mega metal-poor ([Fe/H] < - 6.0) stars. A more likely possibility is that this star formed from gas polluted by the elements produced in a ''faint'' supernova, which underwent mixing and fallback, and only ejected small amounts of elements of metals beyond the lighter elements. The Li abundance of BD+44 Degree-Sign 493 (A(Li) = log (Li/H)+12 =1.0) is lower than the Spite plateau value, as found in other metal-poor subgiants. The upper limit on Be abundance (A(Be) = log (Be/H)+12 < - 1.8) is as low as those found for stars with similarly extremely-low metallicity, indicating that the progenitors of carbon- (and oxygen-) enhanced stars are not significant sources of Be, or that Be is depleted in metal-poor subgiants with effective temperatures of {approx}5400 K.

  1. The Carbon-Rich Gas in the Beta Pictoris Circumstellar Disk

    E-Print Network [OSTI]

    Aki Roberge; Paul D. Feldman; Alycia J. Weinberger; Magali Deleuil; Jean-Claude Bouret

    2006-04-20T23:59:59.000Z

    The edge-on disk surrounding the nearby young star Beta Pictoris is the archetype of the "debris disks", which are composed of dust and gas produced by collisions and evaporation of planetesimals, analogues of Solar System comets and asteroids. These disks provide a window on the formation and early evolution of terrestrial planets. Previous observations of Beta Pic concluded that the disk gas has roughly solar abundances of elements [1], but this poses a problem because such gas should be rapidly blown away from the star, contrary to observations of a stable gas disk in Keplerian rotation [1, 2]. Here we report the detection of singly and doubly ionized carbon (CII, CIII) and neutral atomic oxygen (OI) gas in the Beta Pic disk; measurement of these abundant volatile species permits a much more complete gas inventory. Carbon is extremely overabundant relative to every other measured element. This appears to solve the problem of the stable gas disk, since the carbon overabundance should keep the gas disk in Keplerian rotation [3]. New questions arise, however, since the overabundance may indicate the gas is produced from material more carbon-rich than the expected Solar System analogues.

  2. Polymer quantum effects on compact stars models

    E-Print Network [OSTI]

    Guillermo Chacon-Acosta; Hector Hernandez-Hernandez

    2014-08-05T23:59:59.000Z

    In this work we study a completely degenerated fermion gas at zero temperature within a semiclassical approximation for the Hamiltonian arising in polymer quantum mechanics. Polymer quantum systems are quantum mechanical models quantized in a similar way as in loop quantum gravity that allow the study of the discreteness of space and other features of the loop quantization in a simplified way. We obtain the polymer modified thermodynamical properties noticing that the corresponding Fermi energy is exactly the same as if one directly polymerizes the momentum $p_F$. We also obtain the corresponding expansion of thermodynamical variables for small values of the polymer length scale $\\lambda$. With this results we study a simple model of a compact object where the gravitational collapse is supported by electron degeneracy pressure. We find polymer corrections to the mass of the star. When compared with typical measurements of the mass of white dwarfs we obtain a bound on the polymer length of $\\lambda^2\\lesssim 10^{-26}m^2$.

  3. The Chandrasekhar limit for quark stars

    E-Print Network [OSTI]

    Shibaji Banerjee; Sanjay K. Ghosh; Sibaji Raha

    2000-01-14T23:59:59.000Z

    The Chandrasekhar limit for quark stars is evaluated from simple energy balance relations, as proposed by Landau for white dwarfs or neutron stars. It has been found that the limit for quark stars depends on, in addition to the fundamental constants, the Bag constant.

  4. The apsidal motion in close binary stars

    E-Print Network [OSTI]

    B. V. Vasiliev

    2001-10-10T23:59:59.000Z

    It is usually accepted to consider an apsidal motion in binary stars as a direct confirmation that a substance inside stars is not uniformly distributed. It is shown in this paper that the apsidal motion in binary systems observation data is in a good agreement with an existence of uniform plasma cores inside stars if they consist of hydrogen-deuterium-helium mixture.

  5. Carbon stars in populations of different metallicity

    E-Print Network [OSTI]

    M. A. T. Groenewegen

    1998-11-09T23:59:59.000Z

    Our current knowledge of carbon stars in the Local Group and beyond, is discussed. Although many carbon stars and late M-stars have been identified in external galaxies a coherent understanding in terms of the chemical evolution- and star formation rate-history of a galaxy is still largely lacking. Issues that need to be addressed are: 1) for some of the larger galaxies only a small fraction in area has been surveyed so far, 2) surveys have been conducted using different techniques, and may be incomplete in bolometric magnitude, 3) only for some galaxies is there information about the late M-star population, 4) not all galaxies in the Local Group have been surveyed, 5) only for a sub-set of stars are bolometric magnitudes available. From the existing observations one can derive the following: the formation of carbon stars is both a function of metallicity and star-formation. In galaxies with a similar star-formation rate history, there will be relatively more carbon stars formed in the system with the lower metallicity. On the other hand, the scarcity of AGB type carbon stars in some systems with the lowest metallicity indicates that these galaxies have had a low, if any, star-formation rate history over the last few Gyrs.

  6. Carbon sequestration in natural gas reservoirs: Enhanced gas recovery and natural gas storage

    E-Print Network [OSTI]

    Oldenburg, Curtis M.

    2003-01-01T23:59:59.000Z

    gas reservoirs for carbon sequestration and enhanced gasproduction and carbon sequestration, Society of Petroleumfeasibiilty of carbon sequestration with enhanced gas

  7. Flue gas desulfurization

    DOE Patents [OSTI]

    Im, K.H.; Ahluwalia, R.K.

    1984-05-01T23:59:59.000Z

    The invention involves a combustion process in which combustion gas containing sulfur oxide is directed past a series of heat exchangers to a stack and in which a sodium compound is added to the combustion gas in a temparature zone of above about 1400 K to form Na/sub 2/SO/sub 4/. Preferably, the temperature is above about 1800 K and the sodium compound is present as a vapor to provide a gas-gas reaction to form Na/sub 2/SO/sub 4/ as a liquid. Since liquid Na/sub 2/SO/sub 4/ may cause fouling of heat exchanger surfaces downstream from the combustion zone, the process advantageously includes the step of injecting a cooling gas downstream of the injection of the sodium compound yet upstream of one or more heat exchangers to cool the combustion gas to below about 1150 K and form solid Na/sub 2/SO/sub 4/. The cooling gas is preferably a portion of the combustion gas downstream which may be recycled for cooling. It is further advantageous to utilize an electrostatic precipitator downstream of the heat exchangers to recover the Na/sub 2/SO/sub 4/. It is also advantageous in the process to remove a portion of the combustion gas cleaned in the electrostatic precipitator and recycle that portion upstream to use as the cooling gas. 3 figures.

  8. Maximally incompressible neutron star matter

    E-Print Network [OSTI]

    Timothy S. Olson

    2000-12-07T23:59:59.000Z

    Relativistic kinetic theory, based on the Grad method of moments as developed by Israel and Stewart, is used to model viscous and thermal dissipation in neutron star matter and determine an upper limit on the maximum mass of neutron stars. In the context of kinetic theory, the equation of state must satisfy a set of constraints in order for the equilibrium states of the fluid to be thermodynamically stable and for perturbations from equilibrium to propagate causally via hyperbolic equations. Application of these constraints to neutron star matter restricts the stiffness of the most incompressible equation of state compatible with causality to be softer than the maximally incompressible equation of state that results from requiring the adiabatic sound speed to not exceed the speed of light. Using three equations of state based on experimental nucleon-nucleon scattering data and properties of light nuclei up to twice normal nuclear energy density, and the kinetic theory maximally incompressible equation of state at higher density, an upper limit on the maximum mass of neutron stars averaging 2.64 solar masses is derived.

  9. Boson Stars with Nontrivial Topology

    E-Print Network [OSTI]

    Vladimir Dzhunushaliev; Vladimir Folomeev; Christian Hoffmann; Burkhard Kleihaus; Jutta Kunz

    2014-09-24T23:59:59.000Z

    We construct boson star solutions in the presence of a phantom field, allowing for a nontrivial topology of the solutions. The wormholes residing at the core of the configurations lead to a number of qualitative changes of the boson star solutions. In particular, the typical spiraling dependence of the mass and the particle number on the frequency of the boson stars is lost. Instead, the boson stars with nontrivial topology approach a singular configuration in the limit of vanishing frequency. Depending on the value of the coupling constant, the wormhole geometry changes from a single throat configuration to a double throat configuration, featuring a belly inbetween the two throats. Depending on the mass of the boson field and its self-interaction, the mass and the size of these objects cover many orders of magnitude, making them amenable to various astrophysical observations. A stability analysis reveals, that the unstable mode of the Ellis wormhole is retained in the presence of the bosonic matter. However, the negative eigenvalue can get very close to zero, by tuning the parameters of the self-interaction potential appropriately.

  10. Star Formation in the Multiverse

    E-Print Network [OSTI]

    Raphael Bousso; Stefan Leichenauer

    2008-10-17T23:59:59.000Z

    We develop a simple semi-analytic model of the star formation rate (SFR) as a function of time. We estimate the SFR for a wide range of values of the cosmological constant, spatial curvature, and primordial density contrast. Our model can predict such parameters in the multiverse, if the underlying theory landscape and the cosmological measure are known.

  11. Star Formation and Galaxy Environment

    E-Print Network [OSTI]

    H. K. C. Yee

    2000-04-05T23:59:59.000Z

    The dependence of star formation rate on galaxian environment is a key issue in the understanding of galaxy formation and evolution. However, the study of this subject is complex and observationally challenging. This paper reviews some of the current results, drawing mostly from recent large redshift surveys such the LCRS, the MORPH collaboration, and the CNOC1 and CNOC2 redshift surveys.

  12. Torsional oscillations of strange stars

    E-Print Network [OSTI]

    Massimo Mannarelli

    2014-09-12T23:59:59.000Z

    Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange {\\it collapsed} quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of $10^{45}$ erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.

  13. Narrow He II emission in star-forming galaxies at low metallicity. Stellar wind emission from a population of Very Massive Stars

    E-Print Network [OSTI]

    Gräfener, G

    2015-01-01T23:59:59.000Z

    In a recent study star-forming galaxies with HeII emission at moderate redshifts have been found to occur in two modes, distinguished by the width of their HeII emission lines. Broad HeII emission has been attributed to stellar emission from a population of evolved Wolf-Rayet (WR) stars while narrow HeII emission has been attributed to nebular emission excited by a population of very hot PopIII stars formed in pockets of pristine gas at moderate redshifts. In this work we propose an alternative scenario for the origin of the narrow HeII emission, namely very massive stars (VMS) at low metallicity (Z) which form strong but slow WR-type stellar winds due to their proximity to the Eddington limit. We estimate the expected HeII line fluxes and equivalent widths based on wind models for VMS and population synthesis models, and compare the results with recent observations of star-forming galaxies at moderate redshifts. The observed HeII line strengths and equivalent widths are in line with what is expected for a po...

  14. Gas shielding apparatus

    DOE Patents [OSTI]

    Brandt, D.

    1984-06-05T23:59:59.000Z

    An apparatus for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area.

  15. Condensed Surfaces of Magnetic Neutron Stars, Thermal Surface Emission, and Particle Acceleration Above Pulsar Polar Caps

    E-Print Network [OSTI]

    Zach Medin; Dong Lai

    2008-01-18T23:59:59.000Z

    For sufficiently strong magnetic fields and/or low temperatures, the neutron star surface may be in a condensed state with little gas or plasma above it. Such surface condensation can significantly affect the thermal emission from isolated neutron stars, and may lead to the formation of a charge-depleted acceleration zone ("vacuum gap") in the magnetosphere above the stellar polar cap. Using the latest results on the cohesive property of magnetic condensed matter, we quantitatively determine the conditions for surface condensation and vacuum gap formation in magnetic neutron stars. We find that condensation can occur if the thermal energy kT of the neutron star surface is less than about 8% of its cohesive energy Q_s, and that a vacuum gap can form if the neutron star's rotation axis and magnetic moment point in opposite directions and kT is less than about 4% of Q_s. Thus, vacuum gap accelerators may exist for some neutron stars. Motivated by this result, we also study the physics of pair cascades in the vacuum gap model for photon emission by accelerating electrons and positrons due to both curvature radiation and resonant/nonresonant inverse Compton scattering. Our calculations of the condition of cascade-induced vacuum breakdown and the related pulsar death line/boundary generalize previous works to the superstrong field regime. We find that inverse Compton scatterings do not produce a sufficient number of high energy photons in the gap and thus do not lead to pair cascades for most neutron star parameters. We discuss the implications of our results for the recent observations of neutron star thermal radiation as well as for the detection/non-detection of radio emission from high-B pulsars and magnetars.

  16. Valve for gas centrifuges

    DOE Patents [OSTI]

    Hahs, Charles A. (Oak Ridge, TN); Burbage, Charles H. (Oak Ridge, TN)

    1984-01-01T23:59:59.000Z

    The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  17. Thermodynamics of Chaplygin gas

    E-Print Network [OSTI]

    Yun Soo Myung

    2011-05-11T23:59:59.000Z

    We clarify thermodynamics of the Chaplygin gas by introducing the integrability condition. All thermal quantities are derived as functions of either volume or temperature. Importantly, we find a new general equation of state, describing the Chaplygin gas completely. We confirm that the Chaplygin gas could show a unified picture of dark matter and energy which cools down through the universe expansion without any critical point (phase transition).

  18. Home Safety: Radon Gas 

    E-Print Network [OSTI]

    Shaw, Bryan W.; Denny, Monica L.

    1999-11-12T23:59:59.000Z

    Every home should be tested for radon, an invisible, odorless, radioactive gas that occurs naturally. This publication explains the health risks, testing methods, and mitigation and reduction techniques....

  19. String Gas Baryogenesis

    E-Print Network [OSTI]

    G. L. Alberghi

    2010-02-19T23:59:59.000Z

    We describe a possible realization of the spontaneous baryogenesis mechanism in the context of extra-dimensional string cosmology and specifically in the string gas scenario.

  20. Natural gas annual 1997

    SciTech Connect (OSTI)

    NONE

    1998-10-01T23:59:59.000Z

    The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1997 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1993 to 1997 for each Census Division and each State. Annual historical data are shown at the national level. 27 figs., 109 tabs.

  1. Home Safety: Radon Gas

    E-Print Network [OSTI]

    Shaw, Bryan W.; Denny, Monica L.

    1999-11-12T23:59:59.000Z

    Every home should be tested for radon, an invisible, odorless, radioactive gas that occurs naturally. This publication explains the health risks, testing methods, and mitigation and reduction techniques....

  2. Liquefied Natural Gas (Iowa)

    Broader source: Energy.gov [DOE]

    This document adopts the standards promulgated by the National Fire Protection Association as rules for the transportation, storage, handling, and use of liquefied natural gas. The NFPA standards...

  3. Oil and Gas Outlook

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Gas Outlook For Independent Petroleum Association of America November 13, 2014 | Palm Beach, FL By Adam Sieminski, Administrator U.S. Energy Information Administration Recent...

  4. Oil and Gas (Indiana)

    Broader source: Energy.gov [DOE]

    This division of the Indiana Department of Natural Resources provides information on the regulation of oil and gas exploration, wells and well spacings, drilling, plugging and abandonment, and...

  5. NETL: Oil & Gas

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    that address the unique nature and challenging locations of many of our remaining oil and natural gas accumulations. The National Energy Technology Laboratory's (NETL)...

  6. Reversible Acid Gas Capture

    ScienceCinema (OSTI)

    Dave Heldebrant

    2012-12-31T23:59:59.000Z

    Pacific Northwest National Laboratory scientist David Heldebrant demonstrates how a new process called reversible acid gas capture works to pull carbon dioxide out of power plant emissions.

  7. Natural Gas Rules (Louisiana)

    Broader source: Energy.gov [DOE]

    The Louisiana Department of Natural Resources administers the rules that govern natural gas exploration and extraction in the state. DNR works with the Louisiana Department of Environmental...

  8. Gas venting system

    DOE Patents [OSTI]

    Khan, Amjad; Dreier, Ken Wayne; Moulthrop, Lawrence Clinton; White, Erik James

    2010-06-29T23:59:59.000Z

    A system to vent a moist gas stream is disclosed. The system includes an enclosure and an electrochemical cell disposed within the enclosure, the electrochemical cell productive of the moist gas stream. A first vent is in fluid communication with the electrochemical cell for venting the moist gas stream to an exterior of the enclosure, and a second vent is in fluid communication with an interior of the enclosure and in thermal communication with the first vent for discharging heated air to the exterior of the enclosure. At least a portion of the discharging heated air is for preventing freezing of the moist gas stream within the first vent.

  9. HERSCHEL EXPLOITATION OF LOCAL GALAXY ANDROMEDA (HELGA). III. THE STAR FORMATION LAW IN M31

    SciTech Connect (OSTI)

    Ford, George P.; Gear, Walter K.; Smith, Matthew W. L.; Eales, Steve A.; Gomez, Haley L.; Kirk, Jason [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Baes, Maarten; De Looze, Ilse; Fritz, Jacopo; Gentile, Gianfranco; Gordon, Karl D.; Verstappen, Joris [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent (Belgium); Bendo, George J. [Jodrell Bank Centre for Astrophysics, University of Manchester, Alan Turing Building, Manchester M13 9PL (United Kingdom); Boquien, Mederic; Boselli, Alessandro [Aix Marseille Universite, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Cooray, Asantha R. [Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697-4575 (United States); Lebouteiller, Vianney [Service d'Astrophysique, l'Orme des Merisiers, CEA, Saclay, F-91191 Gif-sur-Yvette (France); O'Halloran, Brian [Astrophysics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Spinoglio, Luigi [INAF, Istituto di Fisica dello Spazio Interplanetario, Via Fosso del Cavaliere 100, Tor Vergata, I-00133 Roma (Italy); Wilson, Christine D. [Department of Physics and Astronomy, ABB-241, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4M1 (Canada)

    2013-05-20T23:59:59.000Z

    We present a detailed study of how the star formation rate (SFR) relates to the interstellar medium (ISM) of M31 at {approx}140 pc scales. The SFR is calculated using the far-ultraviolet and 24 {mu}m emission, corrected for the old stellar population in M31. We find a global value for the SFR of 0.25{sup +0.06}{sub -0.04} M{sub sun} yr{sup -1} and compare this with the SFR found using the total far-infrared luminosity. There is general agreement in regions where young stars dominate the dust heating. Atomic hydrogen (H I) and molecular gas (traced by carbon monoxide, CO) or the dust mass is used to trace the total gas in the ISM. We show that the global surface densities of SFR and gas mass place M31 among a set of low-SFR galaxies in the plot of Kennicutt. The relationship between SFR and gas surface density is tested in six radial annuli across M31, assuming a power law relationship with index, N. The star formation (SF) law using total gas traced by H I and CO gives a global index of N = 2.03 {+-} 0.04, with a significant variation with radius; the highest values are observed in the 10 kpc ring. We suggest that this slope is due to H I turning molecular at {Sigma}{sub Gas} {approx} 10 M{sub Sun} pc{sup -2}. When looking at H{sub 2} regions, we measure a higher mean SFR suggesting a better spatial correlation between H{sub 2} and SF. We find N {approx} 0.6 with consistent results throughout the disk-this is at the low end of values found in previous work and argues against a superlinear SF law on small scales.

  10. Massive stars: their contribution to energy and element budget in chemo-dynamical galaxy evolution

    E-Print Network [OSTI]

    Gerhard Hensler

    2007-09-05T23:59:59.000Z

    Here results of numerical radiation hydrodynamical simulations are presented which explore the energetic impact of massive stars on the interstellar medium. We study the evolution of the ambient gas around isolated massive stars in the mass range between 15 and 85 Msun in order to analyze the formation of structures and further the transfer and deposit of the stellar wind and radiation energy into the circumstellar medium until the stars explode as a supernovae. The derived energy transfer efficiencies are much smaller than analytically estimated and should be inserted into chemo-dynamical evolutionary models of galaxies as appropriate parameter values. As an additional issue the element release in the Wolf-Rayet phases and its detectability have been investigated for comparison with observations.

  11. Nature or nurture? Clues from the distribution of specific star formation rates in SDSS galaxies

    E-Print Network [OSTI]

    Casado, Javier; Gavilán, Marta; Terlevich, Roberto; Terlevich, Elena; Hoyos, Carlos; Díaz, Ángeles I

    2015-01-01T23:59:59.000Z

    This work investigates the main mechanism(s) that regulate the specific star formation rate (SSFR) in nearby galaxies, cross-correlating two proxies of this quantity -- the equivalent width of the \\Ha\\ line and the $(u-r)$ colour -- with other physical properties (mass, metallicity, environment, morphology, and the presence of close companions) in a sample of $\\sim82500$ galaxies extracted from the Sloan Digital Sky Survey (SDSS). The existence of a relatively tight `ageing sequence' in the colour-equivalent width plane favours a scenario where the secular conversion of gas into stars (i.e. `nature') is the main physical driver of the instantaneous SSFR and the gradual transition from a `chemically primitive' (metal-poor and intensely star-forming) state to a `chemically evolved' (metal-rich and passively evolving) system. Nevertheless, environmental factors (i.e. `nurture') are also important. In the field, galaxies may be temporarily affected by discrete `quenching' and `rejuvenation' episodes, but such eve...

  12. Spectrometer for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR): Instrument Technology

    SciTech Connect (OSTI)

    Dunagan, Stephen; Johnson, Roy; Zavaleta, Jhony; Russell, P. B.; Schmid, Beat; Flynn, Connor J.; Redemann, Jens; Shinozuka, Yohei; Livingston, J.; Segal Rozenhaimer, Michal

    2013-08-06T23:59:59.000Z

    The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy, to improve knowledge of atmospheric constituents and their links to air-pollution/climate. Direct beam hyper-spectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. 4STAR measurements will tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and future detector evolution. Technical challenges include compact optical collector design, radiometric dynamic range and stability, and broad spectral coverage. Test results establishing the performance of the instrument against the full range of operational requirements are presented, along with calibration, engineering flight test, and scientific field campaign data and results.

  13. 47 Natural Gas Market Trends NATURAL GAS MARKET TRENDS

    E-Print Network [OSTI]

    47 Natural Gas Market Trends Chapter 5 NATURAL GAS MARKET TRENDS INTRODUCTION Natural gas discusses current natural gas market conditions in California and the rest of North America, followed on the outlook for demand, supply, and price of natural gas for the forecasted 20-year horizon. It also addresses

  14. THE STAR FORMATION HISTORY OF LEO T FROM HUBBLE SPACE TELESCOPE IMAGING

    SciTech Connect (OSTI)

    Weisz, Daniel R.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Williams, Benjamin F. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Zucker, Daniel B. [Department of Physics and Astronomy, Macquarie University, Sydney 2109 (Australia); Dolphin, Andrew E. [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Martin, Nicolas F. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); De Jong, Jelte T. A. [Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 Leiden (Netherlands); Holtzman, Jon A. [Department of Astronomy, New Mexico State University, Box 30001, 1320 Frenger St., Las Cruces, NM 88003 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48109 (United States); Belokurov, Vasily; Evans, N. Wyn, E-mail: dweisz@astro.washington.edu [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2012-04-01T23:59:59.000Z

    We present the star formation history (SFH) of the faintest known star-forming galaxy, Leo T, based on deep imaging taken with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2). The HST/WFPC2 color-magnitude diagram (CMD) of Leo T is exquisitely deep, extending {approx}2 mag below the oldest main-sequence turnoff, permitting excellent constraints on star formation at all ages. We use a maximum likelihood CMD fitting technique to measure the SFH of Leo T assuming three different sets of stellar evolution models: Padova (solar-scaled metallicity) and BaSTI (both solar-scaled and {alpha}-enhanced metallicities). The resulting SFHs are remarkably consistent at all ages, indicating that our derived SFH is robust to the choice of stellar evolution model. From the lifetime SFH of Leo T, we find that 50% of the total stellar mass formed prior to z {approx} 1 (7.6 Gyr ago). Subsequent to this epoch, the SFH of Leo T is roughly constant until the most recent {approx}25 Myr, where the SFH shows an abrupt drop. This decrease could be due to a cessation of star formation or stellar initial mass function sampling effects, but we are unable to distinguish between the two scenarios. Overall, our measured SFH is consistent with previously derived SFHs of Leo T. However, the HST-based solution provides improved age resolution and reduced uncertainties at all epochs. The SFH, baryonic gas fraction, and location of Leo T are unlike any of the other recently discovered faint dwarf galaxies in the Local Group, and instead bear strong resemblance to gas-rich dwarf galaxies (irregular or transition), suggesting that gas-rich dwarf galaxies may share common modes of star formation over a large range of stellar mass ({approx}10{sup 5}-10{sup 9} M{sub Sun }).

  15. Shale gas is natural gas trapped inside

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn'tOriginEducationVideo »UsageSecretary of EnergyFocus Group HSS/UnionGlossary Shale GasShale gas

  16. The First Population II Stars Formed in Externally Enriched Mini-halos

    E-Print Network [OSTI]

    Smith, Britton; O'Shea, Brian; Norman, Michael; Khochfar, Sadegh

    2015-01-01T23:59:59.000Z

    We present a simulation of the formation of the earliest Population II stars, starting from cosmological initial conditions and ending when metals created in the first supernovae are incorporated into a collapsing gas-cloud. This occurs after a supernova blast-wave collides with a nearby mini-halo, inducing further turbulence that efficiently mixes metals into the dense gas in the center of the halo. The gas that first collapses has been enriched to a metallicity of Z ~ 2e-5 Zsun. Due to the extremely low metallicity, collapse proceeds similarly to metal-free gas until dust cooling becomes efficient at high densities, causing the cloud to fragment into a large number of low mass objects. This external enrichment mechanism provides a plausible origin for the most metal-poor stars observed, such as SMSS J031300.36-670839.3, that appear to have formed out of gas enriched by a single supernova. This mechanism operates on shorter timescales than the time for low-mass mini-halos (M < 5e5 Msun) to recover their g...

  17. Si and Fe depletion in Galactic star-forming regions observed by the Spitzer Space Telescope

    E-Print Network [OSTI]

    Yoko Okada; Takashi Onaka; Takashi Miyata; Yoshiko K. Okamoto; Itsuki Sakon; Hiroshi Shibai; Hidenori Takahashi

    2008-04-10T23:59:59.000Z

    We report the results of the mid-infrared spectroscopy of 14 Galactic star-forming regions with the high-resolution modules of the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. We detected [SiII] 35um, [FeII] 26um, and [FeIII] 23um as well as [SIII] 33um and H2 S(0) 28um emission lines. Using the intensity of [NII] 122um or 205um and [OI] 146um or 63um reported by previous observations in four regions, we derived the ionic abundance Si+/N+ and Fe+/N+ in the ionized gas and Si+/O0 and Fe+/O0 in the photodissociation gas. For all the targets, we derived the ionic abundance of Si+/S2+ and Fe2+/S2+ for the ionized gas. Based on photodissociation and HII region models the gas-phase Si and Fe abundance are suggested to be 3-100% and solar abundance, respectively, for the ionized gas and 16-100% and 2-22% of the solar abundance, respectively, for the photodissociation region gas. Since the [FeII] 26um and [FeIII] 23um emissions are weak, the high sensitivity of the IRS enables to derive the gas-phase Fe abundance widely in star-forming regions. The derived gas-phase Si abundance is much larger than that in cool interstellar clouds and that of Fe. The present study indicates that 3-100% of Si atoms and <22% of Fe atoms are included in dust grains which are destroyed easily in HII regions, probably by the UV radiation. We discuss possible mechanisms to account for the observed trend; mantles which are photodesorbed by UV photons, organometallic complexes, or small grains.

  18. The Differences of Star Formation History Between Merging Galaxies and Field Galaxies in the EDR of the SDSS

    E-Print Network [OSTI]

    Z. J. Luo; C. G. Shu; J. S. Huang

    2007-03-14T23:59:59.000Z

    Based on the catalog of merging galaxies in the Early Data Release (EDR) of the Sloan Digital Sky Survey (SDSS), the differences of star formation history between merging galaxies and field galaxies are studied statistically by means of three spectroscopic indicators the 4000-\\r{A} break strength, the Balmer absorption-line index, and the specific star formation rate. It is found that for early-type merging galaxies the interactions will not induce significant enhancement of the star-formation activity because of its stability and lack of cool gas. On the other hand, late-type merging galaxies always in general display more active star formation than field galaxies on different timescales within about 1Gyr. We also conclude that the mean stellar ages of late-type merging galaxies are younger than those of late-type field galaxies.

  19. The Differences of Star Formation History Between Merging Galaxies and Field Galaxies in the EDR of the SDSS

    E-Print Network [OSTI]

    Luo, Z J; Huang, J S

    2007-01-01T23:59:59.000Z

    Based on the catalog of merging galaxies in the Early Data Release (EDR) of the Sloan Digital Sky Survey (SDSS), the differences of star formation history between merging galaxies and field galaxies are studied statistically by means of three spectroscopic indicators the 4000-\\r{A} break strength, the Balmer absorption-line index, and the specific star formation rate. It is found that for early-type merging galaxies the interactions will not induce significant enhancement of the star-formation activity because of its stability and lack of cool gas. On the other hand, late-type merging galaxies always in general display more active star formation than field galaxies on different timescales within about 1Gyr. We also conclude that the mean stellar ages of late-type merging galaxies are younger than those of late-type field galaxies.

  20. The cooling of shock-compressed primordial gas

    E-Print Network [OSTI]

    Jarrett L. Johnson; Volker Bromm

    2005-11-10T23:59:59.000Z

    We find that at redshifts z > 10, HD line cooling allows strongly-shocked primordial gas to cool to the temperature of the cosmic microwave background (CMB). This temperature is the minimum value attainable via radiative cooling. Provided that the abundance of HD, normalized to the total number density, exceeds a critical level of ~ 10^{-8}, the CMB temperature floor is reached in a time which is short compared to the Hubble time. We estimate the characteristic masses of stars formed out of shocked primordial gas in the wake of the first supernovae, and resulting from the mergers of dark matter haloes during hierarchical structure formation to be ~ 10 M_{solar}. In addition, we show that cooling by HD enables the primordial gas in relic H II regions to cool to temperatures considerably lower than those reached via H_2 cooling alone. We confirm that HD cooling is unimportant in cases where the primordial gas does not go through an ionized phase, as in the formation process of the very first stars in z ~ 20 minihaloes of mass ~ 10^{6} M_{solar}.

  1. Towards a Realistic Axion Star

    SciTech Connect (OSTI)

    Barranco, J. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-360, 01000. Mexico D.F. (Mexico); Bernal, A. [Instituto de Fisica de la Universidad de Guanajuato, C.P. 37150, Leon, Guanajuato (Mexico)

    2008-07-02T23:59:59.000Z

    In this work we estimate the radius and the mass of a self-gravitating system made of axions. The quantum axion field satisfies the Klein-Gordon equation in a curved space-time and the metric components of this space-time are solutions to the Einstein equations with a source term given by the vacuum expectation value of the energy-momentum operator constructed from the axion field. As a first step towards an axion star we consider the up to the {phi}{sup 6} term in the axion potential expansion. We found that axion stars would have masses of the order of asteroids ({approx}10{sup -10}M{center_dot}) and radius of the order {approx} few centimeters.

  2. Planet formation around stars of various masses: Hot super-Earths

    E-Print Network [OSTI]

    Grant M. Kennedy; Scott J. Kenyon

    2008-04-15T23:59:59.000Z

    We consider trends resulting from two formation mechanisms for short-period super-Earths: planet-planet scattering and migration. We model scenarios where these planets originate near the snow line in ``cold finger'' circumstellar disks. Low-mass planet-planet scattering excites planets to low periastron orbits only for lower mass stars. With long circularisation times, these planets reside on long-period eccentric orbits. Closer formation regions mean planets that reach short-period orbits by migration are most common around low-mass stars. Above ~1 Solar mass, planets massive enough to migrate to close-in orbits before the gas disk dissipates are above the critical mass for gas giant formation. Thus, there is an upper stellar mass limit for short-period super-Earths that form by migration. If disk masses are distributed as a power law, planet frequency increases with metallicity because most disks have low masses. For disk masses distributed around a relatively high mass, planet frequency decreases with increasing metallicity. As icy planets migrate, they shepherd interior objects toward the star, which grow to ~1 Earth mass. In contrast to icy migrators, surviving shepherded planets are rocky. Upon reaching short-period orbits, planets are subject to evaporation processes. The closest planets may be reduced to rocky or icy cores. Low-mass stars have lower EUV luminosities, so the level of evaporation decreases with decreasing stellar mass.

  3. Evidence of the evolved nature of the B[e] star MWC 137

    SciTech Connect (OSTI)

    Muratore, M. F.; Arias, M. L.; Cidale, L. [Departamento de Espectroscopía Estelar, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, and Instituto de Astrofísica de La Plata, CCT La Plata, CONICET-UNLP, Paseo del Bosque S/N, B1900FWA, La Plata (Argentina); Kraus, M.; Oksala, M. E. [Astronomický ústav, Akademie v?d ?eské Republiky, Fri?ova 298, 251 65 Ond?ejov (Czech Republic); Fernandes, M. Borges [Observatório Nacional, Rua General José Cristino 77, 20921-400 São Cristovão, Rio de Janeiro (Brazil); Liermann, A., E-mail: fmuratore@carina.fcaglp.unlp.edu.ar [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)

    2015-01-01T23:59:59.000Z

    The evolutionary phase of B[e] stars is difficult to establish due to the uncertainties in their fundamental parameters. For instance, possible classifications for the Galactic B[e] star MWC 137 include pre-main-sequence and post-main-sequence phases, with a large range in luminosity. Our goal is to clarify the evolutionary stage of this peculiar object, and to study the CO molecular component of its circumstellar medium. To this purpose, we modeled the CO molecular bands using high-resolution K-band spectra. We find that MWC 137 is surrounded by a detached cool (T=1900±100 K) and dense (N=(3±1)×10{sup 21} cm{sup ?2}) ring of CO gas orbiting the star with a rotational velocity, projected to the line of sight, of 84 ± 2 km s{sup ?1}. We also find that the molecular gas is enriched in the isotope {sup 13}C, excluding the classification of the star as a Herbig Be. The observed isotopic abundance ratio ({sup 12}C/{sup 13}C = 25 ± 2) derived from our modeling is compatible with a proto-planetary nebula, main-sequence, or supergiant evolutionary phase. However, based on some observable characteristics of MWC 137, we propose that the supergiant scenario seems to be the most plausible. Hence, we suggest that MWC 137 could be in an extremely short-lived phase, evolving from a B[e] supergiant to a blue supergiant with a bipolar ring nebula.

  4. Challenges, uncertainties and issues facing gas production from gas hydrate deposits

    E-Print Network [OSTI]

    Moridis, G.J.

    2011-01-01T23:59:59.000Z

    of Gas Price ($/Mscf) for Offshore Gas Hydrate StudyEvaluation of deepwater gas-hydrate systems. The Leadingfor Gas Production from Gas Hydrates Reservoirs. J. Canadian

  5. Oil and Gas Exploration

    E-Print Network [OSTI]

    Tingley, Joseph V.

    , oil and gas, and geothermal activities and accomplishments in Nevada: production statistics Products 23. Sloan dolomite quarry 24. Weiser gypsum quarry Oil Fields 1. Blackburn field 2. North WillowMetals Industrial Minerals Oil and Gas Geothermal Exploration Development Mining Processing Nevada

  6. Illinois Natural Gas Summary

    U.S. Energy Information Administration (EIA) Indexed Site

    Withdrawals NA NA NA NA NA NA 1991-2014 From Gas Wells NA NA NA NA NA NA 1991-2014 From Oil Wells NA NA NA NA NA NA 1991-2014 From Shale Gas Wells NA NA NA NA NA NA 2007-2014...

  7. Montana Natural Gas Summary

    U.S. Energy Information Administration (EIA) Indexed Site

    Withdrawals NA NA NA NA NA NA 1991-2014 From Gas Wells NA NA NA NA NA NA 1991-2014 From Oil Wells NA NA NA NA NA NA 1991-2014 From Shale Gas Wells NA NA NA NA NA NA 2007-2014...

  8. Gas Kick Mechanistic Model

    E-Print Network [OSTI]

    Zubairy, Raheel

    2014-04-18T23:59:59.000Z

    -gain and temperature profile in the annulus. This research focuses on these changes in these parameters to be able to detect the occurrence of gas kick and the circulation of the gas kick out from the well. In this thesis, we have developed a model that incorporates...

  9. Fission gas detection system

    DOE Patents [OSTI]

    Colburn, Richard P. (Pasco, WA)

    1985-01-01T23:59:59.000Z

    A device for collecting fission gas released by a failed fuel rod which device uses a filter to pass coolant but which filter blocks fission gas bubbles which cannot pass through the filter due to the surface tension of the bubble.

  10. Western Europe's future gas supplies

    SciTech Connect (OSTI)

    Kardaun, G.

    1983-05-01T23:59:59.000Z

    Decline in indigenous natural gas production by 2000 will be compensated by imported natural gas and LNG and gas from unconventional sources. Coal gas will furnish about 10 percent of the demand, more natural gas imports will come from North Africa and the USSR and additional LNG will come from West Africa, the Middle East and the Western Hemisphere.

  11. MOLECULAR GAS AND NUCLEAR ACTIVITY IN ULTRALUMINOUS INFRARED GALAXIES WITH DOUBLE NUCLEI

    E-Print Network [OSTI]

    Evans, Aaron S.

    an assumption that the radio and infrared emission arise from supernovae and dust heating by massive starsMOLECULAR GAS AND NUCLEAR ACTIVITY IN ULTRALUMINOUS INFRARED GALAXIES WITH DOUBLE NUCLEI A. S August 2 ABSTRACT High-resolution CO(1 ! 0) observations of five ultraluminous infrared galaxies [ULIGs

  12. Covered Product Category: Residential Whole-Home Gas Tankless Water Heaters

    Broader source: Energy.gov [DOE]

    FEMP provides acquisition guidance across a variety of product categories, including whole-home gas tankless water heaters, which are an ENERGY STAR®-qualified product category. Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.

  13. Gas pump with movable gas pumping panels

    DOE Patents [OSTI]

    Osher, John E. (Alamo, CA)

    1984-01-01T23:59:59.000Z

    Apparatus for pumping gas continuously a plurality of articulated panels of getter material, each of which absorbs gases on one side while another of its sides is simultaneously reactivated in a zone isolated by the panels themselves from a working space being pumped.

  14. Magnetic fields in Neutron Stars

    E-Print Network [OSTI]

    Viganò, Daniele; Miralles, Juan A; Rea, Nanda

    2015-01-01T23:59:59.000Z

    Isolated neutron stars show a diversity in timing and spectral properties, which has historically led to a classification in different sub-classes. The magnetic field plays a key role in many aspects of the neutron star phenomenology: it regulates the braking torque responsible for their timing properties and, for magnetars, it provides the energy budget for the outburst activity and high quiescent luminosities (usually well above the rotational energy budget). We aim at unifying this observational variety by linking the results of the state-of-the-art 2D magneto-thermal simulations with observational data. The comparison between theory and observations allows to place two strong constraints on the physical properties of the inner crust. First, strong electrical currents must circulate in the crust, rather than in the star core. Second, the innermost part of the crust must be highly resistive, which is in principle in agreement with the presence of a novel phase of matter so-called nuclear pasta phase.

  15. Winds of Planet Hosting Stars

    E-Print Network [OSTI]

    Nicholson, B A; Brookshaw, L; Vidotto, A A; Carter, B D; Marsden, S C; Soutter, J; Waite, I A; Horner, J

    2015-01-01T23:59:59.000Z

    The field of exoplanetary science is one of the most rapidly growing areas of astrophysical research. As more planets are discovered around other stars, new techniques have been developed that have allowed astronomers to begin to characterise them. Two of the most important factors in understanding the evolution of these planets, and potentially determining whether they are habitable, are the behaviour of the winds of the host star and the way in which they interact with the planet. The purpose of this project is to reconstruct the magnetic fields of planet hosting stars from spectropolarimetric observations, and to use these magnetic field maps to inform simulations of the stellar winds in those systems using the Block Adaptive Tree Solar-wind Roe Upwind Scheme (BATS-R-US) code. The BATS-R-US code was originally written to investigate the behaviour of the Solar wind, and so has been altered to be used in the context of other stellar systems. These simulations will give information about the velocity, pressur...

  16. Shale gas production: potential versus actual greenhouse gas emissions

    E-Print Network [OSTI]

    O’Sullivan, Francis Martin

    Estimates of greenhouse gas (GHG) emissions from shale gas production and use are controversial. Here we assess the level of GHG emissions from shale gas well hydraulic fracturing operations in the United States during ...

  17. Intermountain Gas Company (IGC)- Gas Heating Rebate Program

    Broader source: Energy.gov [DOE]

    The Intermountain Gas Company's (IGC) Gas Heating Rebate Program offers customers a $200 per unit rebate when they convert to a high efficiency natural gas furnace that replaces a heating system...

  18. Peoples Gas and North Shore Gas- Bonus Rebate Program (Illinois)

    Broader source: Energy.gov [DOE]

    The Peoples Gas and North Shore Gas Natural Gas Savings Programs are offering the following bonus rebates (in addition to the joint utilities bonus rebate). For both offers below, installation must...

  19. Underground Storage of Natural Gas and Liquefied Petroleum Gas (Nebraska)

    Broader source: Energy.gov [DOE]

    This statute declares underground storage of natural gas and liquefied petroleum gas to be in the public interest if it promotes the conservation of natural gas and permits the accumulation of...

  20. EIA - Natural Gas Pipeline Network - Natural Gas Supply Basins...

    U.S. Energy Information Administration (EIA) Indexed Site

    Corridors About U.S. Natural Gas Pipelines - Transporting Natural Gas based on data through 20072008 with selected updates U.S. Natural Gas Supply Basins Relative to Major Natural...

  1. Supersonic gas compressor

    DOE Patents [OSTI]

    Lawlor, Shawn P. (Bellevue, WA); Novaresi, Mark A. (San Diego, CA); Cornelius, Charles C. (Kirkland, WA)

    2007-11-13T23:59:59.000Z

    A gas compressor based on the use of a driven rotor having a compression ramp traveling at a local supersonic inlet velocity (based on the combination of inlet gas velocity and tangential speed of the ramp) which compresses inlet gas against a stationary sidewall. In using this method to compress inlet gas, the supersonic compressor efficiently achieves high compression ratios while utilizing a compact, stabilized gasdynamic flow path. Operated at supersonic speeds, the inlet stabilizes an oblique/normal shock system in the gasdyanamic flow path formed between the rim of the rotor, the strakes, and a stationary external housing. Part load efficiency is enhanced by the use of a pre-swirl compressor, and using a bypass stream to bleed a portion of the intermediate pressure gas after passing through the pre-swirl compressor back to the inlet of the pre-swirl compressor. Inlet guide vanes to the compression ramp enhance overall efficiency.

  2. Cryogenic treatment of gas

    DOE Patents [OSTI]

    Bravo, Jose Luis (Houston, TX); Harvey, III, Albert Destrehan (Kingwood, TX); Vinegar, Harold J. (Bellaire, TX)

    2012-04-03T23:59:59.000Z

    Systems and methods of treating a gas stream are described. A method of treating a gas stream includes cryogenically separating a first gas stream to form a second gas stream and a third stream. The third stream is cryogenically contacted with a carbon dioxide stream to form a fourth and fifth stream. A majority of the second gas stream includes methane and/or molecular hydrogen. A majority of the third stream includes one or more carbon oxides, hydrocarbons having a carbon number of at least 2, one or more sulfur compounds, or mixtures thereof. A majority of the fourth stream includes one or more of the carbon oxides and hydrocarbons having a carbon number of at least 2. A majority of the fifth stream includes hydrocarbons having a carbon number of at least 3 and one or more of the sulfur compounds.

  3. Search for bright stars with infrared excess

    SciTech Connect (OSTI)

    Raharto, Moedji, E-mail: moedji@as.itb.ac.id [Astronomy Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2014-03-24T23:59:59.000Z

    Bright stars, stars with visual magnitude smaller than 6.5, can be studied using small telescope. In general, if stars are assumed as black body radiator, then the color in infrared (IR) region is usually equal to zero. Infrared data from IRAS observations at 12 and 25?m (micron) with good flux quality are used to search for bright stars (from Bright Stars Catalogues) with infrared excess. In magnitude scale, stars with IR excess is defined as stars with IR color m{sub 12}?m{sub 25}>0; where m{sub 12}?m{sub 25}?=??2.5log(F{sub 12}/F{sub 25})+1.56, where F{sub 12} and F{sub 25} are flux density in Jansky at 12 and 25?m, respectively. Stars with similar spectral type are expected to have similar color. The existence of infrared excess in the same spectral type indicates the existence of circum-stellar dust, the origin of which is probably due to the remnant of pre main-sequence evolution during star formation or post AGB evolution or due to physical process such as the rotation of those stars.

  4. Gas Storage Technology Consortium

    SciTech Connect (OSTI)

    Joel Morrison

    2005-09-14T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of April 1, 2005 through June 30, 2005. During this time period efforts were directed toward (1) GSTC administration changes, (2) participating in the American Gas Association Operations Conference and Biennial Exhibition, (3) issuing a Request for Proposals (RFP) for proposal solicitation for funding, and (4) organizing the proposal selection meeting.

  5. Evolution of Super Star Cluster Winds with Strong Cooling

    E-Print Network [OSTI]

    Wunsch, Richard; Palous, Jan; Tenorio-Tagle, Guillermo; Munoz-Tunon, Casiana

    2011-01-01T23:59:59.000Z

    We study the evolution of Super Star Cluster (SSC) winds driven by stellar winds and supernova (SN) explosions. Time-dependent rates at which mass and energy are deposited into the cluster volume, as well as the time-dependent chemical composition of the re-inserted gas, are obtained from the population synthesis code Starburst99. These results are used as input for a semi-analytic code which determines the hydrodynamic properties of the cluster wind as a function of cluster age. Two types of winds are detected in the calculations. For the quasi-adiabatic solution, all of the inserted gas leaves the cluster in the form of a stationary wind. For the bimodal solution, some of the inserted gas becomes thermally unstable and forms dense warm clumps which accumulate inside the cluster. We calculate the evolution of the wind velocity and energy flux and integrate the amount of accumulated mass for clusters of different mass, radius and initial metallicity. We consider also conditions with low heating efficiency of ...

  6. Questar Gas- Home Builder Gas Appliance Rebate Program

    Broader source: Energy.gov [DOE]

    Questar Gas provides incentives for home builders to construct energy efficient homes. Rebates are provided for energy efficient gas equipment. Builders can also receive whole house rebates for...

  7. Questar Gas- Home Builder Gas Appliance Rebate Program (Idaho)

    Broader source: Energy.gov [DOE]

    Questar Gas provides incentives for home builders who incorporate energy efficiency into new construction. Rebates are provided for energy efficient gas equipment placed into new construction....

  8. Questar Gas- Home Builder Gas Appliance Rebate Program

    Broader source: Energy.gov [DOE]

    Questar Gas provides incentives for home builders who incorporate energy efficiency into new construction. Rebates are provided for energy efficient gas equipment placed into new construction. ...

  9. ,"New York Natural Gas Gross Withdrawals from Shale Gas (Million...

    U.S. Energy Information Administration (EIA) Indexed Site

    ,,"(202) 586-8800",,,"2262015 9:43:21 AM" "Back to Contents","Data 1: New York Natural Gas Gross Withdrawals from Shale Gas (Million Cubic Feet)"...

  10. natural gas+ condensing flue gas heat recovery+ water creation...

    Open Energy Info (EERE)

    natural gas+ condensing flue gas heat recovery+ water creation+ CO2 reduction+ cool exhaust gases+ Energy efficiency+ commercial building energy efficiency+ industrial energy...

  11. EIA - Natural Gas Pipeline Network - Largest Natural Gas Pipeline...

    U.S. Energy Information Administration (EIA) Indexed Site

    Interstate Pipelines Table About U.S. Natural Gas Pipelines - Transporting Natural Gas based on data through 20072008 with selected updates Thirty Largest U.S. Interstate Natural...

  12. Oil and Gas CDT Using noble gas isotopes to develop a mechanistic understanding of shale gas

    E-Print Network [OSTI]

    Henderson, Gideon

    Oil and Gas CDT Using noble gas isotopes to develop a mechanistic understanding of shale gas, desorbtion, tracing, migration Overview The discovery of shale gas in UK Shales demonstrates how important and no doubt will vary from shale to shale. An improved understanding of the controls on gas production from

  13. Oil and Gas Program (Tennessee)

    Broader source: Energy.gov [DOE]

    The Oil and Gas section of the Tennessee Code, found in Title 60, covers all regulations, licenses, permits, and laws related to the production of natural gas. The laws create the Oil and Gas...

  14. Oil and Gas Production (Missouri)

    Broader source: Energy.gov [DOE]

    A State Oil and Gas Council regulates and oversees oil and gas production in Missouri, and conducts a biennial review of relevant rules and regulations. The waste of oil and gas is prohibited. This...

  15. Co-evolution of nuclear star clusters, massive black holes and their host galaxies

    E-Print Network [OSTI]

    Antonini, Fabio; Silk, Joseph

    2015-01-01T23:59:59.000Z

    Studying how nuclear star clusters (NSCs) form and how they are related to the growth of the central massive black holes (MBHs) and their host galaxies is fundamental for our understanding of the evolution of galaxies and the processes that have shaped their central structures. We present the results of a semi-analytical galaxy formation model that follows the evolution of dark matter halos along merger trees, as well as that of the baryonic components. This model allows us to study the evolution of NSCs in a cosmological context, by taking into account the growth of NSCs due to both dynamical friction-driven migration of stellar clusters and star formation triggered by infalling gas, while also accounting for dynamical heating from (binary) MBHs. We find that in-situ star formation contributes a significant fraction (up to ~40%) of the total mass of NSCs in our model. Both NSC growth through in-situ star formation and through star cluster migration are found to generate NSC -- host galaxy scaling correlation...

  16. Sequentially Triggered Star Formation in OB Associations

    E-Print Network [OSTI]

    Thomas Preibisch; Hans Zinnecker

    2006-10-27T23:59:59.000Z

    We discuss observational evidence for sequential and triggered star formation in OB associations. We first review the star formation process in the Scorpius-Centaurus OB association, the nearest OB association to the Sun, where several recent extensive studies have allowed us to reconstruct the star formation history in a rather detailed way. We then compare the observational results with those obtained for other OB associations and with recent models of rapid cloud and star formation in the turbulent interstellar medium. We conclude that the formation of whole OB subgroups (each consisting of several thousand stars) requires large-scale triggering mechanisms such as shocks from expanding wind and supernova driven superbubbles surrounding older subgroups. Other triggering mechanisms, like radiatively driven implosion of globules, also operate, but seem to be secondary processes, forming only small stellar groups rather than whole OB subgroups with thousands of stars.

  17. Radio Triggered Star Formation in Cooling Flows

    E-Print Network [OSTI]

    B. R. McNamara

    1999-11-08T23:59:59.000Z

    The giant galaxies located at the centers of cluster cooling flows are frequently sites of vigorous star formation. In some instances, star formation appears to have been triggered by the galaxy's radio source. The colors and spectral indices of the young populations are generally consistent with short duration bursts or continuous star formation for durations much less than 1 Gyr, which is less than the presumed ages of cooling flows. The star formation properties are inconsistent with fueling by a continuously accreting cooling flow, although the prevalence of star formation is consistent with repeated bursts and periodic refueling. Star formation may be fueled, in some cases, by cold material stripped from neighboring cluster galaxies.

  18. Exhaust gas recirculation apparatus

    SciTech Connect (OSTI)

    Egnell, R.A.; Hansson, B.L.

    1981-07-14T23:59:59.000Z

    Apparatus is disclosed for recirculating combustion exhaust gases to the burner region of a Stirling cycle hot-gas engine to lower combustion temperature and reduct NO/sub x/ formation includes a first wall separating the exhaust gas stream from the inlet air stream, a second wall separating the exhaust gas stream from the burner region, and low flow resistance ejectors formed in the first and second walls for admitting the inlet air to the burner region and for entraining and mixing with the inlet air portion of the exhaust gas stream. In a preferred embodiment the ejectors are arranged around the periphery of a cylindrical burner region and oriented to admit the air/exhaust gas mixture tangentially to promote mixing. In another preferred embodiment a single annular ejector surrounds and feeds the air/exhaust gas mixture to a cylindrical burner region. The annular ejector includes an annular plate with radially-directed flow passages to provide an even distribution of the air/exhaust gas mixture to the burner region.

  19. Gas Storage Technology Consortium

    SciTech Connect (OSTI)

    Joel L. Morrison; Sharon L. Elder

    2006-07-06T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission & distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of April 1 to June 30, 2006. Key activities during this time period include: (1) Develop and process subcontract agreements for the eight projects selected for cofunding at the February 2006 GSTC Meeting; (2) Compiling and distributing the three 2004 project final reports to the GSTC Full members; (3) Develop template, compile listserv, and draft first GSTC Insider online newsletter; (4) Continue membership recruitment; (5) Identify projects and finalize agenda for the fall GSTC/AGA Underground Storage Committee Technology Transfer Workshop in San Francisco, CA; and (6) Identify projects and prepare draft agenda for the fall GSTC Technology Transfer Workshop in Pittsburgh, PA.

  20. Gas Storage Technology Consortium

    SciTech Connect (OSTI)

    Joel L. Morrison; Sharon L. Elder

    2007-06-30T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is crucial in meeting the needs of these new markets. To address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance the operational flexibility and deliverability of the nation's gas storage system, and provide a cost-effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of April 1, 2007 through June 30, 2007. Key activities during this time period included: (1) Organizing and hosting the 2007 GSTC Spring Meeting; (2) Identifying the 2007 GSTC projects, issuing award or declination letters, and begin drafting subcontracts; (3) 2007 project mentoring teams identified; (4) New NETL Project Manager; (5) Preliminary planning for the 2007 GSTC Fall Meeting; (6) Collecting and compiling the 2005 GSTC project final reports; and (7) Outreach and communications.

  1. Gas Storage Technology Consortium

    SciTech Connect (OSTI)

    Joel L. Morrison; Sharon L. Elder

    2006-05-10T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of January 1, 2006 through March 31, 2006. Activities during this time period were: (1) Organize and host the 2006 Spring Meeting in San Diego, CA on February 21-22, 2006; (2) Award 8 projects for co-funding by GSTC for 2006; (3) New members recruitment; and (4) Improving communications.

  2. Gas Storage Technology Consortium

    SciTech Connect (OSTI)

    Joel L. Morrison; Sharon L. Elder

    2007-03-31T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is crucial in meeting the needs of these new markets. To address the gas storage needs of the natural gas industry, an industry-driven consortium was created - the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance the operational flexibility and deliverability of the nation's gas storage system, and provide a cost-effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of January1, 2007 through March 31, 2007. Key activities during this time period included: {lg_bullet} Drafting and distributing the 2007 RFP; {lg_bullet} Identifying and securing a meeting site for the GSTC 2007 Spring Proposal Meeting; {lg_bullet} Scheduling and participating in two (2) project mentoring conference calls; {lg_bullet} Conducting elections for four Executive Council seats; {lg_bullet} Collecting and compiling the 2005 GSTC Final Project Reports; and {lg_bullet} Outreach and communications.

  3. Galactosynthesis: Halo Histories, Star Formation, and Disks

    E-Print Network [OSTI]

    Ari Buchalter; Raul Jimenez; Marc Kamionkowski

    2000-06-01T23:59:59.000Z

    We investigate the effects of a variety of ingredients that must enter into a realistic model for disk-galaxy formation, focusing primarily on the Tully-Fisher (TF) relation and its scatter in several wavebands. Our main findings are: (a) the slope, normalization, and scatter of the TF relation across various wavebands is determined {\\em both} by halo properties and star formation in the disk; (b) TF scatter owes primarily to the spread in formation redshifts. The scatter can be measurably reduced by chemical evolution, and also in some cases by the weak anti-correlation between peak height and spin; (c) multi-wavelength constraints can be important in distinguishing between models which appear to fit the TF relation in I or K; (d) successful models seem to require that the bulk of disk formation cannot occur too early (z>2) or too late (z<0.5), and are inconsistent with high values of $\\Omega_0$; (e) a realistic model with the above ingredients can reasonably reproduce the observed z=0 TF relation in {\\em all} bands (B, R, I, and K). It can also account for the z=1 B-band TF relation and yield rough agreement with the local B and K luminosity functions and B-band surface-brightness--magnitude relation. The remarkable agreement with observations suggests that the amount of gas that is expelled or poured into a disk galaxy must be small, and that the specific angular momentum of the baryons must roughly equal that of the halo; there is little room for angular momentum transfer. In an appendix we present analytic fits to stellar-population synthesis models.

  4. Differences in the Cooling Behavior of Strange Quark Matter Stars and Neutron Stars

    E-Print Network [OSTI]

    Christoph Schaab; Bernd Hermann; Fridolin Weber; Manfred K. Weigel

    1997-02-21T23:59:59.000Z

    The general statement that hypothetical strange (quark matter) stars cool more rapidly than neutron stars is investigated in greater detail. It is found that the direct Urca process could be forbidden not only in neutron stars but also in strange stars. In this case, strange stars are slowly cooling, and their surface temperatures are more or less indistinguishable from those of slowly cooling neutron stars. Furthermore the case of enhanced cooling is reinvestigated. It shows that strange stars cool significantly more rapidly than neutron stars within the first $\\sim 30$ years after birth. This feature could become particularly interesting if continued observation of SN 1987A would reveal the temperature of the possibly existing pulsar at its center.

  5. Parent Stars of Extrasolar Planets. XV. Host Star Rotation Revisited with {\\it Kepler} Data

    E-Print Network [OSTI]

    Gonzalez, Guillermo

    2015-01-01T23:59:59.000Z

    We employed published rotation periods of {\\it Kepler} field stars to test whether stars hosting planets tend to rotate more slowly than stars without known planets. Spectroscopic vsini observations of nearby stars with planets have indicated that they tend to have smaller visni values. We employ data for {\\it Kepler} Objects of Interest (KOIs) from the first 16 quarters of its original mission; stellar parameters are based on the analysis of the first 17 quarters. We confirm that KOI stars rotate more slowly with much greater confidence than we had previously found for nearby stars with planets. Furthermore, we find that stars with planets of all types rotate more slowly, not just stars with giant planets.

  6. EPA ENERGY STAR Webinar: How to Apply for the ENERGY STAR Certification

    Broader source: Energy.gov [DOE]

    Join us to learn about applying for ENERGY STAR Certification in Portfolio Manager. Understand the value of the ENERGY STAR certification, see the step-by-step process of applying, and gain tips to...

  7. IS THE POST-AGB STAR SAO 40039 MILDLY HYDROGEN-DEFICIENT?

    SciTech Connect (OSTI)

    Rao, S. Sumangala; Pandey, Gajendra; Giridhar, Sunetra [Indian Institute of Astrophysics, Bengaluru-560034 (India); Lambert, David L., E-mail: sumangala@iiap.res.in, E-mail: pandey@iiap.res.in, E-mail: giridhar@iiap.res.in, E-mail: dll@astro.as.utexas.edu [W. J. McDonald Observatory, University of Texas, Austin, TX 78712 (United States)

    2011-08-10T23:59:59.000Z

    We have conducted an LTE abundance analysis for SAO 40039, a warm post-AGB star whose spectrum is known to show surprisingly strong He I lines for its effective temperature and has been suspected of being H-deficient and He-rich. High-resolution optical spectra are analyzed using a family of model atmospheres with different He/H ratios. Atmospheric parameters are estimated from the ionization equilibrium set by neutral and singly ionized species of Fe and Mg, the excitation of Fe I and Fe II lines, and the wings of the Paschen lines. On the assumption that the He I lines are of photospheric and not chromospheric origin, a He/H ratio of approximately unity is found by imposing the condition that the adopted He/H ratio of the model atmosphere must equal the ratio derived from the observed He I triplet lines at 5876, 4471, and 4713 A, and singlet lines at 4922 and 5015 A. Using the model with the best-fitting atmospheric parameters for this He/H ratio, SAO 40039 is confirmed to exhibit mild dust-gas depletion, i.e., the star has an atmosphere deficient in elements of high condensation temperature. The star appears to be moderately metal-deficient with [Fe/H] = -0.4 dex. But the star's intrinsic metallicity as estimated from Na, S, and Zn, elements of a low condensation temperature, is [Fe/H]{sub o} {approx_equal} -0.2 ([Fe/H]{sub o} refers to the star's intrinsic metallicity). The star is enriched in N and perhaps O as well, changes reflecting the star's AGB past and the event that led to He enrichment.

  8. From nuclear matter to Neutron Stars

    E-Print Network [OSTI]

    T. K. Jha

    2009-02-02T23:59:59.000Z

    Neutron stars are the most dense objects in the observable Universe and conventionally one uses nuclear theory to obtain the equation of state (EOS) of dense hadronic matter and the global properties of these stars. In this work, we review various aspects of nuclear matter within an effective Chiral model and interlink fundamental quantities both from nuclear saturation as well as vacuum properties and correlate it with the star properties.

  9. Gas only nozzle

    DOE Patents [OSTI]

    Bechtel, William Theodore (15 Olde Coach Rd., Scotia, NY 12302); Fitts, David Orus (286 Sweetman Rd., Ballston Spa, NY 12020); DeLeonardo, Guy Wayne (60 St. Stephens La., Glenville, NY 12302)

    2002-01-01T23:59:59.000Z

    A diffusion flame nozzle gas tip is provided to convert a dual fuel nozzle to a gas only nozzle. The nozzle tip diverts compressor discharge air from the passage feeding the diffusion nozzle air swirl vanes to a region vacated by removal of the dual fuel components, so that the diverted compressor discharge air can flow to and through effusion holes in the end cap plate of the nozzle tip. In a preferred embodiment, the nozzle gas tip defines a cavity for receiving the compressor discharge air from a peripheral passage of the nozzle for flow through the effusion openings defined in the end cap plate.

  10. Gas ampoule-syringe

    DOE Patents [OSTI]

    Gay, Don D. (Aiken, SC)

    1986-01-01T23:59:59.000Z

    A gas ampoule for the shipment and delivery of radioactive gases. The gas ampoule having a glass tube with serum bottle stopper on one end and a plunger tip in the opposite end all fitting in a larger plastic tube threaded on each end with absorbent between the tubes, is seated onto the internal needle assembly via a bushing associated with the plunger and locked into the syringe barrel via barrel-bushing locking caps. The design practically eliminates the possibility of personnel contamination due to an inadvertent exposure of such personnel to the contained radioactive gas.

  11. Gas ampoule-syringe

    DOE Patents [OSTI]

    Gay, D.D.

    1985-02-02T23:59:59.000Z

    A gas ampoule for the shipment and delivery of radioactive gases. The gas ampoule having a glass tube with serum bottle stopper on one and a plunger tip in the opposite end all fitting in a larger plastic tube threaded on each end with absorbent between the tubes, is seated onto the internal needle assembly via a bushing associated with the plunger and locked into the syringe barrel via barrel-bushing locking caps. The design practically eliminates the possibility of personnel contamination due to an inadvertent exposure of such personnel to the contained radioactive gas.

  12. Natural Gas | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    Fossil Natural Gas Natural Gas September 15, 2014 NETL Releases Hydraulic Fracturing Study The National Energy Technology Laboratory has released a technical report on the...

  13. Regulations For Gas Companies (Tennessee)

    Broader source: Energy.gov [DOE]

    The Regulations for Gas Companies, implemented by the Tennessee Regulatory Authority (Authority) outline the standards for metering, distribution and electricity generation for utilities using gas....

  14. Citizens Gas- Residential Efficiency Rebates

    Broader source: Energy.gov [DOE]

    Citizens Gas of Indiana offers rebates to its residential customers for the installation of several types of efficient natural gas appliances. Rebates are generally available for residential homes...

  15. Gas Water Heater Energy Losses

    E-Print Network [OSTI]

    Biermayer, Peter

    2012-01-01T23:59:59.000Z

    p. 163, January 1, 2005. Battelle, Assessment of Technologymodel, TANK, was developed by Battelle for the Gas Research93/0186. Prepared by Battelle for Gas Research Institute

  16. Historical Natural Gas Annual 1999

    U.S. Energy Information Administration (EIA) Indexed Site

    1999 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  17. Gas-Rich Companions of Isolated Galaxies

    E-Print Network [OSTI]

    Pisano, D J; Wilcots, Eric M.

    1999-01-01T23:59:59.000Z

    We have used the VLA to search for gaseous remnants of the galaxy formation process around six extremely isolated galaxies. We found two distinct HI clouds around each of two galaxies in our sample (UGC 9762 & UGC 11124). These clouds are rotating and appear to have optical counterparts, strongly implying that they are typical dwarf galaxies. The companions are currently weakly interacting with the primary galaxy, but have short dynamical friction timescales (~1 Gyr) suggesting that these triple galaxy systems will shortly collapse into one massive galaxy. Given that the companions are consistent with being in circular rotation about the primary galaxy, and that they have small relative masses, the resulting merger will be a minor one. The companions do, however, contain enough gas that the merger will represent a significant infusion of fuel to drive future star formation, bar formation, or central activity, while building up the mass of the disk thus making these systems important pieces of the galaxy f...

  18. Star Formation in the Gulf of Mexico

    E-Print Network [OSTI]

    Armond, Tina; Bally, John; Aspin, Colin

    2011-01-01T23:59:59.000Z

    We present an optical/infrared study of the dense molecular cloud, L935, dubbed "The Gulf of Mexico", which separates the North America and the Pelican nebulae, and we demonstrate that this area is a very active star forming region. A wide-field imaging study with interference filters has revealed 35 new Herbig-Haro objects in the Gulf of Mexico. A grism survey has identified 41 Halpha emission-line stars, 30 of them new. A small cluster of partly embedded pre-main sequence stars is located around the known LkHalpha 185-189 group of stars, which includes the recently erupting FUor HBC 722.

  19. Abundances of massive stars: some recent developments

    E-Print Network [OSTI]

    T. Morel

    2008-11-25T23:59:59.000Z

    Thanks to their usefulness in various fields of astrophysics (e.g. mixing processes in stars, chemical evolution of galaxies), the last few years have witnessed a large increase in the amount of abundance data for early-type stars. Two intriguing results emerging since the last reviews on this topic will be discussed: (a) nearby OB stars exhibit metal abundances generally lower than the solar/meteoritic estimates; (b) evolutionary models of single objects including rotation are largely unsuccessful in explaining the CNO properties of stars in the Galaxy and in the Magellanic clouds.

  20. A Galactic O-Star Catalog

    E-Print Network [OSTI]

    J. Maíz-Apellániz; N. R. Walborn; H. Á. Galué; L. H. Wei

    2003-11-09T23:59:59.000Z

    We have produced a catalog of 378 Galactic O stars with accurate spectral classifications which is complete for Vweb-based version with links to online services.

  1. ComEd, Nicor Gas, Peoples Gas & North Shore Gas- Small Business Energy Savings Program

    Broader source: Energy.gov [DOE]

    ComEd, Nicor Gas, Peoples Gas, and North Shore Gas fund the Small Business Energy Savings program in which an energy advisor conducts a free on-site energy assessment and provides free installati...

  2. ComEd, Nicor Gas, Peoples Gas and North Shore Gas- Bonus Rebate Program (Illinois)

    Broader source: Energy.gov [DOE]

    ComEd, Nicor Gas, Peoples Gas and North Shore Gas are offering a Complete System Replacement Rebate Program to residential customers. The program is a bundled promotion in partnership with ComEd...

  3. STARS Training Needs Assessment Learner Instructions 07/2009 1 STARS Training Needs Assessment

    E-Print Network [OSTI]

    Ford, James

    STARS Training Needs Assessment Learner Instructions 07/2009 1 STARS Training Needs Assessment. · Click the STARS (Training) tab. · Click My Training Needs in the left menu. · Click the secure link to continue to My Training Needs. On the Training Needs Assessment page, click the box to the left of every

  4. AP STAR AWARDS Who is the shining star in your department?

    E-Print Network [OSTI]

    AP STAR AWARDS Who is the shining star in your department? Give them the honor they deserve! Deadline for application is February 4, 2011 The AP Stars award was created to express appreciation individual performance at CSU. Anyone can nominate an AP employee for this award! The goal

  5. TURBOVELOCITY STARS: KICKS RESULTING FROM THE TIDAL DISRUPTION OF SOLITARY STARS

    SciTech Connect (OSTI)

    Manukian, Haik; Guillochon, James; Ramirez-Ruiz, Enrico [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); O'Leary, Ryan M., E-mail: jfg@ucolick.org [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2013-07-10T23:59:59.000Z

    The centers of most known galaxies host supermassive black holes (SMBHs). In orbit around these black holes are a centrally concentrated distribution of stars, both in single and in binary systems. Occasionally, these stars are perturbed onto orbits that bring them close to the SMBH. If the star is in a binary system, the three-body interaction with the SMBH can lead to large changes in orbital energy, depositing one of the two stars on a tightly-bound orbit, and its companion into a hyperbolic orbit that may escape the galaxy. In this Letter, we show that the disruption of solitary stars can also lead to large positive increases in orbital energy. The kick velocity depends on the amount of mass the star loses at pericenter, but not on the ratio of black hole to stellar mass, and are at most the star's own escape velocity. We find that these kicks are usually too small to result in the ejection of stars from the Milky Way, but can eject the stars from the black hole's sphere of influence, reducing their probability of being disrupted again. We estimate that {approx} 10{sup 5} stars, {approx} 1% of all stars within 10 pc of the galactic center, are likely to have had mass removed by the central black hole through tidal interaction, and speculate that these 'turbovelocity' stars will at first be redder, but eventually bluer, and always brighter than their unharassed peers.

  6. Natural gas monthly

    SciTech Connect (OSTI)

    NONE

    1996-05-01T23:59:59.000Z

    This document highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Data presented include volume and price, production, consumption, underground storage, and interstate pipeline activities.

  7. Greenhouse Gas Emissions (Minnesota)

    Broader source: Energy.gov [DOE]

    This statute sets goals for the reduction of statewide greenhouse gas emissions by at least 15 percent by 2015, 30 percent by 2025, and 80 percent by 2050, calculated relative to 2005 levels. These...

  8. Gas Turbine Emissions 

    E-Print Network [OSTI]

    Frederick, J. D.

    1990-01-01T23:59:59.000Z

    of regulatory interest in the 'real world' test results coupled with the difficulties of gathering analogous bench test data for systems employing gas turbines with Heat Recovery Steam Generators (HRSG) and steam injection. It appears that the agencies...

  9. Gas-Saving Tips

    Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (EERE)]

    Properly Tuned Fixing a car that is noticeably out of tune or has failed an emis- sions test can improve its gas mileage by an average of 4 percent. However, results vary based on...

  10. Fluid Inclusion Gas Analysis

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Dilley, Lorie

    Fluid inclusion gas analysis for wells in various geothermal areas. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

  11. Fluid Inclusion Gas Analysis

    SciTech Connect (OSTI)

    Dilley, Lorie

    2013-01-01T23:59:59.000Z

    Fluid inclusion gas analysis for wells in various geothermal areas. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

  12. Gas Pipelines (Texas)

    Broader source: Energy.gov [DOE]

    This chapter applies to any entity that owns, manages, operates, leases, or controls a pipeline for the purpose of transporting natural gas in the state for sale or compensation, as well as any...

  13. Gas Pipeline Securities (Indiana)

    Broader source: Energy.gov [DOE]

    This statute establishes that entities engaged in the transmission of gas by pipelines are not required to obtain the consent of the Utility Regulatory Commission for issuance of stocks,...

  14. Natural Gas Regulations (Kentucky)

    Broader source: Energy.gov [DOE]

    Kentucky Administrative Regulation title 805 promulgates the rules and regulations pertaining to natural gas production in Kentucky. In addition to KAR title 405, chapter 30, which pertains to any...

  15. (bulb) , (1) Gas(1) Gas(1) Gas(1) Gas----saturation methodsaturation methodsaturation methodsaturation method

    E-Print Network [OSTI]

    Hong, Deog Ki

    (bulb) , . . , . . 1. . (1) Gas(1Static MethodStatic Method Isoteniscope bulb U-tube . bulb U-tube bulb . bulb . U bulb . manometer . . Isoteniscope Boling Point Method . #12;2. (1) Boiling

  16. Natural gas repowering experience

    SciTech Connect (OSTI)

    Bautista, P.J.; Fay, J.M. [Gas Research Institute, Chicago, IL (United States); Gerber, F.B. [BENTEK Energy Research, DeSoto, TX (United States)

    1995-12-31T23:59:59.000Z

    Gas Research Institute has led a variety of projects in the past two years with respect to repowering with natural gas. These activities, including workshops, technology evaluations, and market assessments, have indicated that a significant opportunity for repowering exists. It is obvious that the electric power industry`s restructuring and the actual implementation of environmental regulations from the Clean Air Act Amendments will have significant impact on repowering with respect to timing and ultimate size of the market. This paper summarizes the results and implications of these activities in repowering with natural gas. It first addresses the size of the potential market and discusses some of the significant issues with respect to this market potential. It then provides a perspective on technical options for repowering which are likely to be competitive in the current environment. Finally, it addresses possible actions by the gas industry and GRI to facilitate development of the repowering market.

  17. (GAS HYDRATES) 2 ()

    E-Print Network [OSTI]

    : ... ... .... .... «» , 28 2007 : « » #12; · ·· #12; 2 #12; (GAS HYDRATES) #12;Y · µ 2 µ () µ · µ µ · µ µ µ ·µ: - - µ CO2 - - #12; - 3S·2M·1L·34H3S

  18. STAR METRICS | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page onYouTube YouTube Note: Since the.pdfBreakingMay 2015 <Department of iiBiodiesel |NYDepartmentOctober 10,TechnologySTAR

  19. Energy Star | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand JumpConceptual Model,DOEHazel Crest,EnergySerranopolis Jump to:EconCompaniesMainEnergyEnergyPublicStar

  20. Ultraviolet Spectrophotometry of Variable Early-Type Be and B stars Derived from High-Resolution IUE Data

    E-Print Network [OSTI]

    Myron A. Smith

    2001-07-10T23:59:59.000Z

    High-dispersion IUE data encode significant information about aggregate line absorptions that cannot be conveniently extracted from individual spectra. We apply a new technique in which fluxes from each echelle order of a short wavelength IUE spectrum are binned together to construct low-resolution spectra of a rapidly varying B or Be star. The ratio of binned spectra obtained bright- star and faint-star phases contains information about the mechanism responsible for a star's variability, such as from pulsations or occultations of the star by ejected matter. We model the variations caused by these mechanism by means of model atmosphere and absorbing-slab codes. Line absorptions strength changes are sensitive to conditions in circumstellar clouds with T = 8,000--13,000K. To demonstrate proofs of concept, we construct spectral ratios for circumstellar structures associated with flux variability in various Be stars: (1) Vela X1 has bow-shock wind trailing its neutron star companion and shows signatures of gas at 13,000K or 26,000K medium in different sectors, (2) 88 Her undergoes episodic outbursts as its UV flux fades, followed a year later by a dimming in visible wavelengths, a result of a gray opacity that dominates as the shell expands and cools, and (3) zeta Tau and 60 Cyg exhibit periodic spectrum and flux changes, which match model absorptions for occulting clouds. Also, ratioed UV spectra of strongly pulsating stars show unique spectrophotometric signatures which can be simulated with models. An analysis of ratioed spectra obtained for a typical sample of 18 classical Be stars known to have rapid periodic flux variations indicates that 13 of them have ratioed spectra which are relatively featureless or have signatures of pulsation. Ratioed spectra of 3 others in the sample are consistent with the presence of co-rotating clouds.

  1. Shale gas production: potential versus actual greenhouse gas emissions*

    E-Print Network [OSTI]

    Shale gas production: potential versus actual greenhouse gas emissions* Francis O, monitor and verify greenhouse gas emissions and climatic impacts. This reprint is one of a series intended Environ. Res. Lett. 7 (2012) 044030 (6pp) doi:10.1088/1748-9326/7/4/044030 Shale gas production: potential

  2. Oil and Gas CDT Coupled flow of water and gas

    E-Print Network [OSTI]

    Henderson, Gideon

    Oil and Gas CDT Coupled flow of water and gas during hydraulic fracture in shale The University of Oxford http://www.earth.ox.ac.uk/people/profiles/academic/joec Key Words Shale gas, hydraulic fracture, groundwater contamination, transport in porous media Overview Recovery of natural gas from mudstone (shale

  3. Planet formation around binary stars: Tatooine made easy

    E-Print Network [OSTI]

    Bromley, B C

    2015-01-01T23:59:59.000Z

    We examine characteristics of circumbinary orbits in the context of current planet formation scenarios. Analytical perturbation theory predicts the existence of nested circumbinary orbits that are generalizations of circular orbits in a Keplerian potential. They contain forced epicyclic motion aligned with the binary as well as higher frequency oscillations, yet they do not cross, even in the presence of massive disks and perturbations from large planets. For this reason, dissipative gas and planetesimals can settle onto these "most circular" orbits, facilitating the growth of protoplanets. Outside a region close to the binary where orbits are generally unstable, circumbinary planets form in much the same way as their cousins around a single star. Here, we review the theory and confirm its predictions with a suite of representative simulations. We then consider the circumbinary planets discovered with NASA's Kepler satellite. These Neptune- and Jupiter-size planets, or their planetesimal precursors, may have ...

  4. Three regimes of extrasolar planets inferred from host star metallicities

    E-Print Network [OSTI]

    Buchhave, Lars A; Latham, David W; Sasselov, Dimitar; Cochran, William D; Endl, Michael; Isaacson, Howard; Juncher, Diana; Marcy, Geoffrey W

    2014-01-01T23:59:59.000Z

    Approximately half of the extrasolar planets (exoplanets) with radii less than four Earth radii are in orbits with short periods. Despite their sheer abundance, the compositions of such planets are largely unknown. The available evidence suggests that they range in composition from small, high-density rocky planets to low-density planets consisting of rocky cores surrounded by thick hydrogen and helium gas envelopes. Understanding the transition from the gaseous planets to Earth-like rocky worlds is important to estimate the number of potentially habitable planets in our Galaxy and provide constraints on planet formation theories. Here we report the abundances of heavy elements (that is, the metallicities) of more than 400 stars hosting 600 exoplanet candidates, and find that the exoplanets can be categorized into three populations defined by statistically distinct (~ 4.5{\\sigma}) metallicity regions. We interpret these regions as reflecting the formation regimes of terrestrial-like planets (radii less than 1...

  5. Gas sampling system for reactive gas-solid mixtures

    DOE Patents [OSTI]

    Daum, Edward D. (Alliance, OH); Downs, William (Alliance, OH); Jankura, Bryan J. (Mogadore, OH); McCoury, Jr., John M. (Mineral City, OH)

    1990-01-01T23:59:59.000Z

    An apparatus and method for sampling gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extends in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  6. Gas sampling system for reactive gas-solid mixtures

    DOE Patents [OSTI]

    Daum, Edward D. (Alliance, OH); Downs, William (Alliance, OH); Jankura, Bryan J. (Mogadore, OH); McCoury, Jr., John M. (Mineral City, OH)

    1989-01-01T23:59:59.000Z

    An apparatus and method for sampling a gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extend in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  7. Fast Radio Bursts from Axion Stars

    E-Print Network [OSTI]

    Aiichi Iwazaki

    2015-04-20T23:59:59.000Z

    Axions are one of the most promising candidates of dark matter. The axions have been shown to form miniclusters with masses $\\sim 10^{-12}M_{\\odot}$, some of which condense to form axion stars. We have recently shown a possible origin of fast radio bursts ( FRBs ) by assuming that the axion stars are main component of halos: FRBs arise from the collisions between the axion stars and neutron stars. It is remarkable that the masses of the axion stars obtained by the comparison of the theoretical and observational event rates are coincident with the mass $\\sim 10^{-12}M_{\\odot}$. In this paper, we describe our model of FRBs in detail. We derive the approximate solutions of the axion stars with large radii and constraint their masses for the approximation to be valid. The FRBs are emitted from the atmospheres of neutron stars in the collisions. By calculating the optical depth of the atmospheres, we show that they are transparent for the radiations with the frequency given by the axion mass $m_a$ such as $m_a/2\\pi\\simeq 2.4$GHz$(m_a/10^{-5}\\rm eV)$. Although the radiations are linearly polarized when they are emitted, they are shown to be circularly polarized after they pass magnetospheres of neutron stars. We also show that the frequencies of the FRBs have finite bandwidths owing to the Doppler effect when the neutron stars pass through the axion stars. The presence of the finite bandwidths is a distinctive feature of our model and can be tested observationally. Furthermore, we show that similar FRBs may arise when the axion stars collide with magnetic white dwarfs. The characteristic feature is that the durations of the bursts are of the order of $0.1$second and they are monochromatic contrary to the FRBs observed. We can determine the axion mass by the observating both of the their frequencies and red shifts $z$.

  8. SMT CO (2-1) Observations of Nearby Star-Forming Galaxies

    E-Print Network [OSTI]

    Jiang, Xue-Jian; Gu, Qiusheng; Wang, Junzhi; Zhang, Zhi-Yu

    2014-01-01T23:59:59.000Z

    We present CO $J$=2-1 observations towards 32 nearby gas-rich star-forming galaxies selected from the ALFALFA and WISE catalogs, using the Sub-millimeter Telescope. Our sample is selected to be dominated by intermediate-$M_{\\rm *}$ galaxies. The scaling-relations between molecular gas, atomic gas and galactic properties (stellar mass, NUV$- r$ and WISE color W3$-$W2) are examined and discussed. Our results show that (1). In the galaxies with stellar mass $M_{\\rm *}$ $\\leqslant 10^{10}$ $M_{\\odot}$, HI fraction ($f_{\\rm HI}$ $\\equiv$ $M_{\\rm HI}$/$M_{\\rm *}$) is significantly higher than that of more massive galaxies, while H$_2$ gas fraction ($f_{\\rm H_2}$ $\\equiv$ $M_{\\rm H_2}$/$M_{\\rm *}$) remain nearly unchanged. (2). Comparing with $f_{\\rm H_2}$, $f_{\\rm HI}$ correlates better with both $M_{\\rm *}$ and NUV$- r$. (3). A new parameter, WISE color W3$-$W2 (12\\,$\\mu$m$-$4.6\\,$\\mu$m) is introduced, which is similar to NUV$- r$ in tracing star formation activity, and we find that W3$-$W2 has a tighter anti-corr...

  9. Storm fronts over galaxy discs: Models of how waves generate extraplanar gas and its anomalous kinematics

    E-Print Network [OSTI]

    Curtis Struck; Daniel C. Smith

    2009-05-15T23:59:59.000Z

    The existence of partially ionized, diffuse gas and dust clouds at kiloparsec scale distances above the central planes of edge-on, galaxy discs was an unexpected discovery about 20 yrs ago. Subsequent observations showed that this EDIG (extended or extraplanar diffuse interstellar gas) has rotation velocities approximately 10-20% lower than those in the central plane, and have been hard to account for. Here we present results of hydrodynamic models, with radiative cooling and heating from star formation. We find that in models with star formation generated stochastically across the disc an extraplanar gas layer is generated as long as the star formation is sufficiently strong. However, this gas rotates at nearly the same speed as the mid-plane gas. We then studied a range of models with imposed spiral or bar waves in the disc. EDIG layers were also generated in these models, but primarily over the wave regions, not over the entire disc. Because of this partial coverage, the EDIG clouds move radially, as well as vertically, with the result that observed kinematic anomalies are reproduced. The implication is that the kinematic anomalies are the result of three-dimensional motions when the cylindrical symmetry of the disc is broken. Thus, the kinematic anomalies are the result of bars or strong waves, and more face-on galaxies with such waves should have an asymmetric EDIG component. The models also indicate that the EDIG can contain a significant fraction of cool gas, and that some star formation can be triggered at considerable heights above the disc midplane. We expect all of these effects to be more prominent in young, forming discs, to play a role in rapidly smoothing disc asymmetries, and in working to self-regulate disc structure.

  10. HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer

    E-Print Network [OSTI]

    Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouille, G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M

    2011-01-01T23:59:59.000Z

    A gas analyzer system has been developed to analyze Hydrogen-Deuteride (HD) gas for producing frozen-spin polarized HD targets, which are used for hadron photoproduction experiments at SPring-8. Small amounts of ortho-H$_{2}$ and para-D$_{2}$ gas mixtures ($\\sim$0.01%) in the purified HD gas are a key to realize a frozen-spin polarized target. In order to obtain reliable concentrations of these gas mixtures in the HD gas, we produced a new gas analyzer system combining two independent measurements with the gas chromatography and the QMS. The para-H$_{2}$, ortho-H$_{2}$, HD, and D$_{2}$ are separated using the retention time of the gas chromatography and the mass/charge. It is found that the new gas analyzer system can measure small concentrations of $\\sim$0.01% for the otho-H$_2$ and D$_2$ with good S/N ratios.

  11. HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer

    E-Print Network [OSTI]

    T. Ohta; S. Bouchigny; J. -P. Didelez; M. Fujiwara; K. Fukuda; H. Kohri; T. Kunimatsu; C. Morisaki; S. Ono; G. Rouille; M. Tanaka; K. Ueda; M. Uraki; M. Utsuro; S. Y. Wang; M. Yosoi

    2011-01-28T23:59:59.000Z

    A gas analyzer system has been developed to analyze Hydrogen-Deuteride (HD) gas for producing frozen-spin polarized HD targets, which are used for hadron photoproduction experiments at SPring-8. Small amounts of ortho-H$_{2}$ and para-D$_{2}$ gas mixtures ($\\sim$0.01%) in the purified HD gas are a key to realize a frozen-spin polarized target. In order to obtain reliable concentrations of these gas mixtures in the HD gas, we produced a new gas analyzer system combining two independent measurements with the gas chromatography and the QMS. The para-H$_{2}$, ortho-H$_{2}$, HD, and D$_{2}$ are separated using the retention time of the gas chromatography and the mass/charge. It is found that the new gas analyzer system can measure small concentrations of $\\sim$0.01% for the otho-H$_2$ and D$_2$ with good S/N ratios.

  12. STAR-TO-STAR IRON ABUNDANCE VARIATIONS IN RED GIANT BRANCH STARS IN THE GALACTIC GLOBULAR CLUSTER NGC 3201

    SciTech Connect (OSTI)

    Simmerer, Jennifer; Ivans, Inese I.; Filler, Dan [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Francois, Patrick [Paris-Meudon Observatory, France and Universite de Picardie Jules Verne, F-80080 Amiens (France); Charbonnel, Corinne [Geneva Observatory, University of Geneva, Chemin des Maillettes 51, CH-1290 Versoix (Switzerland); Monier, Richard [Laboratoire Hippolyte Fizeau, Universite Nice Sophia Antipolis, Parc Valrose, F-06000 Nice (France); James, Gaeel, E-mail: jennifer@physics.utah.edu, E-mail: iii@physics.utah.edu, E-mail: dan.filler@utah.edu, E-mail: patrick.francois@obspm.fr, E-mail: corinne.charbonnel@unige.ch, E-mail: richard.monier@unice.fr, E-mail: gjames@eso.org [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Munchen (Germany)

    2013-02-10T23:59:59.000Z

    We present the metallicity as traced by the abundance of iron in the retrograde globular cluster NGC 3201, measured from high-resolution, high signal-to-noise spectra of 24 red giant branch stars. A spectroscopic analysis reveals a spread in [Fe/H] in the cluster stars at least as large as 0.4 dex. Star-to-star metallicity variations are supported both through photometry and through a detailed examination of spectra. We find no correlation between iron abundance and distance from the cluster core, as might be inferred from recent photometric studies. NGC 3201 is the lowest mass halo cluster to date to contain stars with significantly different [Fe/H] values.

  13. The dust mass in z > 6 normal star forming galaxies

    E-Print Network [OSTI]

    Mancini, Mattia; Graziani, Luca; Valiante, Rosa; Dayal, Pratika; Maio, Umberto; Ciardi, Benedetta; Hunt, Leslie K

    2015-01-01T23:59:59.000Z

    We interpret recent ALMA observations of z > 6 normal star forming galaxies by means of a semi-numerical method, which couples the output of a cosmological hydrodynamical simulation with a chemical evolution model which accounts for the contribution to dust enrichment from supernovae, asymptotic giant branch stars and grain growth in the interstellar medium. We find that while stellar sources dominate the dust mass of small galaxies, the higher level of metal enrichment experienced by galaxies with Mstar > 10^9 Msun allows efficient grain growth, which provides the dominant contribution to the dust mass. Even assuming maximally efficient supernova dust production, the observed dust mass of the z = 7.5 galaxy A1689-zD1 requires very efficient grain growth. This, in turn, implies that in this galaxy the average density of the cold and dense gas, where grain growth occurs, is comparable to that inferred from observations of QSO host galaxies at similar redshifts. Although plausible, the upper limits on the dust ...

  14. Parent Stars of Extrasolar Planets. VIII. Chemical Abundances for 18 Elements in 31 Stars

    E-Print Network [OSTI]

    Guillermo Gonzalez; Chris Laws

    2007-04-17T23:59:59.000Z

    We present the results of detailed spectroscopic abundance analyses for 18 elements in 31 nearby stars with planets. The resulting abundances are combined with other similar studies of nearby stars with planets and compared to a sample of nearby stars without detected planets. We find some evidence for abundance differences between these two samples for Al, Si and Ti. Some of our results are in conflict with a recent study of stars with planets in the SPOCS database. We encourage continued study of the abundance patterns of stars with planets to resolve these discrepancies.

  15. Origin of the Metallicity Dependence of Exoplanet Host Stars in the Protoplanetary Disk Mass Distribution

    E-Print Network [OSTI]

    M. C. Wyatt; C. J. Clarke; J. S. Greaves

    2007-07-18T23:59:59.000Z

    The probability of a star hosting a planet that is detectable in radial velocity surveys increases Ppl(Z) oc 10^2Z, where Z is metallicity. Core accretion models reproduce this trend, since the protoplanetary disk of a high metallicity star has a high density of solids and so forms cores which accrete gas before the primordial gas disk dissipates. This paper considers the origin of the form of Ppl(Z). We introduce a simple model in which detectable planets form when the mass of solids in the protoplanetary disk, Ms, exceeds a critical value. In this model the form of Ppl(Z) is a direct reflection of the distribution of protoplanetary disk masses, Mg, and the observed Ppl(Z) is reproduced if P(Mg>Mg') oc 1/Mg'^2. We argue that a protoplanetary disk's sub-mm dust mass is a pristine indicator of the mass available for planet-building and find the observed sub-mm disk mass distribution is consistent with the observed Ppl(Z) if Ms>0.5M_J is required to form detectable planets. Any planet formation model which imposes a critical solid mass for planet formation would reproduce the observed Ppl(Z), and core accretion models are empirically consistent with a threshold criterion. We identify 7 protoplanetary disks which, by rigid application of this criterion, would be expected to form detectable planets. A testable prediction is that Ppl(Z) should flatten both for Z>0.5dex and as more distant and lower mass planets are discovered. Further, combining this model with one in which the evolution of a star's debris disk is also influenced by the solid mass in its protoplanetary disk, results in the prediction that debris disks detected around stars with planets should be more infrared luminous than those around stars without planets in tentative agreement with recent observations.

  16. ON THE NATURE OF SMALL PLANETS AROUND THE COOLEST KEPLER STARS

    SciTech Connect (OSTI)

    Gaidos, Eric [Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Fischer, Debra A. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Mann, Andrew W. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Lepine, Sebastien, E-mail: gaidos@hawaii.edu [Department of Astrophysics, American Museum of Natural History, New York, NY 10024 (United States)

    2012-02-10T23:59:59.000Z

    We constrain the densities of Earth- to Neptune-size planets around very cool (T{sub e} = 3660-4660 K) Kepler stars by comparing 1202 Keck/HIRES radial velocity measurements of 150 nearby stars to a model based on Kepler candidate planet radii and a power-law mass-radius relation. Our analysis is based on the presumption that the planet populations around the two sets of stars are the same. The model can reproduce the observed distribution of radial velocity variation over a range of parameter values, but, for the expected level of Doppler systematic error, the highest Kolmogorov-Smirnov probabilities occur for a power-law index {alpha} Almost-Equal-To 4, indicating that rocky-metal planets dominate the planet population in this size range. A single population of gas-rich, low-density planets with {alpha} = 2 is ruled out unless our Doppler errors are {>=}5 m s{sup -1}, i.e., much larger than expected based on observations and stellar chromospheric emission. If small planets are a mix of {gamma} rocky planets ({alpha} = 3.85) and 1 - {gamma} gas-rich planets ({alpha} = 2), then {gamma} > 0.5 unless Doppler errors are {>=}4 m s{sup -1}. Our comparison also suggests that Kepler's detection efficiency relative to ideal calculations is less than unity. One possible source of incompleteness is target stars that are misclassified subgiants or giants, for which the transits of small planets would be impossible to detect. Our results are robust to systematic effects, and plausible errors in the estimated radii of Kepler stars have only moderate impact.

  17. Gas Storage Technology Consortium

    SciTech Connect (OSTI)

    Joel L. Morrison; Sharon L. Elder

    2006-09-30T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry-driven consortium was created-the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. This report addresses the activities for the quarterly period of July 1, 2006 to September 30, 2006. Key activities during this time period include: {lg_bullet} Subaward contracts for all 2006 GSTC projects completed; {lg_bullet} Implement a formal project mentoring process by a mentor team; {lg_bullet} Upcoming Technology Transfer meetings: {sm_bullet} Finalize agenda for the American Gas Association Fall Underground Storage Committee/GSTC Technology Transfer Meeting in San Francisco, CA. on October 4, 2006; {sm_bullet} Identify projects and finalize agenda for the Fall GSTC Technology Transfer Meeting, Pittsburgh, PA on November 8, 2006; {lg_bullet} Draft and compile an electronic newsletter, the GSTC Insider; and {lg_bullet} New members update.

  18. GAS STORAGE TECHNOLOGY CONSORTIUM

    SciTech Connect (OSTI)

    Robert W. Watson

    2004-04-17T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. To accomplish this objective, the project is divided into three phases that are managed and directed by the GSTC Coordinator. Base funding for the consortium is provided by the U.S. Department of Energy (DOE). In addition, funding is anticipated from the Gas Technology Institute (GTI). The first phase, Phase 1A, was initiated on September 30, 2003, and is scheduled for completion on March 31, 2004. Phase 1A of the project includes the creation of the GSTC structure, development of constitution (by-laws) for the consortium, and development and refinement of a technical approach (work plan) for deliverability enhancement and reservoir management. This report deals with the second 3-months of the project and encompasses the period December 31, 2003, through March 31, 2003. During this 3-month, the dialogue of individuals representing the storage industry, universities and the Department of energy was continued and resulted in a constitution for the operation of the consortium and a draft of the initial Request for Proposals (RFP).

  19. GAS STORAGE TECHNOLOGY CONSORTIUM

    SciTech Connect (OSTI)

    Robert W. Watson

    2004-07-15T23:59:59.000Z

    Gas storage is a critical element in the natural gas industry. Producers, transmission and distribution companies, marketers, and end users all benefit directly from the load balancing function of storage. The unbundling process has fundamentally changed the way storage is used and valued. As an unbundled service, the value of storage is being recovered at rates that reflect its value. Moreover, the marketplace has differentiated between various types of storage services, and has increasingly rewarded flexibility, safety, and reliability. The size of the natural gas market has increased and is projected to continue to increase towards 30 trillion cubic feet (TCF) over the next 10 to 15 years. Much of this increase is projected to come from electric generation, particularly peaking units. Gas storage, particularly the flexible services that are most suited to electric loads, is critical in meeting the needs of these new markets. In order to address the gas storage needs of the natural gas industry, an industry-driven consortium was created--the Gas Storage Technology Consortium (GSTC). The objective of the GSTC is to provide a means to accomplish industry-driven research and development designed to enhance operational flexibility and deliverability of the Nation's gas storage system, and provide a cost effective, safe, and reliable supply of natural gas to meet domestic demand. To accomplish this objective, the project is divided into three phases that are managed and directed by the GSTC Coordinator. Base funding for the consortium is provided by the U.S. Department of Energy (DOE). In addition, funding is anticipated from the Gas Technology Institute (GTI). The first phase, Phase 1A, was initiated on September 30, 2003, and was completed on March 31, 2004. Phase 1A of the project included the creation of the GSTC structure, development and refinement of a technical approach (work plan) for deliverability enhancement and reservoir management. This report deals with Phase 1B and encompasses the period April 1, 2004, through June 30, 2004. During this 3-month period, a Request for Proposals (RFP) was made. A total of 17 proposals were submitted to the GSTC. A proposal selection meeting was held June 9-10, 2004 in Morgantown, West Virginia. Of the 17 proposals, 6 were selected for funding.

  20. ARCHEOLOGY OF AN ANCIENT STAR

    SciTech Connect (OSTI)

    Fuhrmann, K.; Chini, R.; Haas, M.; Hackstein, M.; Ramolla, M. [Astronomisches Institut, Ruhr-Universitaet Bochum, Universitaetsstrasse 150, D-44801 Bochum (Germany); Bernkopf, J., E-mail: klaus@ing.iac.es [University of Applied Sciences Augsburg, An der Hochschule 1, D-86161 Augsburg (Germany)

    2012-12-20T23:59:59.000Z

    We report on the bright and late F-type star HR 3138, which, with respect to its chemistry in the [Mg/H]-[Fe/Mg] abundance plane, we identify as an old Population II member. Evolutionary tracks are, however, in conflict with this finding and instead imply an age of only {tau} = 5.6{sup -1.8}{sub +{sub 2.2}} Gyr (2{sigma}) for HR 3138. We discuss this controversy in light of existing high-precision radial velocity surveys that mostly exclude the case of a blue straggler primary and a white dwarf secondary. While it is realized that a stellar merger can principally solve the issue and there is indeed observational evidence for mass accretion on HR 3138 from the absence of lithium in its photosphere, we also consider the interesting circumstance that HR 3138 lies in the direction to the 350 pc distant, young open cluster NGC 2516. We point to the possibility that the progenitor cloud of this cluster may likewise account for former mass accretion and we argue in particular for a dynamical friction with this cloud as a plausible cause for the strikingly common Galactic rotational velocity of the field star and open cluster.

  1. Gas intrusion into SPR caverns

    SciTech Connect (OSTI)

    Hinkebein, T.E.; Bauer, S.J.; Ehgartner, B.L.; Linn, J.K.; Neal, J.T.; Todd, J.L.; Kuhlman, P.S.; Gniady, C.T. [Sandia National Labs., Albuquerque, NM (United States). Underground Storage Technology Dept.; Giles, H.N. [Dept. of Energy, Washington, DC (United States). Strategic Petroleum Reserve

    1995-12-01T23:59:59.000Z

    The conditions and occurrence of gas in crude oil stored in Strategic Petroleum Reserve, SPR, caverns is characterized in this report. Many caverns in the SPR show that gas has intruded into the oil from the surrounding salt dome. Historical evidence and the analyses presented here suggest that gas will continue to intrude into many SPR caverns in the future. In considering why only some caverns contain gas, it is concluded that the naturally occurring spatial variability in salt permeability can explain the range of gas content measured in SPR caverns. Further, it is not possible to make a one-to-one correlation between specific geologic phenomena and the occurrence of gas in salt caverns. However, gas is concluded to be petrogenic in origin. Consequently, attempts have been made to associate the occurrence of gas with salt inhomogeneities including anomalies and other structural features. Two scenarios for actual gas intrusion into caverns were investigated for consistency with existing information. These scenarios are gas release during leaching and gas permeation through salt. Of these mechanisms, the greater consistency comes from the belief that gas permeates to caverns through the salt. A review of historical operating data for five Bryan Mound caverns loosely supports the hypothesis that higher operating pressures reduce gas intrusion into caverns. This conclusion supports a permeability intrusion mechanism. Further, it provides justification for operating the caverns near maximum operating pressure to minimize gas intrusion. Historical gas intrusion rates and estimates of future gas intrusion are given for all caverns.

  2. Cooling of Color Superconducting Compact Stars

    E-Print Network [OSTI]

    David Blaschke

    2006-03-26T23:59:59.000Z

    We review the status of research on the cooling of compact stars, with emphasis on the influence of color superconducting quark matter phases. Although a consistent microscopic approach is not yet available, severe constraints on the phase structure of matter at high densities come from recent mass and cooling observations of compact stars.

  3. FAINT RADIO SOURCES AND STAR FORMATION HISTORY

    E-Print Network [OSTI]

    Waddington, Ian

    FAINT RADIO SOURCES AND STAR FORMATION HISTORY Deborah B. Haarsma 1 , R. Bruce Partridge 1 , Ian 85287­1504 USA Abstract. Faint extragalactic radio sources provide important information about the global history of star formation. Sensitive radio observations of the Hubble Deep Field and other fields

  4. Long Baseline Interferometry of Be Stars

    E-Print Network [OSTI]

    Olivier Chesneau; Thomas Rivinius

    2005-10-24T23:59:59.000Z

    We give an introduction to interferometrical concepts and their applicability to Be stars. The first part of the paper concentrates on a short historic overview and basic principles of two-beam interferometric observations. In the second part, the VLTI/MIDI instrument is introduced and its first results on Be stars, obtained on alpha Ara and delta Cen, are outlined.

  5. First Structure Formation and the First Stars

    E-Print Network [OSTI]

    Michael L. Norman; Tom Abel; Greg Bryan

    2000-05-11T23:59:59.000Z

    We discuss the results of recent 3D simulations of first structure formation in relationship to the formation of the first stars. On the basis of a new, high-resolution AMR simulation (spatial dynamic range = 30,000,000), we conclude that the first stars are likely to be massive.

  6. An Observational Look at Rotating Stars

    E-Print Network [OSTI]

    Wiita, Paul J.

    . The Doppler Effect induces a shift at each end of the star's spectrum as one limb recedes, while the other radial velocities and the resulting shifts in wavelength from the various parts of the star (Kaler 1989 be calculated, or perhaps even the angular velocity" (Abney 1877). The component of the radial velocity observed

  7. North Star Refrigerator: Order (2013-CE-5355)

    Broader source: Energy.gov [DOE]

    DOE ordered North Star Refrigerator Co., Inc. to pay a $8,000 civil penalty after finding North Star Refrigerator had failed to certify that any basic models of walk-in cooler and freezer components comply with the applicable energy conservation standards.

  8. Gas cleaning system and method

    DOE Patents [OSTI]

    Newby, Richard Allen

    2006-06-06T23:59:59.000Z

    A gas cleaning system for removing at least a portion of contaminants, such as halides, sulfur, particulates, mercury, and others, from a synthesis gas (syngas). The gas cleaning system may include one or more filter vessels coupled in series for removing halides, particulates, and sulfur from the syngas. The gas cleaning system may be operated by receiving gas at a first temperature and pressure and dropping the temperature of the syngas as the gas flows through the system. The gas cleaning system may be used for an application requiring clean syngas, such as, but not limited to, fuel cell power generation, IGCC power generation, and chemical synthesis.

  9. The molecular environment of massive star forming cores associated with Class II methanol maser emission

    E-Print Network [OSTI]

    S. N. Longmore; M. G. Burton; P. J. Barnes; T. Wong; C. R. Purcell; J. Ott

    2007-04-13T23:59:59.000Z

    Methanol maser emission has proven to be an excellent signpost of regions undergoing massive star formation (MSF). To investigate their role as an evolutionary tracer, we have recently completed a large observing program with the ATCA to derive the dynamical and physical properties of molecular/ionised gas towards a sample of MSF regions traced by 6.7 GHz methanol maser emission. We find that the molecular gas in many of these regions breaks up into multiple sub-clumps which we separate into groups based on their association with/without methanol maser and cm continuum emission. The temperature and dynamic state of the molecular gas is markedly different between the groups. Based on these differences, we attempt to assess the evolutionary state of the cores in the groups and thus investigate the role of class II methanol masers as a tracer of MSF.

  10. Synchrotron spectral index and interstellar medium densities of star-forming galaxies

    E-Print Network [OSTI]

    Basu, Aritra; Schmidt, Philip; Roy, Subhashis

    2015-01-01T23:59:59.000Z

    The spectral index of synchrotron emission is an important parameter in understanding the properties of cosmic ray electrons (CREs) and the interstellar medium (ISM). We determine the synchrotron spectral index ($\\alpha_{\\rm nt}$) of four nearby star-forming galaxies, namely NGC 4736, NGC 5055, NGC 5236 and NGC 6946 at sub-kpc linear scales. The $\\alpha_{\\rm nt}$ was determined between 0.33 and 1.4 GHz for all the galaxies. We find the spectral index to be flatter ($\\gtrsim -0.7$) in regions with total neutral (atomic + molecular) gas surface density, $\\Sigma_{\\rm gas} \\gtrsim \\rm 50~M_\\odot pc^{-2}$, typically in the arms and inner parts of the galaxies. In regions with $\\Sigma_{\\rm gas} \\lesssim \\rm 50~M_\\odot pc^{-2}$, especially in the interarm and outer regions of the galaxies, the spectral index steepens sharply to $emitting a...

  11. THE MASS-LOSS RETURN FROM EVOLVED STARS TO THE LARGE MAGELLANIC CLOUD. II. DUST PROPERTIES FOR OXYGEN-RICH ASYMPTOTIC GIANT BRANCH STARS

    SciTech Connect (OSTI)

    Sargent, Benjamin A.; Meixner, M.; Gordon, Karl D. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Srinivasan, S. [Institut d'Astrophysique de Paris, 98 bis, Boulevard Arago, Paris 75014 (France); Kemper, F.; Woods, Paul M. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Tielens, A. G. G. M. [Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Speck, A. K. [Physics and Astronomy Department, University of Missouri, Columbia, MO 65211 (United States); Matsuura, M. [Institute of Origins, Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Bernard, J.-Ph. [Centre d'Etude Spatiale des Rayonnements, 9 Av. du Colonel Roche, BP 44346, 31028 Toulouse Cedex 4 (France); Hony, S. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot DAPNIA/Service d'Astrophysique Bat. 709, CEA-Saclay F-91191 Gif-sur-Yvette Cedex (France); Indebetouw, R. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Marengo, M. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Sloan, G. C., E-mail: sargent@stsci.ed [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)

    2010-06-10T23:59:59.000Z

    We model multi-wavelength broadband UBVIJHK{sub s} and Spitzer IRAC and MIPS photometry and Infrared Spectrograph spectra from the SAGE and SAGE-Spectroscopy observing programs of two oxygen-rich asymptotic giant branch (O-rich AGB) stars in the Large Magellanic Cloud (LMC) using radiative transfer (RT) models of dust shells around stars. We chose a star from each of the bright and faint O-rich AGB populations found by earlier studies of the SAGE sample in order to derive a baseline set of dust properties to be used in the construction of an extensive grid of RT models of the O-rich AGB stars found in the SAGE surveys. From the bright O-rich AGB population, we chose HV 5715, and from the faint O-rich AGB population we chose SSTISAGE1C J052206.92-715017.6 (SSTSAGE052206). We found the complex indices of refraction of oxygen-deficient silicates from Ossenkopf et al. and a power law with exponential decay grain size distribution like what Kim et al. used but with {gamma} of -3.5, a {sub min} of 0.01 {mu}m, and a {sub 0} of 0.1 {mu}m to be reasonable dust properties for these models. There is a slight indication that the dust around the faint O-rich AGB may be more silica-rich than that around the bright O-rich AGB. Simple models of gas emission suggest a relatively extended gas envelope for the faint O-rich AGB star modeled, consistent with the relatively large dust shell inner radius for the same model. Our models of the data require the luminosity of SSTSAGE052206 and HV 5715 to be {approx}5100 L {sub sun} and {approx}36,000 L {sub sun}, respectively. This, combined with the stellar effective temperatures of 3700 K and 3500 K, respectively, that we find best fit the optical and near-infrared data, suggests stellar masses of {approx}3 M {sub sun} and {approx}7 M {sub sun}. This, in turn, suggests that HV 5715 is undergoing hot-bottom burning and that SSTSAGE052206 is not. Our models of SSTSAGE052206 and HV 5715 require dust shells of inner radius {approx}17 and {approx}52 times the stellar radius, respectively, with dust temperatures there of 900 K and 430 K, respectively, and with optical depths at 10 {mu}m through the shells of 0.095 and 0.012, respectively. The models compute the dust mass-loss rates for the two stars to be 2.0 x 10{sup -9} M{sub sun} yr{sup -1} and 2.3 x 10{sup -9} M{sub sun} yr{sup -1}, respectively. When a dust-to-gas mass ratio of 0.002 is assumed for SSTSAGE052206 and HV 5715, the dust mass-loss rates imply total mass-loss rates of 1.0 x 10{sup -6} M{sub sun} yr{sup -1} and 1.2 x 10{sup -6} M{sub sun} yr{sup -1}, respectively. These properties of the dust shells and stars, as inferred from our models of the two stars, are found to be consistent with properties observed or assumed by detailed studies of other O-rich AGB stars in the LMC and elsewhere.

  12. Gas releases from salt

    SciTech Connect (OSTI)

    Ehgartner, B.; Neal, J.; Hinkebein, T.

    1998-06-01T23:59:59.000Z

    The occurrence of gas in salt mines and caverns has presented some serious problems to facility operators. Salt mines have long experienced sudden, usually unexpected expulsions of gas and salt from a production face, commonly known as outbursts. Outbursts can release over one million cubic feet of methane and fractured salt, and are responsible for the lives of numerous miners and explosions. Equipment, production time, and even entire mines have been lost due to outbursts. An outburst creates a cornucopian shaped hole that can reach heights of several hundred feet. The potential occurrence of outbursts must be factored into mine design and mining methods. In caverns, the occurrence of outbursts and steady infiltration of gas into stored product can effect the quality of the product, particularly over the long-term, and in some cases renders the product unusable as is or difficult to transport. Gas has also been known to collect in the roof traps of caverns resulting in safety and operational concerns. The intent of this paper is to summarize the existing knowledge on gas releases from salt. The compiled information can provide a better understanding of the phenomena and gain insight into the causative mechanisms that, once established, can help mitigate the variety of problems associated with gas releases from salt. Outbursts, as documented in mines, are discussed first. This is followed by a discussion of the relatively slow gas infiltration into stored crude oil, as observed and modeled in the caverns of the US Strategic Petroleum Reserve. A model that predicts outburst pressure kicks in caverns is also discussed.

  13. ISM Masses and Star Formation at z = 1 to 6 ALMA Observations of Dust Continuum in 180 Galaxies in COSMOS

    E-Print Network [OSTI]

    Scoville, N; Aussel, H; Bout, P Vanden; Capak, P; Bongiorno, A; Casey, C M; Murchikova, L; Koda, J; Pope, A; Toft, S; Ivison, R; Sanders, D; Manohar, S; Lee, N

    2015-01-01T23:59:59.000Z

    ALMA Cycle 2 observations of the long wavelength dust emission in 180 star-forming (SF) galaxies are used to investigate the evolution of ISM masses at z = 1 to 6.4. The ISM masses exhibit strong increases from z = 0 to $\\rm $ = 1.15 and further to $\\rm $ = 2.2 and 4.8, particularly amongst galaxies above the SF galaxy main sequence (MS). The galaxies with highest SFRs at $\\rm $ = 2.2 and 4.8 have gas masses 100 times that of the Milky Way and gas mass fractions reaching 50 to 80\\%, i.e. gas masses 1 - 4$\\times$ their stellar masses. For the full sample of galaxies, we find a single, very simple SF law: $\\rm SFR \\propto M_{\\rm ISM}^{0.9}$, i.e. a `linear' dependence on the ISM mass -- on and above the MS. Thus, the galaxies above the MS are converting their larger ISM masses into stars on a timescale similar to those on the MS. At z $> 1$, the entire population of star-forming galaxies has $\\sim$5 - 10$\\times$ shorter gas depletion times ($\\sim0.2$ Gyr) than galaxies at low redshift. These {\\bf shorter deplet...

  14. ENERGY STAR for Homes - Building America Top Innovation | Department...

    Energy Savers [EERE]

    Innovation. See another example of a builder constructing to ENERGY STAR for Homes. Find case studies of Building America projects across the country that support ENERGY STAR for...

  15. ENERGY STAR® Guide to Energy Efficiency Competitions for Buildings...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ENERGY STAR Guide to Energy Efficiency Competitions for Buildings and Plants ENERGY STAR Guide to Energy Efficiency Competitions for Buildings and Plants This step-by-step...

  16. Clean Energy Action Star Governor Schwarzenegger to Keynote ARPA...

    Broader source: Energy.gov (indexed) [DOE]

    Action Star Governor Schwarzenegger to Keynote ARPA-E Energy Innovation Summit Clean Energy Action Star Governor Schwarzenegger to Keynote ARPA-E Energy Innovation Summit February...

  17. ENERGY STAR Portfolio Manager and Utility Benchmarking Programs...

    Energy Savers [EERE]

    ENERGY STAR Portfolio Manager and Utility Benchmarking Programs: Effectiveness as a Conduit to Utility Energy Efficiency Programs ENERGY STAR Portfolio Manager and Utility...

  18. Webinar: ENERGY STAR Hot Water Systems for High Performance Homes...

    Energy Savers [EERE]

    Webinar: ENERGY STAR Hot Water Systems for High Performance Homes Webinar: ENERGY STAR Hot Water Systems for High Performance Homes This presentation is from the Building America...

  19. NATURAL GAS STORAGE ENGINEERING Kashy Aminian

    E-Print Network [OSTI]

    Mohaghegh, Shahab

    NATURAL GAS STORAGE ENGINEERING Kashy Aminian Petroleum & Natural Gas Engineering, West Virginia University, Morgantown, WV, USA. Shahab D. Mohaghegh Petroleum & Natural Gas Engineering, West Virginia University, Morgantown, WV, USA. Keywords: Gas Storage, Natural Gas, Storage, Deliverability, Inventory

  20. The Isotopic Abundances of Magnesium in Stars

    E-Print Network [OSTI]

    Pamela Gay; David L. Lambert

    1999-11-11T23:59:59.000Z

    Isotopic abundance ratios 24^Mg:25^Mg:26^Mg are derived for 20 stars from high- resolution spectra of the MgH A-X 0-0 band at 5140AA. With the exception of the weak g-band giant HR 1299, the stars are dwarfs that sample the metallicity range -1.8 < [Fe/H] <0.0. The abundance of 25^Mg amd 26^Mg relative to the dominant isotope 24^Mg decreases with decreasing [Fe/H] in fair accord with predictions from a recent model of galactic chemical evolution in which the Mg isotopes are synthesised by massive stars. Several stars appear especially enriched in the heavier Mg isotopes suggesting contamination by material from the envelopes of intermediate-mass AGB stars.