Sample records for lone star hub

  1. 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...

  2. 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%.

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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,

  8. Hubs | Department of Energy

    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 for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHallNotSeventy years ofHonorsAbout »Hubs Hubs

  9. Intermodal Hubs Combi-terminal

    E-Print Network [OSTI]

    Texas at Austin, University of

    Intermodal Hubs Combi-terminal Modal Generation Points Multimodal Inland Terminals Nodal Centers Freight Villages Inland Ports Gueterverkehrszentren Freight Nodal Terminal Intermodal Terminals Interporti

  10. Congestion delays at hub airports

    E-Print Network [OSTI]

    St. George, Martin J.

    1986-01-01T23:59:59.000Z

    A deterministic model was developed to study the effects of inefficient scheduling on flight delays at hub airports. The model bases the delay calculation on published schedule data and on user-defined airport capacities. ...

  11. Hubs | 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.pdfBreaking of Blythe Solar PowerCommercialEnergy Star|documentHow toHow

  12. Live with the Energy Innovation Hub Directors

    Broader source: Energy.gov [DOE]

    Tune in today, Tuesday, March 6, 2012, at 2:15pm EST for a live discussion with our three Energy Innovation Hubs directors.

  13. 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...

  14. 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

  15. 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

  16. 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)

  17. 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

  18. Redesign of a wind turbine hub

    E-Print Network [OSTI]

    Hunter-Jones, Bridget I

    2014-01-01T23:59:59.000Z

    The current designs of wind turbine hubs contain many faults. The slew ring bearing that connects the blade to the hub takes on a large bending moment that in many cases causes the joints to fail and the blade to break ...

  19. Energy Department to Launch New Energy Innovation Hub Focused...

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

    to Launch New Energy Innovation Hub Focused on Advanced Batteries and Energy Storage Energy Department to Launch New Energy Innovation Hub Focused on Advanced Batteries and Energy...

  20. Energy Innovation Hub Report Shows Philadelphia-area Building...

    Office of Environmental Management (EM)

    Innovation Hub Report Shows Philadelphia-area Building Retrofits Could Support 23,500 Jobs Energy Innovation Hub Report Shows Philadelphia-area Building Retrofits Could Support...

  1. Energy Department Announces Launch of Energy Innovation Hub for...

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

    Launch of Energy Innovation Hub for Critical Materials Research Energy Department Announces Launch of Energy Innovation Hub for Critical Materials Research May 31, 2012 - 5:56pm...

  2. 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

  3. THE PLANAR HUB LOCATION PROBLEM: A PROBABILISTIC ...

    E-Print Network [OSTI]

    2012-11-21T23:59:59.000Z

    Nov 5, 2012 ... Aykin and Brown, [4]. ...... [8] J.F. Campbell, Integer programming formulations of discrete hub location problems, European J. of O.R.. 72(1994) ...

  4. EEB Hub: A Test Bed for Nationwide Energy Efficiency

    E-Print Network [OSTI]

    Hall, Sharon J.

    EEB Hub: A Test Bed for Nationwide Energy Efficiency Wednesday, May 1, 2013 11:00 a.m. - 12:00 p 2011, became the executive director of the Energy Efficient Buildings (EEB) HUB through the US

  5. Wind turbine rotor hub and teeter joint

    DOE Patents [OSTI]

    Coleman, Clint (Warren, VT); Kurth, William T. (Warren, VT); Jankowski, Joseph (Stowe, VT)

    1994-10-11T23:59:59.000Z

    A rotor hub is provided for coupling a wind turbine rotor blade and a shaft. The hub has a yoke with a body which is connected to the shaft, and extension portions which are connected to teeter bearing blocks, each of which has an aperture. The blocks are connected to a saddle which envelops the rotor blade by one or two shafts which pass through the apertures in the bearing blocks. The saddle and blade are separated by a rubber interface which provides for distribution of stress over a larger portion of the blade. Two teeter control mechanisms, which may include hydraulic pistons and springs, are connected to the rotor blade and to the yoke at extension portions. These control mechanisms provide end-of-stroke damping, braking, and stiffness based on the teeter angle and speed of the blade.

  6. Central Networks Low Carbon Hub Optimizing renewable energy resources...

    Open Energy Info (EERE)

    (Smart Grid Project) Jump to: navigation, search Project Name Central Networks Low Carbon Hub Optimizing renewable energy resources in Lincolnshire Country United Kingdom...

  7. 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

  8. Hubs, Centers, and Institutes | ornl.gov

    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 for4,645 3,625 1,006 492 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHallNotSeventy years ofHonorsAbout »Hubs

  9. SEAB Hubs+ Report | Department of Energy

    Office of Environmental Management (EM)

    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 for4,645 3,625 1,006 492 742 33 1112011 Strategic2 OPAM615_CostNSAR -DepartmentRetailEnergySEA-04: SpecialHubs+ Report SEAB

  10. SolarHub | 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:Ezfeedflag JumpID-f < RAPID‎SolarCity Corp Jump to: navigation, search Name:SolarHub Jump

  11. Assessment of natural ventilation potentials on free-form architecture design using CFD simulations: a Learning Hub building in Singapore

    E-Print Network [OSTI]

    Szu Cheng, CHIEN

    2013-01-01T23:59:59.000Z

    DESIGN USING CF D SIMULATIONS: A LEARNING HUB BUILDING INLearning Hub computational model. In order to build up the simulation

  12. 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

  13. Compression part of Egan Hub facility`s expansion

    SciTech Connect (OSTI)

    NONE

    1997-11-01T23:59:59.000Z

    Egan Hub Partners, L.P. (EHP), a subsidiary of Market Hub Partners (MHP), is the owner and operator of the Egan Hub Partners gas storage facility located near the town of Evangeline in south Louisiana. Located on the Jennings salt dome, EHP provides high-deliverability (injection and/or withdrawal capabilities on demand) salt storage, giving its customers rapid response to market fluctuation and demand. In addition to long-term storage contracts, EHP offers natural gas hub services using interruptible storage entitlements and multiple pipeline interchange flexibility. Hub services include wheeling, parking, loaning and balancing. The EHP facility was put into service in September 1995. EHP just completed the installation of a fourth compressor unit. This is the second unit to be put in service at the facility this year and is identical to the previous one. Hanover Compression packaged both units which consist of a Caterpillar G-3616 engine (4,450 hp) and an Ariel JGC-6 compressor. The units are configured to accommodate the wide operating range encountered at a natural gas salt dome storage facility and are designed to operate with a suction range of 600--900 psi and a discharge range of 800--3,000 psi.

  14. Coal slurry pipeline based midwest fuel hub

    SciTech Connect (OSTI)

    Huettenhain, H. [Bechtel Technology & Consulting San Francisco, CA (United States)

    1998-12-31T23:59:59.000Z

    Low sulfur Powder River Basin (PRB) coal is a sought after fuel to comply with the year 2000 emission regulation for utility boilers. PRB coal is presently not competitive East of the Mississippi mainly because of railroad switching requirements and boiler designs not compatible with the PRB fuel characteristics. The use of the Lakes for transportation is an exception. The Lakes shipping lanes however, are only open part of the year. It is proposed to construct a coal slurry pipeline from the center of Wyoming coalfields to a hub near Detroit with access to low cost waste energy from power generation stations. The coal slurry pipeline will transport up to 25 million tons per year of fine PRB coal which has been removed from the conventionally transported coal, namely coal transported by rail. The rail delivered coal will have less dust. The system fits the DOE Vision 21 concept to mine and utilize coal in highly efficient systems and with the least environmental impact. The PRB coal is of subbituminous rank and not directly compatible with the boilers in Michigan/Indiana/Ohio area, which are designed to burn bituminous coal. Upgrading of the PRB coal using the hydrothermal slurry upgrading process can transform the PRB coal into a higher Btu content fuel by removing a large portion of the inherent moisture. Such upgraded PRB coal has proven an excellent reactive fuel when burned conventionally as PC fuel, or even when burned in slurry form as Coal Water Fuel (CWF). The cost of the process can be recovered when the process is combined with a coal slurry pipeline transport system. The result is an upgraded competitive fuel or fuels, which can be used for co-firing or re-burning applications to reduce SO{sub 2} and NOx emissions of utility boilers. The fuels can be powdered for direct fuel injection into boilers or blast furnaces as well as CWF. Depending on the stability of the upgraded PRB coal, the pipeline product could also be dewatered and prepared for export. This paper describes the concept and preliminary cost information. It also reports on reactions of the industries, which could be involved in the complex system, namely, coal mining companies, railroads, pipeline operators, fuel suppliers, and utilities.

  15. Interface structure for hub and mass attachment in flywheel rotors

    DOE Patents [OSTI]

    Deteresa, S.J.; Groves, S.E.

    1998-06-02T23:59:59.000Z

    An interface structure is described for hub and mass attachment in flywheel rotors. The interface structure efficiently transmits high radial compression forces and withstands both large circumferential elongation and local stresses generated by mass-loading and hub attachments. The interface structure is comprised of high-strength fiber, such as glass and carbon, woven into an angle pattern which is about 45{degree} with respect to the rotor axis. The woven fiber is bonded by a ductile matrix material which is compatible with and adheres to the rotor material. This woven fiber is able to elongate in the circumferential direction to match the rotor growth during spinning. 2 figs.

  16. Interface structure for hub and mass attachment in flywheel rotors

    DOE Patents [OSTI]

    Deteresa, Steven J. (Livermore, CA); Groves, Scott E. (Brentwood, CA)

    1998-06-02T23:59:59.000Z

    An interface structure for hub and mass attachment in flywheel rotors. The interface structure efficiently transmits high radial compression forces and withstands both large circumferential elongation and local stresses generated by mass-loading and hub attachments. The interface structure is comprised of high-strength fiber, such as glass and carbon, woven into an angle pattern which is about 45.degree. with respect to the rotor axis. The woven fiber is bonded by a ductile matrix material which is compatible with and adheres to the rotor material. This woven fiber is able to elongate in the circumferential direction to match the rotor growth during spinning.

  17. Solution Structure of the Yeast Ubiquitin-Like Modifier Protein Hub1

    SciTech Connect (OSTI)

    Ramelot, Theresa A.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Cort, John R.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Yee, Adelinda (Ontario Cancer Institute) [Ontario Cancer Institute; Semsesi, Anthony (University of Toronto) [University of Toronto; Edwards, Aled M.(University of Toronto) [University of Toronto; Arrowsmith, Cheryl H.(9012) [9012; Kennedy, Michael A.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

    2003-12-01T23:59:59.000Z

    The Hub1 protein from Saccharomyces cerevisiae (NESG ID: YTYst190 / PIR: S78735/ GI: 7493880) is a ubiquitin-like modifier protein (UBL) that is essential for proper cell polarization during the formation of mating projections in S. cerevisiae. Hub1 conjugation to the cell polarity factors Sph1 and Hbt1 was required for their proper subcellular localization (1). Hub1 belongs to a conserved family of eukaryotic proteins. S. cerevisiae and human Hub1 share 65% identity. The sequence identity with ubiquitin is 22%. Here we describe the solution structure of Hub1 determined by NMR spectroscopy. We compare the structure of Hub1 to ubiquitin and find that although the overall fold is almost identical, critical surface residues in ubiquitin are not conserved in Hub1. These differences probably reflect the different functions of the UBL Hub1.

  18. U.S. Wind Manufacturing: Taller Hub Heights to Access Higher...

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

    U.S. Wind Manufacturing: Taller Hub Heights to Access Higher Wind Resources and Lower Cost of Energy U.S. Wind Manufacturing: Taller Hub Heights to Access Higher Wind Resources and...

  19. 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...

  20. 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...

  1. 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...

  2. "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...

  3. 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.

  4. 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...

  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. 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...

  8. 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

  9. 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

  10. 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

  11. 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

  12. Offshore Series Wind Turbine Variable Hub heights & rotor diameters

    E-Print Network [OSTI]

    Firestone, Jeremy

    3.6MW Offshore Series Wind Turbine GE Energy #12;Feature Variable Hub heights & rotor diameters-savings feature, considering the rigors of offshore power generation. The 3.6 MW offshore wind turbine also, for both on and offshore use. Special features include... As the world's first commercially available wind

  13. Energy Innovation Hubs: A Home for Scientific Collaboration

    SciTech Connect (OSTI)

    Chu, Steven

    2012-01-01T23:59:59.000Z

    Secretary Chu will host a live, streaming Q&A session with the directors of the Energy Innovation Hubs on Tuesday, March 6, at 2:15 p.m. EST. The directors will be available for questions regarding their teams' work and the future of American energy. Ask your questions in the comments below, or submit them on Facebook, Twitter (@energy), or send an e-mail to newmedia@hq.doe.gov, prior or during the live event. Dr. Hank Foley is the director of the Greater Philadelphia Innovation Cluster for Energy-Efficient Buildings, which is pioneering new data intensive techniques for designing and operating energy efficient buildings, including advanced computer modeling. Dr. Douglas Kothe is the director of the Consortium for Advanced Simulation of Light Water Reactors, which uses powerful supercomputers to create "virtual" reactors that will help improve the safety and performance of both existing and new nuclear reactors. Dr. Nathan Lewis is the director of the Joint Center for Artificial Photosynthesis, which focuses on how to produce fuels from sunlight, water, and carbon dioxide. The Energy Innovation Hubs are major integrated research centers, with researchers from many different institutions and technical backgrounds. Each hub is focused on a specific high priority goal, rapidly accelerating scientific discoveries and shortening the path from laboratory innovation to technological development and commercial deployment of critical energy technologies. Ask your questions in the comments below, or submit them on Facebook, Twitter (@energy), or send an e-mail to newmedia@energy.gov, prior or during the live event. The Energy Innovation Hubs are major integrated research centers, with researchers from many different institutions and technical backgrounds. Each Hub is focused on a specific high priority goal, rapidly accelerating scientific discoveries and shortening the path from laboratory innovation to technological development and commercial deployment of critical energy technologies. Dr. Hank Holey is the director of the Greater Philadelphia Innovation Cluster for Energy-Efficient Buildings, which is pioneering new data intensive techniques for designing and operating energy efficient buildings, including advanced computer modeling. Dr. Douglas Kothe is the director of the Modeling and Simulation for Nuclear Reactors Hub, which uses powerful supercomputers to create "virtual" reactors that will help improve the safety and performance of both existing and new nuclear reactors. Dr. Nathan Lewis is the director of the Joint Center for Artificial Photosynthesis Hub, which focuses on how to produce biofuels from sunlight, water, and carbon dioxide.

  14. Energy Innovation Hubs: A Home for Scientific Collaboration

    ScienceCinema (OSTI)

    Chu, Steven

    2013-05-29T23:59:59.000Z

    Secretary Chu will host a live, streaming Q&A session with the directors of the Energy Innovation Hubs on Tuesday, March 6, at 2:15 p.m. EST. The directors will be available for questions regarding their teams' work and the future of American energy. Ask your questions in the comments below, or submit them on Facebook, Twitter (@energy), or send an e-mail to newmedia@hq.doe.gov, prior or during the live event. Dr. Hank Foley is the director of the Greater Philadelphia Innovation Cluster for Energy-Efficient Buildings, which is pioneering new data intensive techniques for designing and operating energy efficient buildings, including advanced computer modeling. Dr. Douglas Kothe is the director of the Consortium for Advanced Simulation of Light Water Reactors, which uses powerful supercomputers to create "virtual" reactors that will help improve the safety and performance of both existing and new nuclear reactors. Dr. Nathan Lewis is the director of the Joint Center for Artificial Photosynthesis, which focuses on how to produce fuels from sunlight, water, and carbon dioxide. The Energy Innovation Hubs are major integrated research centers, with researchers from many different institutions and technical backgrounds. Each hub is focused on a specific high priority goal, rapidly accelerating scientific discoveries and shortening the path from laboratory innovation to technological development and commercial deployment of critical energy technologies. Ask your questions in the comments below, or submit them on Facebook, Twitter (@energy), or send an e-mail to newmedia@energy.gov, prior or during the live event. The Energy Innovation Hubs are major integrated research centers, with researchers from many different institutions and technical backgrounds. Each Hub is focused on a specific high priority goal, rapidly accelerating scientific discoveries and shortening the path from laboratory innovation to technological development and commercial deployment of critical energy technologies. Dr. Hank Holey is the director of the Greater Philadelphia Innovation Cluster for Energy-Efficient Buildings, which is pioneering new data intensive techniques for designing and operating energy efficient buildings, including advanced computer modeling. Dr. Douglas Kothe is the director of the Modeling and Simulation for Nuclear Reactors Hub, which uses powerful supercomputers to create "virtual" reactors that will help improve the safety and performance of both existing and new nuclear reactors. Dr. Nathan Lewis is the director of the Joint Center for Artificial Photosynthesis Hub, which focuses on how to produce biofuels from sunlight, water, and carbon dioxide.

  15. The Reliable Hub-and-spoke Design Problem: Models and Algorithms

    E-Print Network [OSTI]

    2011-05-31T23:59:59.000Z

    service between nodes and expanding capacities of hubs. [14] extend ... and MA models to derive an optimal network structure that maximizes the expected net-.

  16. DataHub project (Smart Grid Project) | 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,DOE Facility Database Data andDarnestown,ccd1-6885-43cf-8185-3b2c8e765008DataHub

  17. 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 ...

  18. Western Australian Hub of SiMERR Australia (National Centre of Science, ICT and

    E-Print Network [OSTI]

    SiMERR WA Western Australian Hub of SiMERR Australia (National Centre of Science, ICT and Mathematics Education for Rural and Regional Australia) Background Since 2005 SiMERR WA, the Western Australian Hub of SiMERR Australia, has been led by a team of academics from Curtin University. Si

  19. UBC Social Ecological Economic Development Studies (SEEDS) Student Report Energy & Buildings: Sustainable Strategies for Ponderosa Hub

    E-Print Network [OSTI]

    ENERGY & BUILDINGS: SUSTAINABLE STRATEGIES FOR PONDEROSA HUB #12;1 TABLE OF CONTENTS I.0 BackgroundUBC Social Ecological Economic Development Studies (SEEDS) Student Report Energy & Buildings: Sustainable Strategies for Ponderosa Hub Raphael Roy-Jauvin, Yael Haar, Hadi Kholeif, Natalia Pisarek

  20. Undergraduate Admissions for the 21st Conference in the Trinity Long Room Hub

    E-Print Network [OSTI]

    O'Mahony, Donal E.

    Undergraduate Admissions for the 21st Century Conference in the Trinity Long Room Hub Friday 18 May Foghlú. Part I 9.25 a.m. Dr. Patrick Prendergast (Provost of Trinity College Dublin), on `Undergraduate.m. Lunch in the Trinity Long Room Hub. #12;Part II The afternoon panel sessions will be chaired by Dr. John

  1. Department of Energy awards up to $120 million for battery hub...

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

    Video: The Joint Center for Energy Storage Research Photo Gallery Click to view the JCESR photo gallery Department of Energy awards up to 120 million for battery hub to...

  2. Development of Panama as a logistics hub and the impact on Latin America

    E-Print Network [OSTI]

    Muńoz, Daniel, M. Eng. Massachusetts Institute of Technology

    2010-01-01T23:59:59.000Z

    The Panamanian government is executing an aggressive economic growth initiative to transform the country into a regional logistics hub, like Singapore or Dubai. Two elements of the initiative are expansion of the Panama ...

  3. New Global Oil & Gas Hub in Oklahoma City | GE Global Research

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

    Selects Oklahoma City Site for New Global Hub of Oil & Gas Technology Innovation Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click...

  4. Welcome and Overview of Workshop and Energy Innovation Hubs Video (Text Version)

    Broader source: Energy.gov [DOE]

    This is a text version of the welcome and overview of the workshop and energy innovation hubs video presented at the Critical Materials Workshop, held on April 3, 2012 in Arlington, Virginia.

  5. 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.

  6. 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...

  7. Surface--micromachined rotatable member having a low-contact-area hub

    SciTech Connect (OSTI)

    Rodgers, M. Steven (Albuquerque, NM); Sniegowski, Jeffry J. (Edgewood, NM)

    2002-01-01T23:59:59.000Z

    A surface-micromachined rotatable member formed on a substrate and a method for manufacturing thereof are disclosed. The surface-micromachined rotatable member, which can be a gear or a rotary stage, has a central hub, and an annulus connected to the central hub by an overarching bridge. The hub includes a stationary axle support attached to the substrate and surrounding an axle. The axle is retained within the axle support with an air-gap spacing therebetween of generally 0.3 .mu.m or less. The rotatable member can be formed by alternately depositing and patterning layers of a semiconductor (e.g. polysilicon or a silicon-germanium alloy) and a sacrificial material and then removing the sacrificial material, at least in part. The present invention has applications for forming micromechanical or microelectromechanical devices requiring lower actuation forces, and providing improved reliability.

  8. Surface-micromachined rotatable member having a low-contact-area hub

    SciTech Connect (OSTI)

    Rodgers, M. Steven; Sniegowski, Jeffry J.; Krygowski, Thomas W.

    2003-11-18T23:59:59.000Z

    A surface-micromachined rotatable member formed on a substrate and a method for manufacturing thereof are disclosed. The surface-micromachined rotatable member, which can be a gear or a rotary stage, has a central hub, and an annulus connected to the central hub by an overarching bridge. The hub includes a stationary axle support attached to the substrate and surrounding an axle. The axle is retained within the axle support with an air-gap spacing therebetween of generally 0.3 .mu.m or less. The rotatable member can be formed by alternately depositing and patterning layers of a semiconductor (e.g. polysilicon or a silicon-germanium alloy) and a sacrificial material and then removing the sacrificial material, at least in part. The present invention has applications for forming micromechanical or microelectromechanical devices requiring lower actuation forces, and providing improved reliability.

  9. Hubs of brain functional networks are radically reorganized in comatose patients

    E-Print Network [OSTI]

    Boyer, Edmond

    Hubs of brain functional networks are radically reorganized in comatose patients S. Achard , C Human brain networks have topological properties in common with many other complex systems, prompting the question: what aspects of brain network organization are critical for distinctive functional properties

  10. Does CO2 Permeate through Aquaporin-1? Jochen S. Hub and Bert L. de Groot

    E-Print Network [OSTI]

    de Groot, Bert

    Does CO2 Permeate through Aquaporin-1? Jochen S. Hub and Bert L. de Groot Computational molecular dynamics simulations that address the question of CO2 permeation through human aquaporin-1. Free for a palmitoyloleoylphosphatidylethanolamine lipid bilayer membrane. The results indicate that significant aquaporin- 1-mediated CO2 permeation

  11. Macro-level Attention to Mobile Agent Security: Introducing the Mobile Agent Secure Hub Infrastructure Concept

    E-Print Network [OSTI]

    Roth, Volker

    for the safe management of mobile agents they deploy onto the Internet. Our in- frastructural approach is basedMacro-level Attention to Mobile Agent Security: Introducing the Mobile Agent Secure Hub Security Research Centre Queensland University of Technology Brisbane, Queensland, Australia and Dept

  12. Numerical Investigation of a Wind Turbine Rotor with an aerodynamically redesigned hub-region

    E-Print Network [OSTI]

    Numerical Investigation of a Wind Turbine Rotor with an aerodynamically redesigned hub-region J methods on a redesigned modern Mega-Watt sized wind turbine, where the new design includes an increase of the blade in the vicinity of the wind turbine nacelle, to obtain an aerodynamically more efficient rotor

  13. Why Do Hubs in the Yeast Protein Interaction Network Tend To Be Essential: Reexamining the Connection

    E-Print Network [OSTI]

    O'Leary, Dianne P.

    National Center of Biotechnology Information, National Library of Medicine, National Institutes of Health were supported by the Intramural Research Program of the NIH and the National Library of Medicine. DPO for the centrality-lethality rule, one relating the essentiality of hubs to their role in the overall network

  14. Establishment of a Hub for the Light Water Reactor Sustainability Online Monitoring Community

    SciTech Connect (OSTI)

    Nancy J. Lybeck; Magdy S. Tawfik; Binh T. Pham

    2011-08-01T23:59:59.000Z

    Implementation of online monitoring and prognostics in existing U.S. nuclear power plants will involve coordinating the efforts of national laboratories, utilities, universities, and private companies. Internet-based collaborative work environments provide necessary communication tools to facilitate interaction between geographically diverse participants. Available technologies were considered, and a collaborative workspace was established at INL as a hub for the light water reactor sustainability online monitoring community.

  15. Guidelines for reducing dynamic loads in two-bladed teetering-hub downwind wind turbines

    SciTech Connect (OSTI)

    Wright, A.D.; Bir, G.S.; Butterfield, C.D.

    1995-06-01T23:59:59.000Z

    A major goal of the federal Wind Energy Program is the rapid development and validation of structural models to determine loads and response for a wide variety of different wind turbine configurations operating under extreme conditions. Such codes are crucial to the successful design of future advanced wind turbines. In previous papers the authors described steps they took to develop a model of a two-bladed teetering-hub downwind wind turbine using ADAMS{reg_sign} (Automatic Dynamic Analysis of Mechanical Systems), as well as comparison of model predictions to test data. In this paper they show the use of this analytical model to study the influence of various turbine parameters on predicted system loads. They concentrate their study on turbine response in the frequency range of six to ten times the rotor rotational frequency (6P to 10P). Their goal is to identify the most important parameters which influence the response of this type of machine in this frequency range and give turbine designers some general design guidelines for designing two-bladed teetering-hub machines to be less susceptible to vibration. They study the effects of such parameters as blade edgewise and flapwise stiffness, tower top stiffness, blade tip-brake mass, low-speed shaft stiffness, nacelle mass momenta of inertia, and rotor speed. They show which parameters can be varied in order to make the turbine less responsive to such atmospheric inputs as wind shear and tower shadow. They then give designers a set of design guidelines in order to show how these machines can be designed to be less responsive to these inputs.

  16. 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.

  17. 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.

  18. Joint Center for Artificial Photosynthesis (JCAP): DOE's Solar Fuels Energy Innovation Hub (2011 EFRC Summit)

    ScienceCinema (OSTI)

    Lewis, Nate (Director, Joint Center for Artificial Photosynthesis and Professor at Caltech)

    2012-03-14T23:59:59.000Z

    The Joint Center for Artificial Photosynthesis (JCAP) is a DOE Energy Innovation Hub focused on fuels from sunlight. JCAP's Director, Nate Lewis, spoke at the 2011 EFRC Summit about what JCAP is and how it is partnering with the EFRC community to accelerate the progress towards new solar fuels. The 2011 EFRC Summit and Forum brought together the EFRC community and science and policy leaders from universities, national laboratories, industry and government to discuss "Science for our Nation's Energy Future." In August 2009, the Office of Science established 46 Energy Frontier Research Centers. The EFRCs are collaborative research efforts intended to accelerate high-risk, high-reward fundamental research, the scientific basis for transformative energy technologies of the future. These Centers involve universities, national laboratories, nonprofit organizations, and for-profit firms, singly or in partnerships, selected by scientific peer review. They are funded at $2 to $5 million per year for a total planned DOE commitment of $777 million over the initial five-year award period, pending Congressional appropriations. These integrated, multi-investigator Centers are conducting fundamental research focusing on one or more of several ?grand challenges? and use-inspired ?basic research needs? recently identified in major strategic planning efforts by the scientific community. The purpose of the EFRCs is to integrate the talents and expertise of leading scientists in a setting designed to accelerate research that transforms the future of energy and the environment.

  19. A Multi-Objective, Hub-and-Spoke Supply Chain Design Model For Densified Biomass

    SciTech Connect (OSTI)

    Md S. Roni; Sandra Eksioglu; Kara G. Cafferty

    2014-06-01T23:59:59.000Z

    In this paper we propose a model to design the supply chain for densified biomass. Rail is typically used for long-haul, high-volume shipment of densified biomass. This is the reason why a hub-and-spoke network structure is used to model this supply chain. The model is formulated as a multi-objective, mixed-integer programing problem under economic, environmental, and social criteria. The goal is to identify the feasibility of meeting the Renewable Fuel Standard (RFS) by using biomass for production of cellulosic ethanol. The focus in not just on the costs associated with meeting these standards, but also exploring the social and environmental benefits that biomass production and processing offers by creating new jobs and reducing greenhouse gas (GHG) emissions. We develop an augmented ?-constraint method to find the exact Pareto solution to this optimization problem. We develop a case study using data from the Mid-West. The model identifies the number, capacity and location of biorefineries needed to make use of the biomass available in the region. The model estimates the delivery cost of cellulosic ethanol under different scenario, the number new jobs created and the GHG emission reductions in the supply chain.

  20. 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...

  1. 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.

  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. 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.

  5. 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...

  6. 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.

  7. Preparation of Nucleic Acid Libraries for Personalized Sequencing Systems Using an Integrated Microfluidic Hub Technology (Seventh Annual Sequencing, Finishing, Analysis in the Future (SFAF) Meeting 2012)

    ScienceCinema (OSTI)

    Patel, Kamlesh D [Ken]; SNL,

    2013-01-25T23:59:59.000Z

    Kamlesh (Ken) Patel from Sandia National Laboratories (Livermore, California) presents "Preparation of Nucleic Acid Libraries for Personalized Sequencing Systems Using an Integrated Microfluidic Hub Technology " at the 7th Annual Sequencing, Finishing, Analysis in the Future (SFAF) Meeting held in June, 2012 in Santa Fe, NM.

  8. Spectral Modeling Hot Star Winds

    E-Print Network [OSTI]

    Cohen, David

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

  9. Savannah River Site Eastern Transportation Hub: A Concept For a DOE Eastern Packaging, Staging and Maintenance Center - 13143

    SciTech Connect (OSTI)

    England, Jeffery L. [Savannah River National Laboratory, Aiken, South Carolina (United States)] [Savannah River National Laboratory, Aiken, South Carolina (United States); Adams, Karen; Maxted, Maxcine; Ruff Jr, Clarence [U.S. Department of Energy, Savannah River Site, Aiken, SC (United States)] [U.S. Department of Energy, Savannah River Site, Aiken, SC (United States); Albenesius, Andrew; Bowers, Mark D.; Fountain, Geoffrey; Hughes, Michael [Savannah River Nuclear Solutions, Aiken, SC (United States)] [Savannah River Nuclear Solutions, Aiken, SC (United States); Gordon, Sydney [National Security Technologies, LLC, Las Vegas, NV (United States)] [National Security Technologies, LLC, Las Vegas, NV (United States); O'Connor, Stephen [U.S. Department of Energy, HQ DOE, EM-33, Germantown MD (United States)] [U.S. Department of Energy, HQ DOE, EM-33, Germantown MD (United States)

    2013-07-01T23:59:59.000Z

    The Department of Energy (DOE) is working to de-inventory sites and consolidate hazardous materials for processing and disposal. The DOE administers a wide range of certified shipping packages for the transport of hazardous materials to include Special Nuclear Material (SNM), radioactive materials, sealed sources and radioactive wastes. A critical element to successful and safe transportation of these materials is the availability of certified shipping packages. There are over seven thousand certified packagings (i.e., Type B/Type AF) utilized within the DOE for current missions. The synergistic effects of consolidated maintenance, refurbishment, testing, certification, and costing of these services would allow for efficient management of the packagings inventory and to support anticipated future in-commerce shipping needs. The Savannah River Site (SRS) receives and ships radioactive materials (including SNM) and waste on a regular basis for critical missions such as consolidated storage, stabilization, purification, or disposition using H-Canyon and HB-Line. The Savannah River National Laboratory (SRNL) has the technical capability and equipment for all aspects of packaging management. SRS has the only active material processing facility in the DOE complex and is one of the sites of choice for nuclear material consolidation. SRS is a logical location to perform maintenance and periodic testing of the DOE fleet of certified packagings. This initiative envisions a DOE Eastern Packaging Staging and Maintenance Center (PSMC) at the SRS and a western hub at the Nevada National Security Site (NNSS), an active DOE Regional Disposal Site. The PSMC's would be the first place DOE would go to meet their radioactive packaging needs and the primary locations projects would go to disposition excess packaging for beneficial reuse. These two hubs would provide the centralized management of a packaging fleet rather than the current approach to design, procure, maintain and dispose of packagings on a project-by-project basis. This initiative provides significant savings in packaging costs and acceleration of project schedules. In addition to certified packaging, the PSMC would be well suited for select designs of 7A Type A packaging and Industrial Packaging. (authors)

  10. 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 ...

  11. 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

  12. 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

  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. 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...

  15. 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 ...

  16. Regenerators As Hubs

    E-Print Network [OSTI]

    2013-09-26T23:59:59.000Z

    generator. Because it ... high set-up and operating costs of regeneration equipment prohibit employing ... variables and improve the problem formulations. ...... To speed up the separation of cut inequalities, we employ a three phase procedure.

  17. HUBs | Department of Energy

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

    ve-years-building-next-generation-reactors-0" target"blank">Consortium for the Advanced Simulation of Light Water Reactors (CASL), one of the Department's Energy Innovation...

  18. Solar Data Hub (Presentation)

    SciTech Connect (OSTI)

    Orwig, K.

    2011-04-01T23:59:59.000Z

    As power grid integration of renewables becomes ever more important and detailed, the need for a centralized place for solar-related resource data is needed. This presentation describes such a place and website.

  19. Critical Materials Hub

    Broader source: Energy.gov [DOE]

    Critical materials, including some rare earth elements that possess unique magnetic, catalytic, and luminescent properties, are key resources needed to manufacture products for the clean energy economy. These materials are so critical to the technologies that enable wind turbines, solar panels, electric vehicles, and energy-efficient lighting that DOE's 2010 and 2011 Critical Materials Strategy reported that supply challenges for five rare earth metals—dysprosium, neodymium, terbium, europium, and yttrium—could affect clean energy technology deployment in the coming years.1, 2

  20. Hubs | ornl.gov

    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 Science (SC) EnvironmentalGyroSolé(tm) HarmonicbetandEnergy 2010a WindEnergyHow

  1. DOE Energy Innovation Hubs

    Office of Science (SC) Website

    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:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron4 Self-Scrubbing:,,of ScienceCurrent ProjectsResearch » DOE Energy

  2. Energy Efficient Buildings Hub

    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't Your Destiny:RevisedAdvisoryStandard |in STEMEnergyI.of Energy Energy

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. The Department of Architectural Engineering is providing the technical leadership on the recently awarded Department of Energy Innovation Hub for Energy Efficient Buildings. This initiative was led on behalf of the

    E-Print Network [OSTI]

    Yener, Aylin

    awarded Department of Energy Innovation Hub for Energy Efficient Buildings. This initiative was led the building industry and radically improve the energy efficiency of building systems." See below, the Department should be playing a pivotal role in the development of the next generation of energy

  10. 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.

  11. 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)

  12. SmartGrid: Quarterly Data Summaries from the Data Hub and SmartGrid Project Information (from OpenEI and SmartGrid.gov)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Both OpenEI and SmartGrid.gov are DOE portals to a wealth of information about the federal initiatives that support the development of the technologies, policies and projects transforming the electric power industry. Projects funded through the U.S. Recovery Act are organized by type and pinned to an interactive map at http://en.openei.org/wiki/Gateway:Smart_Grid. Each project title links to more detailed information. The Quarterly Data Summaries from the Data Hub at SmartGrid.gov are also available on OpenEI at http://en.openei.org/datasets/node/928. In addition, the SmartGrid Information Center contains documents and reports that can be searched or browsed. Smart Grid Resources introduces international SmartGrid programs and sites, while OpenEI encourages users to add SmartGrid information to the repository.

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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 ...

  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. 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.

  15. 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...

  16. 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.

  17. 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....

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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...

  4. 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...

  5. 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

  6. 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...

  7. 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...

  8. 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.

  9. 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...

  10. Reflecting upon the Role of Memory in Meeting the Information Needs of Indigenous Mexican Migrants- The Memory Making Space of the Mixteco-Indi?gena Community Organizing Project (MICOP)

    E-Print Network [OSTI]

    Garibay, Javier Sepulveda

    2015-01-01T23:59:59.000Z

    get hub for community. Ventura County Star. Retrieved froms party draws hundreds. Ventura County Star. Retrieved fromOaxacan heritage celebration. Ventura County Star. Retrieved

  11. Signed Quality Assurance Hub Memo

    Office of Environmental Management (EM)

    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 for4,645 3,625 1,006 492 742 33 1112011 Strategic2Uranium Transfer toSensor Technologies for aShoshone-Bannock TribesShuttle :I

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. 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;...

  17. 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...

  18. 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.

  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. 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).

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Magnetic fields in Neutron Stars

    E-Print Network [OSTI]

    Viganň, 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.

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  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. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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

  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. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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.

  4. Gravitational waves from perturbed stars

    E-Print Network [OSTI]

    Valeria Ferrari

    2011-05-09T23:59:59.000Z

    Non radial oscillations of neutron stars are associated with the emission of gravitational waves. The characteristic frequencies of these oscillations can be computed using the theory of stellar perturbations, and they are shown to carry detailed information on the internal structure of the emitting source. Moreover, they appear to be encoded in various radiative processes, as for instance in the tail of the giant flares of Soft Gamma Repeaters. Thus, their determination is central to the theory of stellar perturbation. A viable approach to the problem consists in formulating this theory as a problem of resonant scattering of gravitational waves incident on the potential barrier generated by the spacetime curvature. This approach discloses some unexpected correspondences between the theory of stellar perturbations and the theory of quantum mechanics, and allows us to predict new relativistic effects.

  5. Adaptive Optics in Star Formation

    E-Print Network [OSTI]

    Wolfgang Brandner

    2003-09-29T23:59:59.000Z

    Over the past ten years, the concept of adaptive optics has evolved from early experimental stages to a standard observing tool now available at almost all major optical and near-infrared telescope facilities. Adaptive optics will also be essential in exploiting the full potential of the large optical/infrared interferometers currently under construction. Both observations with high-angular resolution and at high contrast, and with a high point source sensitivity are facilitated by adaptive optics. Among the areas which benefit most from the use of adaptive optics are studies of the circumstellar environment (envelopes, disks, outflows), substellar companions and multiple systems, and dense young stellar populations. This contribution highlights some of the recent advances in star formation studies facilitated by adaptive optics, and gives a brief tutorial on optimized observing and data reduction strategies.

  6. Methanol Masers and Star Formation

    E-Print Network [OSTI]

    A. M. Sobolev; A. B. Ostrovskii; M. S. Kirsanova; O. V. Shelemei; M. A. Voronkov; A. V. Malyshev

    2006-01-12T23:59:59.000Z

    Methanol masers which are traditionally divided into two classes provide possibility to study important parts of the star forming regions: Class~II masers trace vicinities of the massive YSOs while class~I masers are likely to trace more distant parts of the outflows where newer stars can form. There are many methanol transitions which produce observed masers. This allows to use pumping analysis for estimation of the physical parameters in the maser formation regions and its environment, for the study of their evolution. Extensive surveys in different masing transitions allow to conclude on the values of the temperatures, densities, dust properties, etc. in the bulk of masing regions. Variability of the brightest masers is monitored during several years. In some cases it is probably caused by the changes of the dust temperature which follow variations in the brightness of the central YSO reflecting the character of the accretion process. A unified catalogue of the class II methanol masers consisting of more than 500 objects is compiled. Analysis of the data shows that: physical conditions within the usual maser source vary considerably; maser brightness is determined by parameters of some distinguished part of the object - maser formation region; class II methanol masers are formed not within the outflows but in the regions affected by their propagation. It is shown that the "near" solutions for the kinematic distances to the sources can be used for statistical analysis. The luminosity function of the 6.7 GHz methanol masers is constructed. It is shown that improvement of the sensitivity of surveys can increase number of detected maser sources considerably.

  7. 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.

  8. WANDERING STARS: AN ORIGIN OF ESCAPED POPULATIONS

    SciTech Connect (OSTI)

    Teyssier, Maureen; Johnston, Kathryn V. [Department of Astronomy, Columbia University, Pupin Physics Laboratory, 550 West 120th Street, New York, NY 10027 (United States); Shara, Michael M. [American Museum of Natural History, 79th Street and Central Park West, New York, NY 10024-5192 (United States)

    2009-12-10T23:59:59.000Z

    We demonstrate that stars beyond the virial radii of galaxies may be generated by the gravitational impulse received by a satellite as it passes through the pericenter of its orbit around its parent. These stars may become energetically unbound (escaped stars), or may travel to further than a few virial radii for longer than a few Gyr, but still remain energetically bound to the system (wandering stars). Larger satellites (10%-100% the mass of the parent), and satellites on more radial orbits are responsible for the majority of this ejected population. Wandering stars could be observable on Mpc scales via classical novae, and on 100 Mpc scales via Type Ia supernova. The existence of such stars would imply a corresponding population of barely bound, old, high-velocity stars orbiting the Milky Way, generated by the same physical mechanism during the Galaxy's formation epoch. Sizes and properties of these combined populations should place some constraints on the orbits and masses of the progenitor objects from which they came, providing insight into the merging histories of galaxies in general and the Milky Way in particular.

  9. Beryllium abundances in stars hosting giant planets

    E-Print Network [OSTI]

    N. C. Santos; R. J. Garcia Lopez; G. Israelian; M. Mayor; R. Rebolo; A. Garcia-Gil; M. R. Perez de Taoro; S. Randich

    2002-02-25T23:59:59.000Z

    We have derived beryllium abundances in a wide sample of stars hosting planets, with spectral types in the range F7V-K0V, aimed at studying in detail the effects of the presence of planets on the structure and evolution of the associated stars. Predictions from current models are compared with the derived abundances and suggestions are provided to explain the observed inconsistencies. We show that while still not clear, the results suggest that theoretical models may have to be revised for stars with Teff<5500K. On the other hand, a comparison between planet host and non-planet host stars shows no clear difference between both populations. Although preliminary, this result favors a ``primordial'' origin for the metallicity ``excess'' observed for the planetary host stars. Under this assumption, i.e. that there would be no differences between stars with and without giant planets, the light element depletion pattern of our sample of stars may also be used to further investigate and constraint Li and Be depletion mechanisms.

  10. The Evolution of Compact Binary Star Systems

    E-Print Network [OSTI]

    Konstantin Postnov; Lev Yungelson

    2014-03-21T23:59:59.000Z

    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Mergings of compact binary stars are expected to be the most important sources for the forthcoming gravitational-wave (GW) astronomy. In the first part of the review, we discuss observational manifestations of close binary stars with NS and/or black components and their merger rate, crucial points in the formation and evolution of compact stars in binary systems, including the treatment of the natal kicks which NSs and BHs acquire during the core collapse of massive stars and the common envelope phase of binary evolution, which are most relevant to the merging rates of NS-NS, NS-BH and BH-BH binaries. The second part of the review is devoted mainly to formation and evolution of binary WDs and their observational manifestations, including their role as progenitors of cosmologically important thermonuclear SN Ia. We also consider AM CVn-stars which are thought to be the best verification binary GW sources for future low-frequency GW space interferometers.

  11. Luminous carbon stars in the Magellanic Clouds

    E-Print Network [OSTI]

    Jacco Th. van Loon; Albert A. Zijlstra; M. A. T. Groenewegen

    1999-02-19T23:59:59.000Z

    We present ground-based 3 micron spectra of obscured Asymptotic Giant Branch (AGB) stars in the Magellanic Clouds (MCs). We identify the carbon stars on the basis of the 3.1 micron absorption by HCN and C2H2 molecules. We show evidence for the existence of carbon stars up to the highest AGB luminosities (Mbol=-7 mag, for a distance modulus to the LMC of 18.7 mag). This proves that Hot Bottom Burning (HBB) cannot, in itself, prevent massive AGB stars from becoming carbon star before leaving the AGB. It also sets an upper limit to the distance modulus of the Large Magellanic Cloud of 18.8 mag. The equivalent width of the absorption band decreases with redder (K-L) colour when the dust continuum emission becomes stronger than the photospheric emission. Carbon stars with similar (K-L) appear to have equally strong 3 micron absorption in the MCs and the Milky Way. We discuss the implications for the carbon and nitrogen enrichment of the stellar photosphere of carbon stars.

  12. Comment on "Three-dimensional hydrodynamic simulations of the combustion of a neutron star into a quark star"

    E-Print Network [OSTI]

    M. I. Krivoruchenko; B. V. Martemyanov

    2015-03-04T23:59:59.000Z

    If strange matter is absolutely stable, the ordinary nuclei decay to strangelets, while neutron stars convert into strange stars. Lifetimes of the ordinary nuclei are constrained experimentally to be above $\\sim 10^{33}$ years, while lifetimes of the metastable neutron stars depend on the neutron star masses and can exceed the age of the Universe. As a consequence, the neutron stars and the strange stars can coexist in the Universe. We point out that numerical simulations of the conversion of neutron stars to strange stars, performed by M. Herzog and F. K. Roepke in Phys. Rev. D 84, 083002 (2011) [arXiv:1109.0539], are focused on a region in the parameter space of strange matter, in which low-mass neutron stars and strange stars are coexistent, whereas massive neutron stars are unstable and short lived on an astronomical timescale.

  13. Comment on "Three-dimensional hydrodynamic simulations of the combustion of a neutron star into a quark star"

    E-Print Network [OSTI]

    M. I. Krivoruchenko; B. V. Martemyanov

    2014-11-17T23:59:59.000Z

    If strange matter is absolutely stable, the ordinary nuclei decay to strangelets, while neutron stars convert into strange stars. Lifetimes of the ordinary nuclei are constrained experimentally to be above $\\sim 10^{33}$ years, while lifetimes of the metastable neutron stars depend on the neutron star masses and can exceed the age of the Universe. As a consequence, the neutron stars and the strange stars can coexist in the Universe. We point out that numerical simulations of the conversion of neutron stars to strange stars, performed by M. Herzog and F. K. Roepke in Phys. Rev. D 84, 083002 (2011) [arXiv:1109.0539], are focused on a region in the parameter space of strange matter, in which low-mass neutron stars and strange stars are coexistent, whereas massive neutron stars are unstable and short lived on an astronomical timescale.

  14. Do Si stars undergo any magnetic braking?

    E-Print Network [OSTI]

    P. North

    1998-02-23T23:59:59.000Z

    The old question of rotational braking of Ap Si stars is revisited on the empirical side, taking advantage of the recent Hipparcos results. Field stars with various evolutionary states are considered, and it is shown that the loose correlation between their rotational period and their surface gravity is entirely compatible with conservation of angular momentum. No evidence is found for any loss of angular momentum on the Main Sequence, which confirms earlier results based on less reliable estimates of surface gravity. The importance of reliable, fundamental Teff determinations of Bp and Ap stars is emphasized.

  15. Young stars and clouds in Camelopardalis

    E-Print Network [OSTI]

    V. Straizys; V. Laugalys

    2008-11-18T23:59:59.000Z

    Star formation in the Local spiral arm in the direction of the Galactic longitudes 132--158 deg is reviewed. Recent star-forming activity in this Milky Way direction is evidenced by the presence here of the Cam OB1 association and dense dust and molecular clouds containing H$\\alpha$ emission stars, young irregular variables and infrared stellar objects. The clouds of the Local arm concentrate in two layers at 150-300 pc and at about 900 pc from the Sun. The Perseus arm objects in this direction are at a distance of about 2 kpc.

  16. Convection and dynamo action in B stars

    E-Print Network [OSTI]

    Augustson, Kyle C; Toomre, Juri

    2010-01-01T23:59:59.000Z

    Main-sequence massive stars possess convective cores that likely harbor strong dynamo action. To assess the role of core convection in building magnetic fields within these stars, we employ the 3-D anelastic spherical harmonic (ASH) code to model turbulent dynamics within a 10 solar mass main-sequence (MS) B-type star rotating at 4 times the solar rate. We find that strong (900 kG) magnetic fields arise within the turbulence of the core and penetrate into the stably stratified radiative zone. These fields exhibit complex, time-dependent behavior including reversals in magnetic polarity and shifts between which hemisphere dominates the total magnetic energy.

  17. Lithium abundances in exoplanet-hosts stars

    E-Print Network [OSTI]

    M. Castro; S. Vauclair; O. Richard; N. C. Santos

    2008-03-20T23:59:59.000Z

    Exoplanet-host stars (EHS) are known to present surface chemical abundances different from those of stars without any detected planet (NEHS). EHS are, on the average, overmetallic compared to the Sun. The observations also show that, for cool stars, lithium is more depleted in EHS than in NEHS. The overmetallicity of EHS may be studied in the framework of two different scenarii. We have computed main sequence stellar models with various masses, metallicities and accretion rates. The results show different profiles for the lithium destruction according to the scenario. We compare these results to the spectroscopic observations of lithium.

  18. The evolution of very massive stars

    E-Print Network [OSTI]

    H. Belkus; J. Van Bever; D. Vanbeveren

    2007-01-11T23:59:59.000Z

    Core collapse of dense massive star clusters is unavoidable and this leads to the formation of massive objects, with a mass up to 1000 $\\msun$ and even larger. When these objects become stars, stellar wind mass loss determines their evolution and final fate, and decides upon whether they form black holes (with normal mass or with intermediate mass) or explode as a pair instability supernova. In the present paper, we discuss the evolution of very massive stars and we present a convenient evolution recipe that can be implemented in a gravitational N-body code to study the dynamics of dense massive clusters.

  19. Combustion of a neutron star into a strange quark star: the neutrino signal

    E-Print Network [OSTI]

    Pagliara, G; Ropke, F K

    2013-01-01T23:59:59.000Z

    There are strong indications that the process of conversion of a neutron star into a strange quark star proceeds as a strong deflagration implying that in a few milliseconds almost the whole star is converted. Starting from the three-dimensional hydrodynamic simulations of the combustion process which provide the temperature profiles inside the newly born strange star, we calculate for the first time the neutrino signal that is to be expected if such a conversion process takes place. The neutrino emission is characterized by a luminosity and a duration that is typical for the signal expected from protoneutron stars and represents therefore a powerful source of neutrinos which could be possibly directly detected in case of events occurring close to our galaxy. We discuss moreover possible connections between the birth of strange stars and explosive phenomena such as Supernovae and Gamma-Ray-Bursts.

  20. Combustion of a neutron star into a strange quark star: The neutrino signal

    E-Print Network [OSTI]

    G. Pagliara; M. Herzog; F. K. Roepke

    2013-05-02T23:59:59.000Z

    There are strong indications that the process of conversion of a neutron star into a strange quark star proceeds as a strong deflagration implying that in a few milliseconds almost the whole star is converted. Starting from the three-dimensional hydrodynamic simulations of the combustion process which provide the temperature profiles inside the newly born strange star, we calculate for the first time the neutrino signal that is to be expected if such a conversion process takes place. The neutrino emission is characterized by a luminosity and a duration that is typical for the signal expected from protoneutron stars and represents therefore a powerful source of neutrinos which could be possibly directly detected in case of events occurring close to our Galaxy. We discuss moreover possible connections between the birth of strange stars and explosive phenomena such as supernovae and gamma-ray-bursts.

  1. Blue Straggler Stars in Galactic Open Clusters and the effect of field star contamination

    E-Print Network [OSTI]

    G. Carraro; R. A. Vazquez; A. Moitinho

    2008-02-25T23:59:59.000Z

    We investigate the distribution of Blue Straggler stars in the field of three open star clusters. The main purpose is to highlight the crucial role played by general Galactic disk fore-/back-ground field stars, which are often located in the same region of the Color Magnitude Diagram as Blue Straggler stars. We analyze photometry taken from the literature of 3 open clusters of intermediate/old age rich in Blue Straggler stars, and which are projected in the direction of the Perseus arm, and study their spatial distribution and the Color Magnitude Diagram. As expected, we find that a large portion of the Blue Straggler population in these clusters are simply young field stars belonging to the spiral arm. This result has important consequences on the theories of the formation and statistics of Blue Straggler stars in different population environments: open clusters, globular clusters or dwarf galaxies. As previously emphasized by many authors, a detailed membership analysis is mandatory before comparing the Blue Straggler population in star clusters against theoretical models. Moreover, these sequences of young field stars (blue plumes) are potentially powerful tracers of Galactic structure which require further consideration.

  2. A POLYHEDRAL INVESTIGATION OF STAR COLORINGS 1 ...

    E-Print Network [OSTI]

    2015-01-13T23:59:59.000Z

    We consider a positive integer k and the corresponding polytope P? k(G), which is the convex ... Moreover, Lyons [26] investigates classes of graphs for which the star chromatic number .... Taking the partitioning in Figure 1(b), however, we.

  3. Folk Song 2, Sun, Moon, and Star

    E-Print Network [OSTI]

    Sgrol dkar skyid

    ?????????????????????????????????? ???????????? Tape No. / Track / Item No. Sitaigou Tibetan Folk Song 2.WAV Length of track 00:02:40 Related tracks (include description/relationship if appropriate) Title of track Sun?Moon, and Star ???????? ???????????? Translation of title...

  4. Identifying seasonal stars in Kaurna astronomical traditions

    E-Print Network [OSTI]

    Hamacher, Duane W

    2015-01-01T23:59:59.000Z

    Early ethnographers and missionaries recorded Aboriginal languages and oral traditions across Australia. Their general lack of astronomical training resulted in misidentifications, transcription errors, and omissions in these records. Additionally, many of these early records are fragmented. In western Victoria and southeast South Australia, many astronomical traditions were recorded, but curiously, some of the brightest stars in the sky were omitted. Scholars claimed these stars did not feature in Aboriginal traditions. This under-representation continues to be repeated in the literature, but current research shows that some of these stars may in fact feature in Aboriginal traditions and could be seasonal calendar markers. This paper uses established techniques in cultural astronomy to identify seasonal stars in the traditions of the Kaurna Aboriginal people of the Adelaide Plains, South Australia.

  5. Whirlpool: ENERGY STAR Referral (ASD2524VE)

    Broader source: Energy.gov [DOE]

    DOE referred the matter of Whirlpool's Amana-brand dishwasher model ASD2524VE to the EPA for appropriate action after DOE testing showed that the model does not meet the ENERGY STAR specification.

  6. ENERGY STAR® Solid-State Lighting Workshop

    Broader source: Energy.gov [DOE]

    Workshop Purpose: To prepare manufacturers for the launch of the ENERGY STAR SSL program in late September by sharing information on the state of the SSL market, status of relevant test procedures,...

  7. Binary star systems and extrasolar planets

    E-Print Network [OSTI]

    Muterspaugh, Matthew Ward

    2005-01-01T23:59:59.000Z

    For ten years, planets around stars similar to the Sun have been discovered, confirmed, and their properties studied. Planets have been found in a variety of environments previously thought impossible. The results have ...

  8. The Maximum Mass of a Neutron Star

    E-Print Network [OSTI]

    Vassiliki Kalogera; Gordon Baym

    1996-08-11T23:59:59.000Z

    Observational identification of black holes as members of binary systems requires the knowledge of the upper limit on the gravitational mass of a neutron star. We use modern equations of state for neutron star matter, fitted to experimental nucleon-nucleon scattering data and the properties of light nuclei, to calculate, within the framework of Rhoades & Ruffini (1974), the minimum upper limit on a neutron star mass. Regarding the equation of state as valid up to twice nuclear matter saturation density, rho_{nm}, we obtain a secure upper bound on the neutron star mass equal to 2.9 solar masses. We also find that in order to reach the lowest possible upper bound of 2.2 solar masses, we need understand the physical properties of neutron matter up to a density of about 4 times rho_{nm}.

  9. EPA ENERGY STAR Webcast- 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;...

  10. EPA ENERGY STAR Webcast- Portfolio Manager 101

    Office of Energy Efficiency and Renewable Energy (EERE)

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

  11. ENERGY STAR Webinar: Portfolio Manager 101

    Office of Energy Efficiency and Renewable Energy (EERE)

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

  12. Axion Stars and Fast Radio Bursts

    E-Print Network [OSTI]

    A. Iwazaki

    2014-10-23T23:59:59.000Z

    We show that fast radio bursts arise from collisions between axion stars and neutron stars. The bursts are emitted in the atmosphere of the neutron stars. The observed frequencies of the bursts are given by the axion mass $m_a$ such as $m_a/2\\pi\\simeq 1.4\\,\\mbox{GHz}\\,\\big(m_a/(6\\times 10^{-6}\\mbox{eV})\\big)$. From the event rate $\\sim 10^{-3}$ per year in a galaxy, we can determine the mass $\\sim 10^{-11}M_{\\odot}$ of the axion stars. Using these values we can explain short durations ( $\\sim $ms ) and amount of radiation energies ( $\\sim 10^{43}$GeV ) of the bursts.

  13. Jennifer Granholm (Energy All Stars Presentation)

    Broader source: Energy.gov [DOE]

    Former Michigan Governor Jennifer Granholm delivered this presentation advocating for an energy Race to the Top competition between the states at the Energy All Stars event on January 19, 2013, at...

  14. Probing axions with radiation from magnetic stars

    SciTech Connect (OSTI)

    Lai Dong; Heyl, Jeremy [Center for Radiophysics and Space Research, Department of Astronomy, Cornell University, Ithaca, New York 14853 (United States); Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, V6T 1Z1 (Canada)

    2006-12-15T23:59:59.000Z

    Recent experiments suggest that polarized photons may couple significantly to pseudoscalar particles such as axions. We study the possible observational signatures of axion-photon coupling for radiation from magnetic stars, with particular focus on neutron stars. We present general methods for calculating the axion-photon conversion probability during propagation through a varying magnetized vacuum as well as across an inhomogeneous atmosphere. Partial axion-photon conversion may take place in the vacuum region outside the neutron star. Strong axion-photon mixing occurs due to a resonance in the atmosphere and, depending on the axion coupling strength and other parameters, significant axion-photon conversion can take place at the resonance. Such conversions may produce observable effects on the radiation spectra and polarization signals from the star. We also apply our results to axion-photon propagation in the Sun and in magnetic white dwarfs. We find that there is no appreciable conversion of solar axions to photons during the propagation.

  15. Electron stars for holographic metallic criticality

    SciTech Connect (OSTI)

    Hartnoll, Sean A.; Tavanfar, Alireza [Center for the Fundamental Laws of Nature, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2011-02-15T23:59:59.000Z

    We refer to the ground state of a gravitating, charged ideal fluid of fermions held at a finite chemical potential as an ''electron star.'' In a holographic setting, electron stars are candidate gravity duals for strongly interacting finite fermion density systems. We show how electron stars develop an emergent Lifshitz scaling at low energies. This IR scaling region is a consequence of the two-way interaction between emergent quantum critical bosonic modes and the finite density of fermions. By integrating from the IR region to an asymptotically AdS{sub 4} spacetime, we compute basic properties of the electron stars, including their electrical conductivity. We emphasize the challenge of connecting UV and IR physics in strongly interacting finite density systems.

  16. Entropy & viscosity bound of strange stars

    E-Print Network [OSTI]

    Sibasish Laha; Taparati Gangopadhyay; Manjari Bagchi; Mira Dey; Jishnu Dey; Monika Sinha; Subharthi Ray

    2007-02-08T23:59:59.000Z

    At finite temperature (T) there is a link with general relativity and hydrodynamics that leads to a lower bound for the ratio of shear viscosity and entropy density (\\eta/s). We find that the bound is saturated in the simple model for quark matter that we use for strange stars at T = 80 MeV, at the surface of a strange star. At this T we have the possibility of cosmic separation of phases. We find that, although strongly correlated, the quark matter at the surface of strange stars constitute the most perfect interacting fluid permitted by nature. At the centre of the star, however, the density is higher and conditions are more like the results found for perturbative QCD.

  17. Home Performance with Energy Star Program

    Broader source: Energy.gov [DOE]

    The New Jersey Board of Public Utilities (NJ BPU) offers a Home Performance with Energy Star Program for residents that want to improve the energy efficiency of their homes. The program is set up...

  18. Simulations Reveal Unusual Death for Ancient Stars

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

    these objects-among the Universe's first-generation of stars-would have exploded as supernovae and burned completely, leaving no remnant black hole behind. Astrophysicists at the...

  19. Electron stars for holographic metallic criticality

    E-Print Network [OSTI]

    Sean A. Hartnoll; Alireza Tavanfar

    2011-01-06T23:59:59.000Z

    We refer to the ground state of a gravitating, charged ideal fluid of fermions held at a finite chemical potential as an `electron star'. In a holographic setting, electron stars are candidate gravity duals for strongly interacting finite fermion density systems. We show how electron stars develop an emergent Lifshitz scaling at low energies. This IR scaling region is a consequence of the two way interaction between emergent quantum critical bosonic modes and the finite density of fermions. By integrating from the IR region to an asymptotically AdS_4 spacetime, we compute basic properties of the electron stars, including their electrical conductivity. We emphasize the challenge of connecting UV and IR physics in strongly interacting finite density systems.

  20. Relativistic harmonic oscillator model for quark stars

    E-Print Network [OSTI]

    Vishnu M. Bannur

    2008-10-06T23:59:59.000Z

    The relativistic harmonic oscillator (RHO) model of hadrons is used to study quark stars. The mass-radius relationship is obtained and compared with bag model of quark star, using Tolman-Oppenheimer-Volkoff equation. In this model, the outward degenerate pressure due to discrete Landau levels and Landau degeneracy balances the inward gravitational pressure. Where as in bag model the degenerate pressure is due to the standard continuum levels which balances the combined inward pressure due to gravitation and bag pressure. So in RHO model, the confinement effect is included in the degenerate pressure. We found a qualitative similarity, but quantitative differences in mass-radius relationship of quark stars in these two models. Masses and radii are relatively larger and the central energy densities, required for stable quark stars, are lower in RHO model than that of bag model.

  1. Samsung: ENERGY STAR Referral (RF26VAB)

    Broader source: Energy.gov [DOE]

    DOE referred the matter of Samsung refrigerator-freezer model RF26VAB to the EPA for appropriate action after DOE testing showed that the model does not meet the ENERGY STAR specification.

  2. Cylindrically Symmetric Models of Anisotropic Compact Stars

    E-Print Network [OSTI]

    G. Abbas; Sumara Nazeer; M. A. Meraj

    2014-12-16T23:59:59.000Z

    In this paper we have discussed the possibility of forming anisotropic compact stars from cosmological constant as one of the competent candidates of dark energy with cylindrical symmetry. For this purpose, we have applied the analytical solution of Krori and Barua metric to a particular cylindrically symmetric spacetime. The unknown constants in Krori and Barua metric have been determined by using masses and radii of class of compact stars like 4$U$1820-30, Her X-1, SAX J 1808-3658. The properties of these stars have been analyzed in detail. In this setting the cosmological constant has been taken as a variable which depends on the radial coordinates. We have checked all the regularity conditions, stability and surface redshift of the compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658.

  3. Pulsational models of BL Her stars

    E-Print Network [OSTI]

    M. Di Criscienzo; M. Marconi; F. Caputo; S. Cassisi

    2007-12-05T23:59:59.000Z

    We present an updated and homogeneous pulsational scenario for a wide range of stellar parameters typical of BL Her stars i.e., Population II Cepheids with periods shorter than 8 days.

  4. Noncommutative Gauge Theory with Covariant Star Product

    SciTech Connect (OSTI)

    Zet, G. [Physics Department, 'Gh. Asachi' Technical University, 700050 Iasi (Romania)

    2010-08-04T23:59:59.000Z

    We present a noncommutative gauge theory with covariant star product on a space-time with torsion. In order to obtain the covariant star product one imposes some restrictions on the connection of the space-time. Then, a noncommutative gauge theory is developed applying this product to the case of differential forms. Some comments on the advantages of using a space-time with torsion to describe the gravitational field are also given.

  5. Top 10 Problems on Massive Stars

    E-Print Network [OSTI]

    Cassio Barbosa; Donald Figer

    2005-10-18T23:59:59.000Z

    We have asked a number of researchers to compile their lists of the top 10 problems in the field of massive stars. This paper is a compilation of these lists. We attempted to survey observers and theorists and those studying all evolutionary stages in the lives of massive stars. Each list reflects the proposer's personal point of view, but hopefully, this compilation will motivate new young astronomers and begin a new series of discussion.

  6. 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.

  7. On surface tension for compact stars

    E-Print Network [OSTI]

    R. Sharma; S. D. Maharaj

    2007-08-24T23:59:59.000Z

    In an earlier treatment it was demonstrated that general relativity gives higher values of surface tension in strange stars with quark matter than neutron stars.We generate the modified Tolman-Oppenheimer-Volkoff equation to incorporate anisotropic matter and use this to show that pressure anisotropy provides for a wide range of behaviour in the surface tension than is the case with isotropic pressures. In particular it is possible that anisotropy drastically decreases the value of the surface tension.

  8. Isotopic Anomalies in CP Stars: Helium, Mercury, Platinum, and Calcium

    E-Print Network [OSTI]

    C. R. Cowley; S. Hubrig; F. Castelli

    2007-11-15T23:59:59.000Z

    We review the classical observational results for isotopic abundance variations for several elements in CP stars. We concentrate on the "newest" anomaly, in calcium. The cosmically very rare isotope, Ca-48 can rival and even dominate the more common, alpha nuclide, Ca-40. Relevant examples are found in the hot, non-magnetic HgMn stars, and the field horizontal-branch star, Feige 86. The calcium anomaly is also present in cool, magnetic stars, including the notorious HD 101065, Przybylski's star.

  9. Neutron star in presence of torsion-dilaton field

    E-Print Network [OSTI]

    T. Boyadjiev; P. Fiziev; S. Yazadjiev

    1999-07-22T23:59:59.000Z

    We develop the general theory of stars in Saa's model of gravity with propagating torsion and study the basic stationary state of neutron star. Our numerical results show that the torsion force decreases the role of the gravity in the star configuration leading to significant changes in the neutron star masses depending on the equation of state of star matter. The inconsistency of the Saa's model with Roll-Krotkov-Dicke and Braginsky-Panov experiments is discussed.

  10. Magnetic braking of T Tauri stars

    E-Print Network [OSTI]

    P. J. Armitage; C. J. Clarke

    1995-12-05T23:59:59.000Z

    We construct models for the rotation rates of T Tauri stars whose spin is regulated by magnetic linkage between the star and a surrounding accretion disc. Our models utilise a time-dependent disc code to follow the accretion process and include the effects of pre-main-sequence stellar evolution. We find that the initial disc mass controls the evolution of the star-disc system. For sufficiently massive discs, a stellar field of $\\sim$ 1 kG is able to regulate the spin rate to the observed values during the classical T Tauri phase. The field then acts to expel the disc and the star spins up at constant angular momentum as a weak-line system. Lower mass discs are ejected at an early epoch and fail to brake the star significantly. We extend the model to close binary systems, and find that the removal of angular momentum from the disc by the secondary significantly prolongs the inner disc lifetime. Such systems should therefore be relatively slow rotators. We also discuss the implications of our model for the spectral energy distributions and variability of T Tauri stars.

  11. r-Process Enhanced Halo Stars

    E-Print Network [OSTI]

    J. J. Cowan; C. Sneden; J. E. Lawler; E. A. Den Hartog

    2006-10-13T23:59:59.000Z

    Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the earliest generations of stars in the Galaxy -- the progenitors of the halo stars -- responsible for neutron-capture synthesis of the heavy elements. The large star-to-star scatter observed in the abundances of neutron-capture element/iron ratios at low metallicities -- which diminishes with increasing metallicity or [Fe/H] -- suggests the formation of these heavy elements (presumably from certain types of supernovae) was rare in the early Galaxy. The stellar abundances also indicate a change from the r-process to the slow neutron capture (i.e., s-) process at higher metallicities in the Galaxy and provide insight into Galactic chemical evolution. Finally, the detection of thorium and uranium in halo and globular cluster stars offers an independent age-dating technique that can put lower limits on the age of the Galaxy, and hence the Universe.

  12. The properties of planets around giant stars

    E-Print Network [OSTI]

    Jones, M I; Bluhm, P; Rojo, P; Melo, C H F

    2014-01-01T23:59:59.000Z

    Context: More than 50 exoplanets have been found around giant stars, revealing different properties when compared to planets orbiting solar-type stars. In particular, they are Super-Jupiters and are not found orbiting interior to $\\sim$ 0.5 AU. Aims: We are conducting a radial velocity study of a sample of 166 giant stars aimed at studying the population of close-in planets orbiting giant stars and how their orbital and physical properties are influenced by the post-MS evolution of the host star. Methods: We have collected multi epochs spectra for all of the targets in our sample. We have computed precision radial velocities from FECH/CHIRON and FEROS spectra, using the I$_2$ cell technique and the simultaneous calibration method, respectively. Results: We present the discovery of a massive planet around the giant star HIP105854. The best Keplerian fit to the data leads to an orbital distance of 0.81 $\\pm$ 0.03 AU, an eccentricity of 0.02 $\\pm$ 0.03 and a projected mass of 8.2 $\\pm$ 0.2 \\mjup. With the additi...

  13. Experimental approach to neutron stars

    SciTech Connect (OSTI)

    Leifels, Yvonne [GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

    2014-05-09T23:59:59.000Z

    The equation of state (EOS) of nuclear matter is of fundamental importance in many areas of nuclear physics and astrophysics In the laboratory, there are different means to study the nuclearmatter equation of state and its density dependence in particular: nuclear masses, neutron skins, pygmy resonance, and nuclear structure at the drip line give access to nuclear matter properties at densities lower than and at saturation density ?0. Heavy ion reactions at energies above 0.1 AGeV are the only means to study nuclear matter at densities larger than normal nuclear matter density ?0. In the beamenergy range of 0.1 to 2A GeV nuclear matter is compressed upto three times ?0. Access to nuclear matter properties is achieved by simulating nuclear collisions by means of microscopic transport codes, or statistical or hydrodynamicalmodels. Characteristics of heavy-ion collisions are discussed, and experimental observables which allow to constrain nuclear matter properties by comparing experimental results with those of transport codes are presented. Special emphasis will be given to the density dependence of the symmetry energy which is the most relevant connection between neutron stars and heavy ion collisions.

  14. Massive stars on the verge of exploding: the properties of oxygen sequence Wolf-Rayet stars

    E-Print Network [OSTI]

    Tramper, F; Sanyal, D; Sana, H; de Koter, A; Gräfener, G; Langer, N; Vink, J S; de Mink, S E; Kaper, L

    2015-01-01T23:59:59.000Z

    Context. Oxygen sequence Wolf-Rayet (WO) stars represent a very rare stage in the evolution of massive stars. Their spectra show strong emission lines of helium-burning products, in particular highly ionized carbon and oxygen. The properties of WO stars can be used to provide unique constraints on the (post-)helium burning evolution of massive stars, as well as their remaining lifetime and the expected properties of their supernovae. Aims. We aim to homogeneously analyse the currently known presumed-single WO stars to obtain the key stellar and outflow properties and to constrain their evolutionary state. Methods. We use the line-blanketed non-local thermal equilibrium atmosphere code cmfgen to model the X-Shooter spectra of the WO stars and deduce the atmospheric parameters. We calculate dedicated evolutionary models to determine the evolutionary state of the stars. Results. The WO stars have extremely high temperatures that range from 150 kK to 210 kK, and very low surface helium mass fractions that range f...

  15. EPA ENERGY STAR Webinar: How to Apply for the ENERGY STAR

    Broader source: Energy.gov [DOE]

    The U.S. Environmental Protection Agency (EPA) is hosting a webinar on how to apply 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 help your property get from application to award.

  16. Search for OB stars running away from young star clusters. I. NGC 6611

    E-Print Network [OSTI]

    V. V. Gvaramadze; D. J. Bomans

    2009-03-04T23:59:59.000Z

    N-body simulations have shown that the dynamical decay of the young (~1 Myr) Orion Nebula cluster could be responsible for the loss of at least half of its initial content of OB stars. This result suggests that other young stellar systems could also lose a significant fraction of their massive stars at the very beginning of their evolution. To confirm this expectation, we used the Mid-Infrared Galactic Plane Survey (completed by the Midcourse Space Experiment satellite) to search for bow shocks around a number of young ($\\la$ several Myr) clusters and OB associations. We discovered dozens of bow shocks generated by OB stars running away from these stellar systems, supporting the idea of significant dynamical loss of OB stars. In this paper, we report the discovery of three bow shocks produced by O-type stars ejected from the open cluster NGC6611 (M16). One of the bow shocks is associated with the O9.5Iab star HD165319, which was suggested to be one of "the best examples for isolated Galactic high-mass star formation" (de Wit et al. 2005, A&A, 437, 247). Possible implications of our results for the origin of field OB stars are discussed.

  17. The neutron star mass distribution

    SciTech Connect (OSTI)

    Kiziltan, Bülent [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kottas, Athanasios; De Yoreo, Maria [Department of Applied Mathematics and Statistics, University of California, Santa Cruz, CA 95064 (United States); Thorsett, Stephen E., E-mail: bkiziltan@cfa.harvard.edu [Department of Astronomy and Astrophysics, University of California and UCO/Lick Observatory, Santa Cruz, CA 95064 (United States)

    2013-11-20T23:59:59.000Z

    In recent years, the number of pulsars with secure mass measurements has increased to a level that allows us to probe the underlying neutron star (NS) mass distribution in detail. We critically review the radio pulsar mass measurements. For the first time, we are able to analyze a sizable population of NSs with a flexible modeling approach that can effectively accommodate a skewed underlying distribution and asymmetric measurement errors. We find that NSs that have evolved through different evolutionary paths reflect distinctive signatures through dissimilar distribution peak and mass cutoff values. NSs in double NS and NS-white dwarf (WD) systems show consistent respective peaks at 1.33 M {sub ?} and 1.55 M {sub ?}, suggesting significant mass accretion (?m ? 0.22 M {sub ?}) has occurred during the spin-up phase. The width of the mass distribution implied by double NS systems is indicative of a tight initial mass function while the inferred mass range is significantly wider for NSs that have gone through recycling. We find a mass cutoff at ?2.1 M {sub ?} for NSs with WD companions, which establishes a firm lower bound for the maximum NS mass. This rules out the majority of strange quark and soft equation of state models as viable configurations for NS matter. The lack of truncation close to the maximum mass cutoff along with the skewed nature of the inferred mass distribution both enforce the suggestion that the 2.1 M {sub ?} limit is set by evolutionary constraints rather than nuclear physics or general relativity, and the existence of rare supermassive NSs is possible.

  18. Novel Geometrical Models of Relativistic Stars. II. Incompressible Stars and Heavy Black Dwarfs

    E-Print Network [OSTI]

    P. P. Fiziev

    2004-09-20T23:59:59.000Z

    In a series of articles we describe a novel class of geometrical models of relativistic stars. Our approach to the static spherically symmetric solutions of Einstein equations is based on a careful physical analysis of radial gauge conditions. It turns out that there exist heavy black dwarfs: relativistic stars with arbitrary large mass, which are to have arbitrary small radius and arbitrary small luminosity. In the present article we mathematically prove this new phenomena, using a detailed consideration of incompressible GR stars. We study the whole two parameter family of solutions of extended TOV equations for incompressible stars. This example is used to illustrate most of the basic features of the new geometrical models of relativistic stars. Comparison with newest observational data is discussed

  19. Rebates for ENERGY STAR Appliances: State Stories | 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 DataDepartment of Energy Your Density Isn'tOrigin of ContaminationHubs+18, 2012 Qualified11Department of EnergyFiltersReassessment

  20. Lone Tree, Colorado: Energy Resources | 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 YouKizildere I Geothermal Pwer Plant Jump to:Landowners andLodgepole, Nebraska: EnergyLomita, California:Londontowne,Tree,

  1. The star pile in Abell 545

    E-Print Network [OSTI]

    R. Salinas; T. Richtler; A. J. Romanowsky; M. J. West; Y. Schuberth

    2007-09-23T23:59:59.000Z

    Context:Struble (1988) found what appeared to be a cD halo without cD galaxy in the center of the galaxy cluster Abell 545. This remarkable feature has been passed almost unnoticed for nearly twenty years. Aims:Our goal is to review Struble's claim by providing a first (preliminary) photometric and spectroscopic analysis of this ''star pile''. Methods:Based on archival VLT-images and long-slit spectra obtained with Gemini-GMOS, we describe the photometric structure and measure the redshift of the star pile and of the central galaxy. Results:The star pile is indeed associated with Abell 545. Its velocity is higher by about 1300 km/s than that of the central object. The spectra indicate an old, presumably metal-rich population. Its brightness profile is much shallower than that of typical cD-galaxies. Conclusions:The formation history and the dynamical status of the star pile remain elusive, until high S/N spectra and a dynamical analysis of the galaxy cluster itself become available. We suggest that the star pile might provide an interesting test of the Cold Dark Matter paradigm.

  2. Hypervelocity Stars. I. The Spectroscopic Survey

    E-Print Network [OSTI]

    Warren R. Brown; Margaret J. Geller; Scott J. Kenyon; Michael J. Kurtz

    2006-04-13T23:59:59.000Z

    We discuss our targeted search for hypervelocity stars (HVSs), stars traveling with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Our survey, now half complete, has successfully identified a total of four probable HVSs plus a number of other unusual objects. Here we report the most recently discovered two HVSs: SDSS J110557.45+093439.5 and possibly SDSS J113312.12+010824, traveling with Galactic rest-frame velocities at least +508+-12 and +418+-10 km/s, respectively. The other late B-type objects in our survey are consistent with a population of post main-sequence stars or blue stragglers in the Galactic halo, with mean metallicity [Fe/H]=-1.3 and velocity dispersion 108+-5 km/s. Interestingly, the velocity distribution shows a tail of objects with large positive velocities that may be a mix of low-velocity HVSs and high-velocity runaway stars. Our survey also includes a number of DA white dwarfs with unusually red colors, possibly extremely low mass objects. Two of our objects are B supergiants in the Leo A dwarf, providing the first spectroscopic evidence for star formation in this dwarf galaxy within the last ~30 Myr.

  3. Quasiuniversal properties of neutron star mergers

    E-Print Network [OSTI]

    Sebastiano Bernuzzi; Alessandro Nagar; Simone Balmelli; Tim Dietrich; Maximiliano Ujevic

    2014-06-06T23:59:59.000Z

    Binary neutron star mergers are studied using nonlinear 3+1 numerical relativity simulations and the analytical effective-one-body (EOB) model. The EOB model predicts quasiuniversal relations between the mass-rescaled gravitational wave frequency and the binding energy at the moment of merger, and certain dimensionless binary tidal coupling constants depending on the stars Love numbers, compactnesses and the binary mass ratio. These relations are quasiuniversal in the sense that, for a given value of the tidal coupling constant, they depend significantly neither on the equation of state nor on the mass ratio, though they do depend on stars spins. The spin dependence is approximately linear for small spins aligned with the orbital angular momentum. The quasiuniversality is a property of the conservative dynamics; nontrivial relations emerge as the binary interaction becomes tidally dominated. This analytical prediction is qualitatively consistent with new, multi-orbit numerical relativity results for the relevant case of equal-mass irrotational binaries. Universal relations are thus expected to characterize neutron star mergers dynamics. In the context of gravitational wave astronomy, these universal relations may be used to constrain the neutron star equation of state using waveforms that model the merger accurately.

  4. Quark Matter, Massive Stars and Strange Planets

    E-Print Network [OSTI]

    F. Weber; Ch. Schaab; M. K. Weigel; N. K. Glendenning

    1996-04-09T23:59:59.000Z

    This paper gives an overview of the properties of all possible equilibrium sequences of compact strange-matter stars with nuclear crusts, which range from strange stars to strange dwarfs. In contrast to their non-strange counterparts, --neutron stars and white dwarfs--, their properties are determined by two (rather than one) parameters, the central star density and the density at the base of the nuclear crust. This leads to stellar strange-matter configurations whose properties are much more complex than those of the conventional sequence. As an example, two generically different categories of stable strange dwarfs are found, which could be the observed white dwarfs. Furthermore we find very low-mass strange stellar objects, with masses as small as those of Jupiter or even lighter planets. Such objects, if abundant enough in our Galaxy, should be seen by the presently performed gravitational microlensing searches. Further aspects studied in this paper concern the limiting rotational periods and the cooling behavior of neutron stars and their strange counterparts.

  5. 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.

  6. Strange Quark Matter and Compact Stars

    E-Print Network [OSTI]

    Fridolin Weber

    2004-09-27T23:59:59.000Z

    Astrophysicists distinguish between three different types of compact stars. These are white dwarfs, neutron stars, and black holes. The former contain matter in one of the densest forms found in the Universe which, together with the unprecedented progress in observational astronomy, make such stars superb astrophysical laboratories for a broad range of most striking physical phenomena. These range from nuclear processes on the stellar surface to processes in electron degenerate matter at subnuclear densities to boson condensates and the existence of new states of baryonic matter--like color superconducting quark matter--at supernuclear densities. More than that, according to the strange matter hypothesis strange quark matter could be more stable than nuclear matter, in which case neutron stars should be largely composed of pure quark matter possibly enveloped in thin nuclear crusts. Another remarkable implication of the hypothesis is the possible existence of a new class of white dwarfs. This article aims at giving an overview of all these striking physical possibilities, with an emphasis on the astrophysical phenomenology of strange quark matter. Possible observational signatures associated with the theoretically proposed states of matter inside compact stars are discussed as well. They will provide most valuable information about the phase diagram of superdense nuclear matter at high baryon number density but low temperature, which is not accessible to relativistic heavy ion collision experiments.

  7. Neutron Stars Opacity and Proton Fraction

    E-Print Network [OSTI]

    P. N. Alcain; C. O. Dorso

    2015-02-03T23:59:59.000Z

    Background: In neutron stars the nucleons are submitted to extreme conditions. The study of this natural occurring objects can lead to further understanding of the behaviour of nuclear matter in highly asymmetric nuclei. Among the characteristics of neutron stars, its neutrino absorption - associated to structural inhomoegeneities - stands out as one of the possible magnitudes linked to an observable. Purpose: We have carried out a systematic study of this neutrino absorption for different thermodynamic conditions in order to assess the impact that the structure has on it. Method: We study the dynamics of nucleons in conditions according to the neutron star crust with a semiclassical molecular dynamics model, for different densities, proton fractions and temperature, we calculate the long range opacity and the cluster distribution. Results: The neutrino absorption, the main mechanism for neutron stars cooldown, takes its highest value for temperatures and densities low compared with the inner crust, and a proton fraction is close to the symmetric case $x=0.5$. Conclusions: Within the used model the neutrinos are absorbed mostly close to the surface of the neutron star. Also, for high temperatures, a large cluster still exists, but the appearance of several small-sized clusters smears out the very long range order needed for neutrino absorption.

  8. Thermonuclear Burning on Rapidly Accreting Neutron Stars

    E-Print Network [OSTI]

    Lars Bildsten

    1997-09-10T23:59:59.000Z

    Neutron stars in mass-transferring binaries are accreting the hydrogen and helium rich matter from the surfaces of their companions. This article simply explains the physics associated with how that material eventually fuses to form heavier nuclei and the observations of the time dependent phenomena (such as Type I X-ray bursts) associated with the thermally unstable thermonuclear reactions. We explain how the outcome depends on the composition of the accreting matter, the accretion rate and the mass, radius and thermal state of the neutron star. We also introduce many new analytic relations that are convenient for comparisons to both observations and computational results. After explaining nuclear burning for spherically symmetric accretion onto neutron stars, we discuss the possibility of asymmetric burning. In particular, we discuss some of the mysteries from EXOSAT observations of Type I X-Ray bursts and how the solution to these puzzles may lie in considering the lateral propagation of nuclear burning fronts around the star. Fully understanding this problem requires knowledge of parameters previously neglected such as the distribution of fresh fuel on the star, the magnetic field strength, and the stellar rotation. Recent RXTE observations of bursters may finally tell us some of these parameters.

  9. Color superconducting quark matter in compact stars

    E-Print Network [OSTI]

    D. B. Blaschke; T. Klahn; F. Sandin

    2007-12-02T23:59:59.000Z

    Recent indications for high neutron star masses (M \\sim 2 M_sun) and large radii (R > 12 km) could rule out soft equations of state and have provoked a debate whether the occurence of quark matter in compact stars can be excluded as well. We show that modern quantum field theoretical approaches to quark matter including color superconductivity and a vector meanfield allow a microscopic description of hybrid stars which fulfill the new, strong constraints. For these objects color superconductivity turns out to be an essential ingredient for a successful description of the cooling phenomenology in accordance with recently developed tests. We discuss the energy release in the neutrino untrapping transition as a new aspect of the problem that hybrid stars masquerade themselves as neutron stars. Quark matter searches in future generations of low-temperature/high-density nucleus-nucleus collision experiments such as low-energy RHIC and CBM @ FAIR might face the same problem of an almost crossover behavior of the deconfinement transition. Therefore, diagnostic tools shall be derived from effects of color superconductivity.

  10. Long Island STEM Hub Community Advisory Council

    E-Print Network [OSTI]

    Homes, Christopher C.

    leveraging reports from the NYS Department of Labor, the LIA Chief Economist, etc., to identify the high to build STEM capabilities · Dowli

  11. The Hub of Innovation for American Housing

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

    15 | Building America eere.energy.gov 2. Choose Preferred Route Zero Energy Ready Homes Ultra-High Efficiency * Enclosure * Low-Load HVAC Speed Adoption by Lowering Risks of I...

  12. Critical Materials Hub | Department of Energy

    Office of Environmental Management (EM)

    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 for4,645 3,625 1,006 492 742 33 1112011AT&T, Inc.'sEnergyTexas1.SpaceFluorControlsEnergy Reaffirmed

  13. Energy Efficient Buildings Hub | 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 YouTube|6721 Federal RegisterHydrogenDistribution Technologies Issued: July

  14. Energy Efficient Buildings Hub | Department of Energy

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

    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 for4,645 3,625 1,006 492 742 33Frequently20,000 Russian NuclearandJunetrackEllen| Department ofBatteriesRecordEnergy

  15. EnergyHub | 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 being directedAnnual SiteofEvaluating A PotentialJump to:Emminol JumpEnergy SystemSystemsEconomicEnergyAi Jump

  16. Presentation: Hubs+ Report | Department of Energy

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

    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 for4,645 3,625 1,006 492 742Energy China 2015of 2005UNS Electric, Inc.DepartmentFleet Card

  17. Fuels From Sunlight Hub | Department of Energy

    Energy Savers [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 being directed off Energy.gov. Are you sure you want toworldPowerHome| Department ofForms Forms EngravingFreshFuels

  18. The Department of Energy's Energy Innovation Hubs

    Office of Environmental Management (EM)

    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 for4,645 3,625 1,006 492 742 33Frequently AskedEnergyIssuesEnergy Solar Decathlon2001 Power PlantAPRILTheDepartmentState

  19. Fuels From Sunlight Hub | 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.pdf Flash2006-52.pdf0.pdfDepartment ofEnergy 3 FuelModel | DepartmentFuels From

  20. Solent Enterprise Hub | 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 YouKizildere IRaghuraji Agro Industries Pvt LtdShawangunk, NewSingapore JumpSolarezo JumpSolarvestSolea ConsultingSolent

  1. The Hub of Innovation for American Housing

    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'tOriginEducationVideoStrategic| DepartmentDepartmentTheEnergy TheClean TheTheME111,

  2. Reading Enterprise Hub | 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 YouKizildere IRaghuraji Agro Industries Pvt Ltd Jump to: navigation, searchRay County, Missouri:ReSun Energy Pvt LtdReading

  3. SEAB Hubs+ Report | Department of Energy

    Office of Environmental Management (EM)

    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 for4,645 3,625 1,006 492 742 33Frequently AskedEnergy SmallImplementing theFinancingJERSEY PRINCETONWESTIdaho0 NorthSEABSEAB

  4. Botswana Innovation Hub | 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 being directedAnnual Siteof EnergyInnovation in CarbonofBiotinsBoston College Jump to: navigation,

  5. 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.

  6. Magnetized Atmospheres around Accreting Neutron Stars

    E-Print Network [OSTI]

    S. Zane; R. Turolla; A. Treves

    2000-02-01T23:59:59.000Z

    We present a detailed investigation of atmospheres around accreting neutron stars with high magnetic field ($B\\gtrsim 10^{12}$ G) and low luminosity ($L\\lesssim 10^{33}$ erg/s). We compute the atmospheric structure, intensity and emergent spectrum for a plane-parallel, pure hydrogen medium by solving the transfer equations for the normal modes coupled to the hydrostatic and energy balance equations. The hard tail found in previous investigations for accreting, non-magnetic neutron stars with comparable luminosity is suppressed and the X-ray spectrum, although still harder than a blackbody at the star effective temperature, is nearly planckian in shape. Spectra from accreting atmospheres, both with high and low fields, are found to exhibit a significant excess at optical wavelengths above the Rayleigh-Jeans tail of the X-ray continuum.

  7. Torsional oscillations of nonbare strange stars

    E-Print Network [OSTI]

    Mannarelli, Massimo; Parisi, Alessandro; Pilo, Luigi; Tonelli, Francesco

    2015-01-01T23:59:59.000Z

    Strange stars are one of the possible compact stellar objects that can be formed after a supernova collapse. We consider a model of strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting layer. These two phases constitute the {\\it quarksphere}, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming a ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming a few hundreds Fermi thick electron layer separating the ionic crust from the underlying quark matter. The ionic matter and the crystalline color superconducting matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fra...

  8. Evolution of Close Neutron Star Binaries

    E-Print Network [OSTI]

    W. Ogawaguchi; Y. Kojima

    1996-10-17T23:59:59.000Z

    We have calculated evolution of neutron star binaries towards the coalescence driven by gravitational radiation. The hydrodynamical effects as well as the general relativistic effects are important in the final phase. All corrections up to post$^{2.5}$-Newtonian order and the tidal effect are included in the orbital motion. The star is approximated by a simple Newtonian stellar model called affine star model. Stellar spins and angular momentum are assumed to be aligned. We have showed how the internal stellar structure affects the stellar deformation, variations of the spins, and the orbital motion of the binary just before the contact. The gravitational wave forms from the last a few revolutions significantly depend on the stellar structure.

  9. SED modeling of Young Massive Stars

    E-Print Network [OSTI]

    Thomas P. Robitaille

    2007-11-27T23:59:59.000Z

    In this contribution, I review the applications and potential limitations of the spectral energy distribution fitting tool that I have developed, with a strong emphasis on the limits to which this tool can be used to improve our understanding of massive star formation. I discuss why our current grid of models cannot be used to distinguish between the several competing theories of massive star formation. I also discuss stellar mass determinations, artificial correlations between parameters in the grid of models, multiplicity, confusion, dust assumptions, and unique fits. I briefly review the improvements we intend to carry out for our next grid of models, which will eliminate many of these limitations. Finally, I show examples of applications of this tool to massive young stars.

  10. Main sequence stars with asymmetric dark matter

    E-Print Network [OSTI]

    Fabio Iocco; Marco Taoso; Florent Leclercq; Georges Meynet

    2012-01-25T23:59:59.000Z

    We study the effects of feebly or non-annihilating weakly interacting Dark Matter (DM) particles on stars that live in DM environments denser than that of our Sun. We find that the energy transport mechanism induced by DM particles can produce unusual conditions in the core of Main Sequence stars, with effects which can potentially be used to probe DM properties. We find that solar mass stars placed in DM densities of rhochi>= e2 GeV/cm3 are sensitive to Spin-Dependent scattering cross-section sigmsd >= e-37 cm2 and a DM particle mass as low as mchi=5 GeV, accessing a parameter range weakly constrained by current direct detection experiments.

  11. A new method to derive star formation histories of galaxies from their star cluster distributions

    E-Print Network [OSTI]

    Thomas Maschberger; Pavel Kroupa

    2007-05-07T23:59:59.000Z

    Star formation happens in a clustered way which is why the star cluster population of a particular galaxy is closely related to the star formation history of this galaxy. From the probabilistic nature of a mass function follows that the mass of the most-massive cluster of a complete population, M_max, has a distribution with the total mass of the population as a parameter. The total mass of the population is connected to the star formation rate (SFR) by the length of a formation epoch. Since due to evolutionary effects only massive star clusters are observable up to high ages it is convenient to use this M_max(SFR) relation for the reconstruction of a star formation history. The age-distribution of the most-massive clusters can therefore be used to constrain the star formation history of a galaxy. The method, including an assessment of the inherent uncertainties, is introduced with this contribution, while following papers will apply this method to a number of galaxies.

  12. Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars

    E-Print Network [OSTI]

    Wako Aoki; Timothy C. Beers; Norbert Christlieb; John E. Norris; Sean G. Ryan; Stelios Tsangarides

    2006-09-26T23:59:59.000Z

    The chemical compositions of 26 metal-poor stars that exhibit strong CH and/or C2 molecular bands are determined based on high-resolution spectroscopy. We define carbon-enhanced stars taking account of the carbon abundance ratio ([C/Fe]) and the evolutionary status. Twenty two stars in our sample satisfy our modified definition for Carbon-Enhanced Metal-Poor (CEMP) stars. In addition, we measure Na abundances for nine other carbon-enhanced stars for which abundances of other elements have been previously reported. Combining our new sample with the results of previous work, we investigate the abundance and evolutionary status of a total of 64 CEMP stars. In this paper, we separate the carbon-enhanced objects into Ba-rich and Ba-normal objects, and discuss on (1) the metallicity distributions, (2) the correlation between Ba and C (and C+N) abundances, (3) C abundance distributions, (3) the distributions of evolutionary status, and (5) Na abundances. The implications of these results on the origins of carbon in CEMP stars are discussed.

  13. LANL/Green Star spectrometer tests

    SciTech Connect (OSTI)

    Sampson, T.E.; Cremers, T.L.; Vo, D.T. [Los Alamos National Lab., NM (United States); Seldiakov, Y.P.; Dorin, A.B.; Kondrashov, M.V. [Green Star, Moscow (Russian Federation); Timoshin, V.I. [VNIINM, Moscow (Russian Federation)

    1997-12-01T23:59:59.000Z

    The US and Russia have agreed to the joint development of a nondestructive assay system for use to support the dismantlement of nuclear weapons in Russia. This nondestructive assay system will be used to measure plutonium produced by the conversion of Russian nuclear weapons. The NDA system for Russia will be patterned after the ARIES NDA system being constructed at Los Alamos. One goal of the program is to produce an NDA system for use in Russia that maximizes the use of Russian resources to facilitate maintenance and future upgrades. The Green Star SBS50 Single Board Spectrometer system (Green Star Ltd., Moscow, Russia) has been suggested for use as the data acquisition component for gamma ray instruments in the system. Possible uses are for plutonium isotopic analysis and also segmented gamma scanning. Green Star has also developed analysis software for the SBS50. This software, both plutonium isotopic analysis and uranium enrichment analysis, was developed specifically for customs/border inspection applications (low counting rate applications and identification as opposed to quantification) and was not intended for MC and A applications. Because of the relative immaturity of the Green Star plutonium isotopic analysis software (it has been under development for only one year and is patterned after US development circa 1980), it was tentatively agreed, before the tests, that the Russian NDA system would use the Los Alamos PC/FRAM software for plutonium isotopic analysis. However, it was also decided to include the Green Star plutonium isotopic software in the testing, both to quantify its performance for MC and A applications and also to provide additional data to Green Star for further development of their software. The main purpose of the testing was to evaluate the SBS-50 spectrometer as a data acquisition device for use with LANL software.

  14. Axion Stars in the Infrared Limit

    E-Print Network [OSTI]

    Joshua Eby; Peter Suranyi; Cenalo Vaz; L. C. R. Wijewardhana

    2015-02-06T23:59:59.000Z

    Following Ruffini and Bonazzola, we use a quantized boson field to describe condensates of axions forming compact objects. Without substantial modifications, the method can only be applied to axions with decay constant, $f_a$, satisfying $\\delta=(f_a\\,/\\,M_P)^2\\ll 1$, where $M_P$ is the Planck mass. Similarly, the applicability of the Ruffini-Bonazzola method to axion stars also requires that the relative binding energy of axions satisfies $\\Delta=\\sqrt{1-(E_a\\,/\\,m_a)^2}\\ll1$, where $E_a$ and $m_a$ are the energy and mass of the axion. The simultaneous expansion of the equations of motion in $\\delta$ and $\\Delta$ leads to a simplified set of equations, depending only on the parameter, $\\lambda=\\sqrt{\\delta}\\,/\\,\\Delta$ in leading order of the expansions. Keeping leading order in $\\Delta$ is equivalent to the infrared limit, in which only relevant and marginal terms contribute to the equations of motion. The number of axions in the star is uniquely determined by $\\lambda$. Numerical solutions are found in a wide range of $\\lambda$. At small $\\lambda$ the mass and radius of the axion star rise linearly with $\\lambda$. While at larger $\\lambda$ the radius of the star continues to rise, the mass of the star, $M$, attains a maximum at $\\lambda_{\\rm max}\\simeq 0.58$. All stars are unstable for $\\lambda>\\lambda_{\\rm max}$ . We discuss the relationship of our results to current observational constraints on dark matter and the phenomenology of Fast Radio Bursts.

  15. PRECISE DOPPLER MONITORING OF BARNARD'S STAR

    SciTech Connect (OSTI)

    Choi, Jieun; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)] [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); McCarthy, Chris [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States)] [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Fischer, Debra A. [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States)] [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Johnson, John A. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)] [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Wright, Jason T., E-mail: jieun_eb@berkeley.edu [Department of Astronomy, The Pennsylvania State University, University Park, PA 16802 (United States)

    2013-02-20T23:59:59.000Z

    We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during the 25 years between 1987 and 2012. The early precision was 20 m s{sup -1} but was 2 m s{sup -1} during the last 8 years, constituting the most extensive and sensitive search for Doppler signatures of planets around this stellar neighbor. We carefully analyze the 136 Keck radial velocities spanning 8 years by first applying a periodogram analysis to search for nearly circular orbits. We find no significant periodic Doppler signals with amplitudes above {approx}2 m s{sup -1}, setting firm upper limits on the minimum mass (Msin i) of any planets with orbital periods from 0.1 to 1000 days. Using a Monte Carlo analysis for circular orbits, we determine that planetary companions to Barnard's Star with masses above 2 M {sub Circled-Plus} and periods below 10 days would have been detected. Planets with periods up to 2 years and masses above 10 M {sub Circled-Plus} (0.03 M {sub Jup}) are also ruled out. A similar analysis allowing for eccentric orbits yields comparable mass limits. The habitable zone of Barnard's Star appears to be devoid of roughly Earth-mass planets or larger, save for face-on orbits. Previous claims of planets around the star by van de Kamp are strongly refuted. The radial velocity of Barnard's Star increases with time at 4.515 {+-} 0.002 m s{sup -1} yr{sup -1}, consistent with the predicted geometrical effect, secular acceleration, that exchanges transverse for radial components of velocity.

  16. Beryllium in Disk and Halo Stars -- Evidence for a Beryllium Dispersion in Old Stars

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Megan C. Novicki

    2005-12-13T23:59:59.000Z

    The study of Be in stars of differing metal content can elucidate the formation mechanisms and the Galactic chemical evolution of Be. We have obtained high-resolution, high signal-to-noise spectra of the resonance lines of Be II in eight stars with the high-dispersion spectrograph (HDS) on the Subaru 8.2 m telescope on Mauna Kea. Abundances of Be have been determined through spectrum synthesis. The stars with [Fe/H] values > -1.1 conform to the published general trend of Be vs Fe. We have confirmed the high Be abundance in HD 94028 and have found a similarly high Be abundance in another star, HD 132475, at the same metallicity: [Fe/H] = -1.5. These two stars are 0.5 - 0.6 dex higher in Be than the Be-Fe trend. While that general trend contains the evidence for a Galaxy-wide enrichment in Be and Fe, the higher Be abundances in those two stars indicates local Be enrichments. Possible enrichment mechanisms include hypernovae and multiple supernova explosions contained in a superbubble. The star G 64-37 has [Fe/] = -3.2; we have determined its Be abundance to look for evidence of a Be plateau. It's Be abundance appears to extend the Be-Fe trend to lower Fe abundances without any evidence for a plateau as had been indicated by a high Be abundance in another very metal-poor star, G 64-12. Although these two stars have similar Be abundances within the errors, it could be that their different Be values may be indicating that a Be dispersion exists even at the lowest metallicities.

  17. Effective No-Hair Relations for Neutron Stars and Quark Stars: Relativistic Results

    E-Print Network [OSTI]

    Kent Yagi; Koutarou Kyutoku; George Pappas; Nicolas Yunes; Theocharis A. Apostolatos

    2014-09-08T23:59:59.000Z

    Astrophysical charge-free black holes are known to satisfy no-hair relations through which all multipole moments can be specified in terms of just their mass and spin angular momentum. We here investigate the possible existence of no-hair-like relations among multipole moments for neutron stars and quark stars that are independent of their equation of state. We calculate the multipole moments of these stars up to hexadecapole order by constructing uniformly-rotating and unmagnetized stellar solutions to the Einstein equations. For slowly-rotating stars, we construct stellar solutions to quartic order in spin in a slow-rotation expansion, while for rapidly-rotating stars, we solve the Einstein equations numerically with the LORENE and RNS codes. We find that the multipole moments extracted from these numerical solutions are consistent with each other. We confirm that the current-dipole is related to the mass-quadrupole in an approximately equation of state independent fashion, which does not break for rapidly rotating neutron stars or quark stars. We further find that the current-octupole and the mass-hexadecapole moments are related to the mass-quadrupole in an approximately equation of state independent way to $\\sim 10%$, worsening in the hexadecapole case. All of our findings are in good agreement with previous work that considered stellar solutions to leading-order in a weak-field expansion. The quartic in spin, slowly-rotating solutions found here allow us to estimate the systematic errors in the measurement of the neutron star's mass and radius with future X-ray observations, such as NICER and LOFT. We find that the effect of these quartic-in-spin terms on the quadrupole and hexadecapole moments and stellar eccentricity may dominate the error budget for very rapidly-rotating neutron stars. The new universal relations found here should help to reduce such systematic errors.

  18. A planet orbiting the star Gliese 86

    E-Print Network [OSTI]

    D. Queloz; M. Mayor; L. Weber; A. Blecha; M. Burnet; B. Confino; D. Naef; F. Pepe; N. Santos; S. Udry

    1999-10-12T23:59:59.000Z

    A 4MJ planet with a 15.8day orbital period has been detected from very precise radial velocity measurements with the CORALIE echelle spectrograph. A second remote and more massive companion has also been detected. All the planetary companions so far detected in orbit closer than 0.08 AU have a parent star with a statistically higher metal content compared to the metallicity distribution of other stars with planets. Different processes occuring during their formation may provide a possible explanation for this observation.

  19. On the First Generation of Stars

    E-Print Network [OSTI]

    Joseph Silk; Mathieu Langer

    2006-06-12T23:59:59.000Z

    We argue that the first stars may have spanned the conventional mass range rather than be identified with the Very Massive Objects (100-1000 solar masses) favoured by numerical simulations. Specifically, we find that magnetic field generation processes acting in the first protostellar systems suffice to produce fields that exceed the threshold for MRI instability to operate and thereby allow the MRI dynamo to generate equipartition-amplitude magnetic fields on protostellar mass scales below 50 solar masses. Such fields allow primordial star formation to occur at essentially any metallicity by regulating angular momentum transfer, fragmentation, accretion and feedback in much the same way as occurs in conventional molecular clouds.

  20. Heavy flavor production in the STAR experiment

    E-Print Network [OSTI]

    Barbara Trzeciak; for the STAR Collaboration

    2014-09-11T23:59:59.000Z

    In this paper, recent STAR heavy flavor measurements in proton-proton and heavy-ion collisions are highlighted. We report studies of open charm mesons, reconstructed directly from hadronic decay products, and studies of electrons from semi-leptonic decays of heavy flavor hadrons. We also present J/$\\psi$ measurements via the di-electron decay channel at various collision systems and energies. In Au+Au collisions the energy dependence of J/$\\psi$ production measured at $\\sqrt{s_{NN}}$ = 39, 62.4 and 200 GeV is shown. Finally, prospects of heavy flavor measurements with the STAR detector upgrades are discussed.

  1. Conversion of neutron stars to strange stars as the central engine of gamma-ray bursts

    E-Print Network [OSTI]

    Ignazio Bombaci; Bhaskar Datta

    2000-01-27T23:59:59.000Z

    We study the conversion of a neutron star to a strange star as a possible energy source for gamma-ray bursts. We use different recent models for the equation of state of neutron star matter and strange quark matter. We show that the total amount of energy liberated in the conversion is in the range of (1-4) 10^{53} ergs (one order of magnitude larger than previous estimates) and is in agreement with the energy required to power gamma-ray burst sources at cosmological distances.

  2. Gamma-Ray Bursts and Afterglows from Rotating Strange Stars and Neutron Stars

    E-Print Network [OSTI]

    Z. G. Dai; T. Lu

    1998-10-21T23:59:59.000Z

    We here discuss a new model of $\\gamma$-ray bursts (GRBs) based on differentially rotating strange stars. Strange stars in this model and differentially rotating neutron stars in the Klu\\'zniak-Ruderman model can produce extremely relativistic, variable fireballs required by GRBs and then become millisecond pulsars. The effect of such pulsars on expansion of the postburst fireballs through magnetic dipole radiation is studied. We show that these two models can explain naturally not only various features of GRBs but also light curves of afterglows.

  3. Making information flow explicit in HiStar

    E-Print Network [OSTI]

    Zeldovich, Nickolai

    HiStar is a new operating system designed to minimize the amount of code that must be trusted. HiStar provides strict information flow control, which allows users to specify precise data security policies without unduly ...

  4. Advanced Combustion Modeling with STAR-CD using Transient Flemelet...

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

    Modeling with STAR-CD using Transient Flemelet Models: TIF and TPV Advanced Combustion Modeling with STAR-CD using Transient Flemelet Models: TIF and TPV Presentation given at the...

  5. Hitting the Target: ENERGY STAR® SSL Outdoor Area Lighting Webcast

    Broader source: Energy.gov [DOE]

    In this October 8, 2009 webcast, ENERGY STAR Program Manager Richard Karney gave an overview of ENERGY STAR criteria covering SSL-based outdoor area and roadway lighting, outdoor wall packs,...

  6. Probing young massive clusters with laser guide star adaptive optics

    E-Print Network [OSTI]

    McCrady, Nate

    2009-01-01T23:59:59.000Z

    laser guide star adaptive optics Nate McCrady Received: 10laser guide star adaptive optics (LGS/AO) on the 10 m Keckof 4 Mpc. Our adaptive optics work is motivated by three

  7. Neutron stars and strong-field effects of general relativity

    E-Print Network [OSTI]

    W. Kluzniak

    2000-12-29T23:59:59.000Z

    The basic observed properties of neutron stars are reviewed. I suggest that neutron stars in low-mass X-ray binaries are the best of all known sites for testing strong-field effects of general relativity.

  8. Grant County PUD- EnergyStar New Home Certification Program

    Broader source: Energy.gov [DOE]

    Grant County PUD offers incentives to qualifying customers through the Energy Star Home Certification Program. The Energy Star certification is available for both new site-built homes and new...

  9. ENERGY STAR Residential Water Heaters to Save Americans Up to...

    Energy Savers [EERE]

    ENERGY STAR Residential Water Heaters to Save Americans Up to 823 Million in the Next Five Years ENERGY STAR Residential Water Heaters to Save Americans Up to 823 Million in the...

  10. On star formation rate and turbulent dissipation in galactic models

    E-Print Network [OSTI]

    E. P. Kurbatov

    2007-12-10T23:59:59.000Z

    The models of star formation function and of dissipation of turbulent energy of interstellar medium are proposed. In star formation model the feedback of supernovae is taken into account. It is shown that hierarchical scenario of galaxy formation with proposed models is able to explain the observable star formation pause in the Galaxy.

  11. Transition density and pressure in hot neutron stars

    E-Print Network [OSTI]

    Xu, Jun; Chen, Lie-Wen; Ko, Che Ming; Li, Bao-An.

    2010-01-01T23:59:59.000Z

    in neutrino-trapped neutron stars than in neutrino-free neutron stars. Furthermore, both are found to decrease with increasing temperature of a neutron star as well as increasing slope parameter of the nuclear symmetry energy, except that the transition...

  12. Planet-Star Plasma Interactions and Possible Radio Emission

    E-Print Network [OSTI]

    Demoulin, Pascal

    ? · Planetary radio emissions properties & energy source in Planet-Star plasma interactions · Scaling laws contraints on scaling laws & internal structure models Comparative magnetospheric physics (star-planet properties & energy source in Planet-Star plasma interactions · Scaling laws and Extrapolation to hot

  13. Creating an intelligent agent for StarCraft: Brood War

    E-Print Network [OSTI]

    Ernst, Damien

    Creating an intelligent agent for StarCraft: Brood War University of Ličge Faculty of Applied artificialintelligence (AI)? Video games Why real-time strategy (RTS) games? Introduction #12;StarCraft: Brood War a patrol unit #12;Implementation Chapter III #12;StarCraft is not open source! The Brood War Application

  14. ENERGY STAR Back-To-School Shopping Checklist

    E-Print Network [OSTI]

    ENERGY STAR® Back-To-School Shopping Checklist Students can make a difference by shopping "smart" with ENERGY STAR® . Computing the Savings ENERGY STAR Qualified Computer Equipment Computer Monitor ENERGY up to 90 percent more energy than standard monitors. Printer If every home office were powered

  15. THE Be STAR SPECTRA (BeSS) DATABASE

    SciTech Connect (OSTI)

    Neiner, C.; De Batz, B. [LESIA, UMR 8109 du CNRS, Observatoire de Paris, UPMC, Univ. Paris Diderot, 92195 Meudon Cedex (France); Cochard, F. [Shelyak Instruments, Les Roussets, 38420 Revel (France); Floquet, M.; Mekkas, A. [GEPI, UMR 8111 du CNRS, Observatoire de Paris, Univ. Paris Diderot, 92195 Meudon Cedex (France); Desnoux, V., E-mail: coralie.neiner@obspm.fr [ARAS, Astronomical Ring for Access to Spectroscopy (Country Unknown)

    2011-11-15T23:59:59.000Z

    Be stars vary on many timescales, from hours to decades. A long time base of observations to analyze certain phenomena in these stars is therefore necessary. Collecting all existing and future Be star spectra into one database has thus emerged as an important tool for the Be star community. Moreover, for statistical studies, it is useful to have centralized information on all known Be stars via an up-to-date catalog. These two goals are what the Be Star Spectra (BeSS, http://basebe.obspm.fr) database proposes to achieve. The database contains an as-complete-as-possible catalog of known Be stars with stellar parameters, as well as spectra of Be stars from all origins (any wavelength, any epoch, any resolution, etc.). It currently contains over 54,000 spectra of more than 600 different Be stars among the {approx}2000 Be stars in the catalog. A user can access and query this database to retrieve information on Be stars or spectra. Registered members can also upload spectra to enrich the database. Spectra obtained by professional as well as amateur astronomers are individually validated in terms of format and science before being included in BeSS. In this paper, we present the database itself as well as examples of the use of BeSS data in terms of statistics and the study of individual stars.

  16. Energy star compliant voice over internet protocol (VoIP) telecommunications network including energy star compliant VoIP devices

    DOE Patents [OSTI]

    Kouchri, Farrokh Mohammadzadeh

    2012-11-06T23:59:59.000Z

    A Voice over Internet Protocol (VoIP) communications system, a method of managing a communications network in such a system and a program product therefore. The system/network includes an ENERGY STAR (E-star) aware softswitch and E-star compliant communications devices at system endpoints. The E-star aware softswitch allows E-star compliant communications devices to enter and remain in power saving mode. The E-star aware softswitch spools messages and forwards only selected messages (e.g., calls) to the devices in power saving mode. When the E-star compliant communications devices exit power saving mode, the E-star aware softswitch forwards spooled messages.

  17. A CATALOG OF GALACTIC INFRARED CARBON STARS

    SciTech Connect (OSTI)

    Chen, P. S. [National Astronomical Observatories/Yunnan Observatory and Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011 (China); Yang, X. H., E-mail: iraspsc@yahoo.com.cn, E-mail: yangxh@cqu.edu.cn [Department of Physics, Chongqing University, Chongqing 400044 (China)

    2012-02-15T23:59:59.000Z

    We collected almost all of the Galactic infrared carbon stars (IRCSs) from literature published up to the present to organize a catalog of 974 Galactic IRCSs in this paper. Some of their photometric properties in the near-, mid-, and far-infrared are discussed.

  18. Singularity-free dark energy star

    E-Print Network [OSTI]

    Farook Rahaman; Anil Kumar Yadav; Saibal Ray; Raju Maulick; Ranjan Sharma

    2011-08-25T23:59:59.000Z

    We propose a model for an anisotropic dark energy star where we assume that the radial pressure exerted on the system due to the presence of dark energy is proportional to the isotropic perfect fluid matter density. We discuss various physical features of our model and show that the model satisfies all the regularity conditions and stable as well as singularity-free.

  19. Attenuation of Beaming Oscillations Near Neutron Stars

    E-Print Network [OSTI]

    M. Coleman Miller

    2000-07-17T23:59:59.000Z

    Observations with RXTE have revealed kilohertz quasi-periodic brightness oscillations (QPOs) from nearly twenty different neutron-star low-mass X-ray binaries (LMXBs). These frequencies often appear as a pair of kilohertz QPOs in a given power density spectrum. In many models the higher-frequency of these QPOs is a beaming oscillation at the frequency of a nearly circular orbit at some radius near the neutron star. In such models it is expected that there will also be beaming oscillations at the stellar spin frequency and at overtones of the orbital frequency, but no strong QPOs have been detected at these frequencies. We therefore examine the processes that can attenuate beaming oscillations near neutron stars, and in doing so extend the work on this subject that was initiated by the discovery of lower-frequency QPOs from LMXBs. Among our main results are (1)in a spherical scattering cloud, all overtones of rotationally modulated beaming oscillations are attenuated strongly, not just the even harmonics, and (2)it is possible to have a relatively high-amplitude modulation near the star at, e.g., the stellar spin frequency, even if no peak at that frequency is detectable in a power density spectrum taken at infinity. We discuss the application of these results to modeling of kilohertz QPOs.

  20. 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 ...

  1. Eddington Capture Sphere around luminous stars

    E-Print Network [OSTI]

    Adam Stahl; Maciek Wielgus; Marek Abramowicz; W?odek Klu?niak; Wenfei Yu

    2012-08-10T23:59:59.000Z

    Test particles infalling from infinity onto a compact spherical star with a mildly super-Eddington luminosity at its surface are typically trapped on the "Eddington Capture Sphere" and do not reach the surface of the star. The presence of a sphere on which radiation pressure balances gravity for static particles was first discovered some twenty five years ago. Subsequently, it was shown to be a capture sphere for particles in radial motion, and more recently also for particles in non-radial motion, in which the Poynting-Robertson radiation drag efficiently removes the orbital angular momentum of the particles, reducing it to zero. Here we develop this idea further, showing that "levitation" on the Eddington sphere (above the stellar surface) is a state of stable equilibrium, and discuss its implications for Hoyle-Lyttleton accretion onto a luminous star. When the Eddington sphere is present, the cross-section of a compact star for actual accretion is typically less than the geometrical cross-section (pi Rsquared), direct infall onto the stellar surface only being possible for relativistic particles, with the required minimum particle velocity at infinity typically ~1/2 the speed of light. We further show that particles on typical trajectories in the vicinity of the stellar surface will also be trapped on the Eddington Capture Sphere.

  2. Predictions from 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)

    2010-03-15T23:59:59.000Z

    We compute trivariate probability distributions in the landscape, scanning simultaneously over the cosmological constant, the primordial density contrast, and spatial curvature. We consider two different measures for regulating the divergences of eternal inflation, and three different models for observers. In one model, observers are assumed to arise in proportion to the entropy produced by stars; in the others, they arise at a fixed time (5 or 10x10{sup 9} years) after star formation. The star formation rate, which underlies all our observer models, depends sensitively on the three scanning parameters. We employ a recently developed model of star formation in the multiverse, a considerable refinement over previous treatments of the astrophysical and cosmological properties of different pocket universes. For each combination of observer model and measure, we display all single and bivariate probability distributions, both with the remaining parameter(s) held fixed and marginalized. Our results depend only weakly on the observer model but more strongly on the measure. Using the causal diamond measure, the observed parameter values (or bounds) lie within the central 2{sigma} of nearly all probability distributions we compute, and always within 3{sigma}. This success is encouraging and rather nontrivial, considering the large size and dimension of the parameter space. The causal patch measure gives similar results as long as curvature is negligible. If curvature dominates, the causal patch leads to a novel runaway: it prefers a negative value of the cosmological constant, with the smallest magnitude available in the landscape.

  3. Predictions from Star Formation in the Multiverse

    E-Print Network [OSTI]

    Raphael Bousso; Stefan Leichenauer

    2009-07-28T23:59:59.000Z

    We compute trivariate probability distributions in the landscape, scanning simultaneously over the cosmological constant, the primordial density contrast, and spatial curvature. We consider two different measures for regulating the divergences of eternal inflation, and three different models for observers. In one model, observers are assumed to arise in proportion to the entropy produced by stars; in the others, they arise at a fixed time (5 or 10 billion years) after star formation. The star formation rate, which underlies all our observer models, depends sensitively on the three scanning parameters. We employ a recently developed model of star formation in the multiverse, a considerable refinement over previous treatments of the astrophysical and cosmological properties of different pocket universes. For each combination of observer model and measure, we display all single and bivariate probability distributions, both with the remaining parameter(s) held fixed, and marginalized. Our results depend only weakly on the observer model but more strongly on the measure. Using the causal diamond measure, the observed parameter values (or bounds) lie within the central $2\\sigma$ of nearly all probability distributions we compute, and always within $3\\sigma$. This success is encouraging and rather nontrivial, considering the large size and dimension of the parameter space. The causal patch measure gives similar results as long as curvature is negligible. If curvature dominates, the causal patch leads to a novel runaway: it prefers a negative value of the cosmological constant, with the smallest magnitude available in the landscape.

  4. Solid Waste Diversion Plan Fallen Star, 2012

    E-Print Network [OSTI]

    Aluwihare, Lihini

    Solid Waste Diversion Plan DO HO DUH Fallen Star, 2012 Stuart Collection UC San Diego Updated July 2012 Prepared by: Facilities Management #12;UC San Diego Solid Waste Diversion Plan Table of Contents Overview Location and Areas Covered Recycling and Solid Waste Management Contact Campus/Medical Center

  5. Constraints in the coupling Star-Life

    E-Print Network [OSTI]

    L. Sertorio; G. Tinetti

    2001-10-01T23:59:59.000Z

    If life is sustained by a process of photosynthesis, not necessarily the same existing on Earth, the surface temperature of the star and the orbit of the host planet cannot be whatsoever. In fact the global life cycle, no matter how complicated, must contain in general an upper photochemical branch and a lower dark branch, characterized by a higher and a lower temperature. These two temperatures are star-orbit related. The velocity along the cycle or, in other words, the power of the life machine, depends in general on several other parameters. First of all the Gibbs photon availability, which is a star-orbit parameter and is the input for the upper branch. Then follows the energy cascade that develops along the organic web with a large number of interactions and typical times that must match the typical times generated by the combination of spin value and orientation, eccentricity and precession. Finally, the capacity of the web to keep the global life cycle running along the life span of the star, comes from some inner form of self-endurance and self-balance. The property of not being transient could be the right way of introducing the concept of intelligent life.

  6. Light curves from rapidly rotating neutron stars

    E-Print Network [OSTI]

    Numata, Kazutoshi

    2010-01-01T23:59:59.000Z

    We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account of relativistic effects such as the Doppler boost due to the rapid rotation and light bending assuming the Schwarzschild metric around the neutron star. We assume that the core $r$-modes penetrate to the surface fluid ocean to have sufficiently large amplitudes to disturb the spot. For a $l'=m$ core $r$-mode, the oscillation frequency $\\omega\\approx2m\\Omega/[l'(l'+1)]$ defined in the co-rotating frame of the star will be detected by a distant observer, where $l'$ and $m$ are respectively the spherical harmonic degree and the azimuthal wave number of the mode, and $\\Omega$ is the spin frequency of the star. In a linear theory of oscillation, using a parameter $A$ we parametrize the mode amplitudes such that ${\\rm max}\\left(|\\xi_\\theta|,|\\xi_\\phi|\\right)/R=A$ at the surface, w...

  7. Life Extinction Due To Neutron Star Mergers

    E-Print Network [OSTI]

    Arnon Dar; Ari Laor; Nir J. Shaviv

    1996-11-24T23:59:59.000Z

    Cosmic ray bursts (CRBs) from mergers or accretion induced collapse of neutron stars that hit an Earth-like planet closer than $\\sim 1 kpc$ from the explosion produce lethal fluxes of atmospheric muons at ground level, underground and underwater. These CRBs also destroy the ozone layer and radioactivate the environment. The mean rate of such life devastating CRBs is one in 100 million years (Myr), consistent with the observed 5 ``great'' extinctions in the past 600 Myr. Unlike the previously suggested extraterrestrial extinction mechanisms the CRBs explain massive life extinction on the ground, underground and underwater and the higher survival levels of radiation resistant species and of terrain sheltered species. More distant mergers can cause smaller extinctions. Biological mutations caused by ionizing radiation produced by the CRB may explain a fast appearance of new species after mass extinctions. The CRB extinction predicts detectable enrichment of rock layers which formed during the extinction periods with cosmogenically produced radioactive nucleides such as $^{129}$I, $^{146}$Sm, $^{205}$Pb with and $^{244}$Pu. Tracks of high energy particles in rock layers on Earth and on the moon may also contain records of intense CRBs. An early warning of future extinctions due to neutron star mergers can be obtained by identifying, mapping and timing all the nearby binary neutron stars systems. A final warning of an approaching CRB from a nearby neutron stars merger will be provided by a gamma ray burst a few days before the arrival of the CRB.

  8. Quantum Vacuum Instability Near Rotating Stars

    E-Print Network [OSTI]

    A L Matacz; A C Ottewill; P C W Davies

    1992-12-08T23:59:59.000Z

    We discuss the Starobinskii-Unruh process for the Kerr black hole. We show how this effect is related to the theory of squeezed states. We then consider a simple model for a highly relativistic rotating star and show that the Starobinskii-Unruh effect is absent.

  9. Technetium and the third dredge up in AGB stars II. Bulge stars

    E-Print Network [OSTI]

    Stefan Uttenthaler; Josef Hron; Thomas Lebzelter; Maurizio Busso; Mathias Schultheis; Hans Ulrich Kaeufl

    2006-10-17T23:59:59.000Z

    We searched for Technetium (Tc) in a sample of bright oxygen-rich asymptotic giant branch (AGB) stars located in the outer galactic bulge. Tc is an unstable element synthesised via the s-process in deep layers of AGB stars, thus it is a reliable indicator of both recent s-process activity and third dredge-up. We aim to test theoretical predictions on the luminosity limit for the onset of third dredge-up. Using high resolution optical spectra obtained with the UVES spectrograph at ESO's VLT we search for resonance lines of neutral Tc in the blue spectral region of our sample stars. These measurements allow us to improve the procedure of classification of stars with respect to their Tc content by using flux ratios. Synthetic spectra based on MARCS atmospheric models are presented and compared to the observed spectra around three lines of Tc. Bolometric magnitudes are calculated based on near infrared photometry of the objects. Among the sample of 27 long period bulge variables four were found to definitely contain Tc in their atmospheres. The luminosity of the Tc rich stars is in agreement with predictions from AGB evolutionary models on the minimum luminosity at the time when third dredge-up sets in. However, AGB evolutionary models and a bulge consisting of a single old population cannot be brought into agreement. This probably means that a younger population is present in the bulge, as suggested by various authors, which contains the Tc-rich stars here identified.

  10. Gamma Ray Bursts from delayed collapse of neutron stars to quark matter stars

    E-Print Network [OSTI]

    Z. Berezhiani; I. Bombaci; A. Drago; F. Frontera; A. Lavagno

    2003-02-13T23:59:59.000Z

    We propose a model to explain how a Gamma Rays Burst can take place days or years after a supernova explosion. Our model is based on the conversion of a pure hadronic star (neutron star) into a star made at least in part of deconfined quark matter. The conversion process can be delayed if the surface tension at the interface between hadronic and deconfined-quark-matter phases is taken into account. The nucleation time (i.e. the time to form a critical-size drop of quark matter) can be extremely long if the mass of the star is small. Via mass accretion the nucleation time can be dramaticaly reduced and the star is finally converted into the stable configuration. A huge amount of energy, of the order of 10$^{52}$--10$^{53}$ erg, is released during the conversion process and can produce a powerful Gamma Ray Burst. The delay between the supernova explosion generating the metastable neutron star and the new collapse can explain the delay proposed in GRB990705 and in GRB011211.

  11. Gamma Ray Bursts from delayed collapse of neutron stars to quark matter stars

    E-Print Network [OSTI]

    Berezhiani, Z G; Drago, A; Frontera, F; Lavagno, A

    2003-01-01T23:59:59.000Z

    We propose a model to explain how a Gamma Rays Burst can take place days or years after a supernova explosion. Our model is based on the conversion of a pure hadronic star (neutron star) into a star made at least in part of deconfined quark matter. The conversion process can be delayed if the surface tension at the interface between hadronic and deconfined-quark-matter phases is taken into account. The nucleation time (i.e. the time to form a critical-size drop of quark matter) can be extremely long if the mass of the star is small. Via mass accretion the nucleation time can be dramaticaly reduced and the star is finally converted into the stable configuration. A huge amount of energy, of the order of 10$^{52}$--10$^{53}$ erg, is released during the conversion process and can produce a powerful Gamma Ray Burst. The delay between the supernova explosion generating the metastable neutron star and the new collapse can explain the delay proposed in GRB990705 and in GRB011211.

  12. LIMITING ACCRETION ONTO MASSIVE STARS BY FRAGMENTATION-INDUCED STARVATION

    SciTech Connect (OSTI)

    Peters, Thomas; Klessen, Ralf S.; Banerjee, Robi [Institut fuer Theoretische Astrophysik, Zentrum fuer Astronomie der Universitaet Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Low, Mordecai-Mark Mac, E-mail: thomas.peters@ita.uni-heidelberg.d [Department of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024-5192 (United States)

    2010-12-10T23:59:59.000Z

    Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly understood. Two widely discussed models are monolithic collapse of molecular cloud cores and competitive accretion. To learn more about massive star formation, we perform and analyze simulations of the collapse of rotating, massive, cloud cores including radiative heating by both non-ionizing and ionizing radiation using the FLASH adaptive-mesh refinement code. These simulations show fragmentation from gravitational instability in the enormously dense accretion flows required to build up massive stars. Secondary stars form rapidly in these flows and accrete mass that would have otherwise been consumed by the massive star in the center, in a process that we term fragmentation-induced starvation. This explains why massive stars are usually found as members of high-order stellar systems that themselves belong to large clusters containing stars of all masses. The radiative heating does not prevent fragmentation, but does lead to a higher Jeans mass, resulting in fewer and more massive stars than would form without the heating. This mechanism reproduces the observed relation between the total stellar mass in the cluster and the mass of the largest star. It predicts strong clumping and filamentary structure in the center of collapsing cores, as has recently been observed. We speculate that a similar mechanism will act during primordial star formation.

  13. Limiting Accretion onto Massive Stars by Fragmentation-Induced Starvation

    SciTech Connect (OSTI)

    Peters, Thomas; /ZAH, Heidelberg; Klessen, Ralf S.; /ZAH, Heidelberg /KIPAC, Menlo Park; Mac Low, Mordecai-Mark; /Amer. Museum Natural Hist.; Banerjee, Robi; /ZAH, Heidelberg

    2010-08-25T23:59:59.000Z

    Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly understood. Two widely discussed models are monolithic collapse of molecular cloud cores and competitive accretion. To learn more about massive star formation, we perform simulations of the collapse of rotating, massive, cloud cores including radiative heating by both non-ionizing and ionizing radiation using the FLASH adaptive mesh refinement code. These simulations show fragmentation from gravitational instability in the enormously dense accretion flows required to build up massive stars. Secondary stars form rapidly in these flows and accrete mass that would have otherwise been consumed by the massive star in the center, in a process that we term fragmentation-induced starvation. This explains why massive stars are usually found as members of high-order stellar systems that themselves belong to large clusters containing stars of all masses. The radiative heating does not prevent fragmentation, but does lead to a higher Jeans mass, resulting in fewer and more massive stars than would form without the heating. This mechanism reproduces the observed relation between the total stellar mass in the cluster and the mass of the largest star. It predicts strong clumping and filamentary structure in the center of collapsing cores, as has recently been observed. We speculate that a similar mechanism will act during primordial star formation.

  14. Laser Guide Star Adaptive Optics without Tip-tilt

    E-Print Network [OSTI]

    R. Davies; S. Rabien; C. Lidman; M. Le Louarn; M. Kasper; N. M. Forster Schreiber; V. Roccatagliata; N. Ageorges; P. Amico; C. Dumas; F. Mannucci

    2008-01-24T23:59:59.000Z

    Adaptive optics (AO) systems allow a telescope to reach its diffraction limit at near infrared wavelengths. But to achieve this, a bright natural guide star (NGS) is needed for the wavefront sensing, severely limiting the fraction of the sky over which AO can be used. To some extent this can be overcome with a laser guide star (LGS). While the laser can be pointed anywhere in the sky, one still needs to have a natural star, albeit fainter, reasonably close to correct the image motion (tip-tilt) to which laser guide stars are insensitive. There are in fact many astronomical targets without suitable tip-tilt stars, but for which the enhanced resolution obtained with the Laser Guide Star Facility (LGSF) would still be very beneficial. This article explores what adaptive optics performance one might expect if one dispenses with the tip-tilt star, and in what situations this mode of observing might be needed.

  15. The MACHO Project LMC Variable Star Inventory; 4, Multimode RR Lyrae Stars, Distance to the LMC and Age of the Oldest Stars

    E-Print Network [OSTI]

    Alcock, C B; Alves, D R; Axelrod, T S; Becker, A C; Bennett, D P; Cook, K H; Freeman, K C; Griest, K; Guern, J A; Lehner, M J; Marshall, S L; Minniti, D; Peterson, B A; Pratt, M R; Quinn, P J; Rodgers, A W; Sutherland, W; Welch, D L

    1996-01-01T23:59:59.000Z

    We report the discovery of 73 double-mode RR Lyrae (RRd) stars in fields near the bar of the LMC. The stars are detected among the MACHO database of short-period variables that currently contains about 7900 RR Lyrae stars. Fundamental periods (P_0) for these stars are found in the range 0.46-0.55 days and first overtone-to-fundamental period ratios are found to be in the range 0.742 FBE) of the instability strip. Comparison of the calibrated MACHO V and R_KC photometry with these derived absolute magnitudes yields an absorption-corrected distan...

  16. Constraining the neutron star equation of state with gravitational wave signals from coalescing binary neutron stars

    E-Print Network [OSTI]

    Michalis Agathos; Jeroen Meidam; Walter Del Pozzo; Tjonnie G. F. Li; Marco Tompitak; John Veitch; Salvatore Vitale; Chris Van Den Broeck

    2015-03-18T23:59:59.000Z

    Recently exploratory studies were performed on the possibility of constraining the neutron star equation of state (EOS) using signals from coalescing binary neutron stars, or neutron star-black hole systems, as they will be seen in upcoming advanced gravitational wave detectors such as Advanced LIGO and Advanced Virgo. In particular, it was estimated to what extent the combined information from multiple detections would enable one to distinguish between different equations of state through hypothesis ranking or parameter estimation. Under the assumption of zero neutron star spins both in signals and in template waveforms and considering tidal effects to 1PN order, it was found that O(20) sources would suffice to distinguish between a hard, moderate, and soft equation of state. Here we revisit these results, this time including neutron star tidal effects to the highest order currently known, termination of gravitational waveforms at the contact frequency, neutron star spins, and the resulting quadrupole-monopole interaction. We also take the masses of neutron stars in simulated sources to be distributed according to a relatively strongly peaked Gaussian, as hinted at by observations, but without assuming that the data analyst will necessarily have accurate knowledge of this distribution for use as a mass prior. We find that especially the effect of the latter is dramatic, necessitating many more detections to distinguish between different EOS and causing systematic biases in parameter estimation, on top of biases due to imperfect understanding of the signal model pointed out in earlier work. This would get mitigated if reliable prior information about the mass distribution could be folded into the analyses.

  17. The APM Survey for Cool Carbon Stars in the Galactic Halo - II The Search for Dwarf Carbon Stars

    E-Print Network [OSTI]

    E. J. Totten; M. J. Irwin; P. A. Whitelock

    2000-01-07T23:59:59.000Z

    We present proper motion measurements for carbon stars found during the APM Survey for Cool Carbon Stars in the Galactic Halo (Totten & Irwin, 1998). Measurements are obtained using a combination of POSSI, POSSII and UKST survey plates supplemented where necessary by CCD frames taken at the Isaac Newton Telescope. We find no significant proper motion for any of the new APM colour-selected carbon stars and so conclude that there are no dwarf carbon stars present within this sample. We also present proper motion measurements for three previously known dwarf carbon stars and demonstrate that these measurements agree favourably with those previously quoted in the literature, verifying our method of determining proper motions. Results from a complimentary program of JHK photometry obtained at the South African Astronomical Observatory are also presented. Dwarf carbon stars are believed to have anomalous near-infrared colours, and this feature is used for further investigation of the nature of the APM carbon stars. Our results support the use of JHK photomtery as a dwarf/giant discriminator and also reinforce the conclusion that none of the new APM-selected carbon stars are dwarfs. Finally, proper motion measurements combined with extant JHK photometry are presented for a sample of previously known Halo carbon stars, suggesting that one of these stars, CLS29, is likely to be a previously unrecognised dwarf carbon star.

  18. WZ Sagittae as a DQ Herculis star

    E-Print Network [OSTI]

    Jean-Pierre Lasota; Erik Kuulkers; Phil Charles

    1999-01-21T23:59:59.000Z

    We argue that quiescent WZ Sge is a rapidly spinning magnetic rotator in which most of the matter transfered from the secondary is ejected from the system. Assuming that the observed 27.87 s oscillation period is due to the spinning white dwarf we propose that the other observed principal period of 28.96 s is a beat due to reprocessing of the rotating white dwarf beam on plasma blobs in Keplerian rotation at the outer disc rim. The weaker, transient, 29.69 s period is identified as a beat with the Keplerian period of the magnetosphere. WZ Sge evolves through a cycle of spin-up and spin-down phases. During the spin-down phase it is a DQ Her star, during the spin-up phase it should be a ER UMa star.

  19. NLTE wind models for SMC stars

    E-Print Network [OSTI]

    Jiri Krticka

    2005-09-15T23:59:59.000Z

    We study stellar wind properties of selected late O stars in the Small Magellanic Cloud (SMC). We calculate NLTE line-driven wind models for these stars and compare predicted wind parameters with observed values. We found satisfactory agreement between theoretical and observed terminal velocities. On the other hand, predicted and observed mass-loss rates are in a good agreement only for higher mass-loss rates. For mass-loss rates lower than approximately 10^{-7} M_sun / year we found large discrepancy between theoretical and observed values. We propose a new explanation of this effect based on dynamical decoupling of some atoms. Finally, we study the dependence of wind terminal velocities and mass-loss rates on metallicity.

  20. Northern JHK Standard Stars for Array Detectors

    E-Print Network [OSTI]

    L. K. Hunt; F. Mannucci; L. Testi; S. Migliorini; R. M. Stanga; C. Baffa; F. Lisi; L. Vanzi

    1999-10-22T23:59:59.000Z

    We report J, H and K photometry of 86 stars in 40 fields in the northern hemisphere. The fields are smaller than or comparable to a 4x4 arcmin field-of-view, and are roughly uniformly distributed over the sky, making them suitable for a homogeneous broadband calibration network for near-infrared panoramic detectors. K magnitudes range from 8.5 to 14, and J-K colors from -0.1 to 1.2. The photometry is derived from a total of 3899 reduced images; each star has been measured, on average, 26.0 times per filter on 5.5 nights. Typical errors on the photometry are about 0.012.

  1. A SECOND NEUTRON STAR IN M4?

    SciTech Connect (OSTI)

    Kaluzny, J.; Rozanska, A.; Rozyczka, M.; Krzeminski, W. [Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw (Poland); Thompson, Ian B. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2012-05-01T23:59:59.000Z

    We show that the optical counterpart of the X-ray source CX 1 in M4 is a {approx}20th magnitude star, located in the color-magnitude diagram on (or very close to) the main sequence of the cluster, and exhibiting sinusoidal variations of the flux. We find the X-ray flux to be also periodically variable, with X-ray and optical minima coinciding. Stability of the optical light curve, lack of UV-excess, and unrealistic mean density resulting from period-density relation for semidetached systems speak against the original identification of CX 1 as a cataclysmic variable. We argue that the X-ray active component of this system is a neutron star (probably a millisecond pulsar).

  2. 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.

  3. Singularity free anisotropic strange quintessence star

    E-Print Network [OSTI]

    Piyali Bhar

    2014-11-29T23:59:59.000Z

    Present paper provides a new model of anisotropic strange star corresponding to the exterior schwarzschild metric. The Einstein field equations have been solved by utilizing the Krori Barua (KB) ansatz in presence of quintessence field characterized by a parameter omegaq . The obtained solutions are free from central singularity. Our model is potentially stable.The numerical values of mass of the different strange stars SAXJ1808.4-3658(SS1)(radius=7.07 km),4U1820- 30 (radius=10 km),Vela X-12 (radius=9.99 km),PSR J 1614-2230 (radius=10.3 km) obtained from our model is very close to the observational data that confirms the validity of our proposed model. The interior solution is also matched to the exterior Schwarzschild spacetime in presence of thin shell where negative surface pressure is required to hold the thin shell against collapse.

  4. On neutron star/supernova remnant associations

    E-Print Network [OSTI]

    V. V. Gvaramadze

    2001-04-01T23:59:59.000Z

    It is pointed out that a cavity supernova (SN) explosion of a moving massive star could result in a significant offset of the neutron star (NS) birth-place from the geometrical centre of the supernova remnant (SNR). Therefore: a) the high implied transverse velocities of a number of NSs (e.g. PSR B1610-50, PSR B1757-24, SGR0525-66) could be reduced; b) the proper motion vector of a NS should not necessarily point away from the geometrical centre of the associated SNR; c) the circle of possible NS/SNR associations could be enlarged. An observational test is discussed, which could allow to find the true birth-places of NSs associated with middle-aged SNRs, and thereby to get more reliable estimates of their transverse velocities.

  5. Reconstructing the Star Formation Histories of Galaxies

    E-Print Network [OSTI]

    Uta Fritze; Thomas Lilly

    2007-01-15T23:59:59.000Z

    We present a methodological study to find out how far back and to what precision star formation histories of galaxies can be reconstructed from CMDs, from integrated spectra and Lick indices, and from integrated multi-band photometry. Our evolutionary synthesis models GALEV allow to describe the evolution of galaxies in terms of all three approaches and we have assumed typical observational uncertainties for each of them and then investigated to what extent and accuracy different star formation histories can be discriminated. For a field in the LMC bar region with both a deep CMD from HST observations and a trailing slit spectrum across exactly the same field of view we could test our modelling results against real data.

  6. 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.

  7. Magnetic Field Evolution in Superconducting Neutron Stars

    E-Print Network [OSTI]

    Graber, Vanessa; Glampedakis, Kostas; Lander, Samuel K

    2015-01-01T23:59:59.000Z

    The presence of superconducting and superfluid components in the core of mature neutron stars calls for the rethinking of a number of key magnetohydrodynamical notions like resistivity, the induction equation, magnetic energy and flux-freezing. Using a multi-fluid magnetohydrodynamics formalism, we investigate how the magnetic field evolution is modified when neutron star matter is composed of superfluid neutrons, type-II superconducting protons and relativistic electrons. As an application of this framework, we derive an induction equation where the resistive coupling originates from the mutual friction between the electrons and the vortex/fluxtube arrays of the neutron and proton condensates. The resulting induction equation allows the identification of two timescales that are significantly different from those of standard magnetohydrodynamics. The astrophysical implications of these results are briefly discussed.

  8. 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.

  9. 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.

  10. Role of Hyperons in Neutron Stars

    E-Print Network [OSTI]

    J. R. Stone; P. A. M. Guichon; A. W. Thomas

    2010-12-14T23:59:59.000Z

    The latest observation of a Shapiro delay of the binary millisecond pulsar J1614-2230 by Demorest et al. Nature 467 1081 (2010) yielded the pulsar gravitational mass to be 1.97 +/- 0.04 solar mass, the heaviest observed pulsar to-date. This result produces a stringent constraint on Equation(s) of State (EoS) of high density neutron star matter. One of the main conclusions of Demorest et al. was that their result makes the presence of non-nucleonic components in the neutron star matter unlikely. We compare the result with our recent work and conclude that hyperons in high-density matter are fully consistent with the observation and that their presence is a necessary consequence of general physical laws.

  11. Entanglement Entropy of Magnetic Electron Stars

    E-Print Network [OSTI]

    Tameem Albash; Clifford V. Johnson; Scott MacDonald

    2015-04-08T23:59:59.000Z

    We study the behavior of the entanglement entropy in $(2+1)$--dimensional strongly coupled theories via the AdS/CFT correspondence. We consider theories at a finite charge density with a magnetic field, with their holographic dual being Einstein-Maxwell-Dilaton theory in four dimensional anti--de Sitter gravity. Restricting to black hole and electron star solutions at zero temperature in the presence of a background magnetic field, we compute their holographic entanglement entropy using the Ryu-Takayanagi prescription for both strip and disk geometries. In the case of the electric or magnetic zero temperature black holes, we are able to confirm that the entanglement entropy is invariant under electric-magnetic duality. In the case of the electron star with a finite magnetic field, for the strip geometry, we find a discontinuity in the first derivative of the entanglement entropy as the strip width is increased.

  12. Superbubble Activity in Star-Forming Galaxies

    E-Print Network [OSTI]

    M. S. Oey

    2002-12-03T23:59:59.000Z

    Mechanical feedback from massive stars, primarily from supernovae, can dominate ISM structuring and phase balance, thereby profoundly affecting galactic evolutionary processes. Our understanding of mechanical feedback is based on the adiabatic, wind-driven bubble model, applied on size scales ranging over three decades. Tests of the model, and our consequent understanding of feedback, are reviewed. While the model is broadly successful, critical unknowns still prevent a comprehensive understanding of the consequences of feedback.

  13. Energy Star Concepts for Highway Vehicles

    SciTech Connect (OSTI)

    Greene, D.L.

    2003-06-24T23:59:59.000Z

    The authors of this report, under the sponsorship of the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Weatherization and Intergovernmental Program, have investigated the possible application of Energy Star ratings to passenger cars and light trucks. This study establishes a framework for formulating and evaluating Energy Star rating methods that is comprised of energy- and environmental-based metrics, potential vehicle classification systems, vehicle technology factors, and vehicle selection criteria. The study tests several concepts and Energy Star rating methods using model-year 2000 vehicle data--a spreadsheet model has been developed to facilitate these analyses. This study tests two primary types of rating systems: (1) an outcome-based system that rates vehicles based on fuel economy, GHG emissions, and oil use and (2) a technology-based system that rates vehicles based on the energy-saving technologies they use. Rating methods were evaluated based on their ability to select vehicles with high fuel economy, low GHG emissions, and low oil use while preserving a full range of service (size and acceleration) and body style choice. This study concludes that an Energy Star rating for passenger cars and light trucks is feasible and that several methods could be used to achieve reasonable tradeoffs between low energy use and emissions and diversity in size, performance, and body type. It also shows that methods that consider only fuel economy, GHG emissions, or oil use will not select a diverse mix of vehicles. Finally, analyses suggest that methods that encourage the use of technology only, may result in increases in acceleration power and weight rather than reductions in oil use and GHG emissions and improvements in fuel economy.

  14. Some simple models for quark stars

    E-Print Network [OSTI]

    S. D. Maharaj; J. M. Sunzu; S. Ray

    2014-12-28T23:59:59.000Z

    We find two new classes of exact solutions for the Einstein-Maxwell equations. The solutions are obtained by considering charged anisotropic matter with a linear equation of state consistent with quark stars. The field equations are integrated by specifying forms for the measure of anisotropy and a gravitational potential which are physically reasonable. The solutions found generalize the Mark-Harko model and the Komathiraj-Maharaj model. A graphical analysis indicates that the matter variables are well behaved.

  15. Neutron Stars in Supernova Remnants and Beyond

    E-Print Network [OSTI]

    V. V. Gvaramadze

    2002-12-26T23:59:59.000Z

    We discuss a concept of off-centred cavity supernova explosion as applied to neutron star/supernova remnant associations and show how this concept could be used to preclude the anti-humane decapitating the Duck (G5.4-1.2 + G5.27-0.9) and dismembering the Swan (Cygnus Loop), as well as to search for a stellar remnant associated with the supernova remnant RCW86.

  16. The Dark Energy Star and Stability analysis

    E-Print Network [OSTI]

    Piyali Bhar; Farook Rahaman

    2015-01-12T23:59:59.000Z

    We have proposed a new model of dark energy star consisting of five zones namely, solid core of constant energy density, the thin shell between core and interior, an inhomogeneous interior region with anisotropic pressures, thin shell and the exterior vacuum region. We have discussed various physical properties. The model satisfies all the physical requirements. The stability condition under small linear perturbation has also been discussed.

  17. Obscured clusters.I. GLIMPSE30 - Young Milky Way Star Cluster Hosting Wolf-Rayet Stars

    E-Print Network [OSTI]

    Kurtev, R; Georgiev, L; Ortolani, S; Ivanov, V D

    2007-01-01T23:59:59.000Z

    Young massive clusters are perfect astrophysical laboratories for study of massive stars. Clusters with Wolf-Rayet (WR) stars are of special importance, since this enables us to study a coeval WR population at a uniform metallicity and known age. GLIMPSE30 (G30) is one of them. The cluster is situated near the Galactic plane (l=298.756deg, b=-0.408deg) and we aimed to determine its physical parameters and to investigate its high-mass stellar content and especially WR stars. Our analysis is based on SOFI/NTT JsHKs imaging and low resolution (R~2000) spectroscopy of the brightest cluster members in the K atmospheric window. For the age determination we applied isochrone fits for MS and Pre-MS stars. We derived stellar parameters of the WR stars candidates using a full nonLTE modeling of the observed spectra. Using a variety of techniques we found that G30 is very young cluster, with age t~4Myr. The cluster is located in Carina spiral arm, it is deeply embedded in dust and suffers reddening of Av~10.5+-1.1mag. T...

  18. Nonlinear mode coupling in rotating stars and the r-mode instability in neutron stars

    E-Print Network [OSTI]

    A. Katrin Schenk; Phil Arras; Eanna E. Flanagan; Saul A. Teukolsky; Ira Wasserman

    2001-07-11T23:59:59.000Z

    We develop the formalism required to study the nonlinear interaction of modes in rotating Newtonian stars in the weakly nonlinear regime. The formalism simplifies and extends previous treatments. At linear order, we elucidate and extend slightly a formalism due to Schutz, show how to decompose a general motion of a rotating star into a sum over modes, and obtain uncoupled equations of motion for the mode amplitudes under the influence of an external force. Nonlinear effects are added perturbatively via three-mode couplings. We describe a new, efficient way to compute the coupling coefficients, to zeroth order in the stellar rotation rate, using spin-weighted spherical harmonics. We apply this formalism to derive some properties of the coupling coefficients relevant to the nonlinear interactions of unstable r-modes in neutron stars, postponing numerical integrations of the coupled equations of motion to a later paper. From an astrophysical viewpoint, the most interesting result of this paper is that many couplings of r-modes to other rotational modes (modes with zero frequencies in the non-rotating limit) are small: either they vanish altogether because of various selection rules, or they vanish to lowest order in the angular velocity. In zero-buoyancy stars, the coupling of three r-modes is forbidden entirely and the coupling of two r-modes to one hybrid rotational mode vanishes to zeroth order in rotation frequency. In incompressible stars, the coupling of any three rotational modes vanishes to zeroth order in rotation frequency.

  19. EXTENDED STAR FORMATION IN THE INTERMEDIATE-AGE LARGE MAGELLANIC CLOUD STAR CLUSTER NGC 2209

    SciTech Connect (OSTI)

    Keller, Stefan C.; Mackey, A. Dougal; Da Costa, Gary S. [Research School of Astronomy and Astrophysics, Australian National University, Canberra (Australia)

    2012-12-10T23:59:59.000Z

    We present observations of the 1 Gyr old star cluster NGC 2209 in the Large Magellanic Cloud made with the GMOS imager on the Gemini South Telescope. These observations show that the cluster exhibits a main-sequence turnoff that spans a broader range in luminosity than can be explained by a single-aged stellar population. This places NGC 2209 amongst a growing list of intermediate-age (1-3 Gyr) clusters that show evidence for extended or multiple epochs of star formation of between 50 and 460 Myr in extent. The extended main-sequence turnoff observed in NGC 2209 is a confirmation of the prediction in Keller et al. made on the basis of the cluster's large core radius. We propose that secondary star formation is a defining feature of the evolution of massive star clusters. Dissolution of lower mass clusters through evaporation results in only clusters that have experienced secondary star formation surviving for a Hubble time, thus providing a natural connection between the extended main-sequence turnoff phenomenon and the ubiquitous light-element abundance ranges seen in the ancient Galactic globular clusters.

  20. Eruptive Mass Loss in Very Massive Stars and Population III Stars

    E-Print Network [OSTI]

    Nathan Smith

    2006-07-24T23:59:59.000Z

    I discuss the role played by short-duration eruptive mass loss in the evolution of very massive stars. Giant eruptions of Luminous Blue Variables (LBVs) like the 19th century event of eta Carinae can remove large quantities of mass almost instantaneously, making them significant in stellar evolution. They can potentially remove much more mass from the star than line-driven winds, especially if stellar winds are highly clumped such that previous estimates of O star mass-loss rates need to be revised downward. When seen in other galaxies as ``supernova impostors'', these LBV eruptions typically last for less than a decade, and they can remove of order 10 Msun as indicated by massive nebulae around LBVs. Such extreme mass-loss rates cannot be driven by radiation pressure on spectral lines, because the lines will completely saturate during the events. Instead, these outbursts must either be continuum-driven super-Eddington winds or outright hydrodynamic explosions, both of which are insensitive to metallicity. As such, this eruptive mode of mass loss could also play a pivotal role in the evolution and ultimate fate of massive metal-poor stars in the early universe. If they occur in these Population III stars, such eruptions would also profoundly affect the chemical yield and types of remnants from early supernovae and hypernovae thought to be the origin of long gamma ray bursts.

  1. Pulsations of rapidly rotating stars: II. Realistic modelling for intermediate-mass stars

    E-Print Network [OSTI]

    Ouazzani, Rhita-Maria; Dupret, Marc-Antoine

    2015-01-01T23:59:59.000Z

    Very high precision seismic space missions such as CoRoT and Kepler provide the means for testing the modelling of transport processes in stellar interiors. For some stars, such as $\\delta$ Scuti $\\gamma$ Doradus and Be stars, for instance, the observed pulsation spectra are modified by rotation to such an extent that it prevents any fruitful interpretation. Our aim is to characterise acoustic pulsation spectra of realistic stellar models in order to be able to interpret asteroseismic data from such stars. The 2-dimensional oscillation code ACOR, which treats rotation in a non-perturbative manner, is used to study pulsation spectra of highly distorted evolved models of stars. 2D models of stars are obtained by a self-consistent method which distorts spherically averaged stellar models a posteriori, at any stage of evolution, and for any type of rotation law. Four types of modes are calculated in a very dense frequency spectrum, among which are island modes. The regularity of the island modes spectrum is confi...

  2. No-Hair Relations for Neutron Stars and Quark Stars: Relativistic Results

    E-Print Network [OSTI]

    Yagi, Kent; Pappas, George; Yunes, Nicolas; Apostolatos, Theocharis A

    2014-01-01T23:59:59.000Z

    Astrophysical charge-free black holes are known to satisfy no-hair relations through which all multipole moments can be specified in terms of just their mass and spin angular momentum. We here investigate the possible existence of no-hair-like relations among multipole moments for neutron stars and quark stars that are independent of their equation of state. We calculate the multipole moments of these stars up to hexadecapole order by constructing uniformly-rotating and unmagnetized stellar solutions to the Einstein equations. For slowly-rotating stars, we construct stellar solutions to quartic order in spin in a slow-rotation expansion, while for rapidly-rotating stars, we solve the Einstein equations numerically with the LORENE and RNS codes. We find that the multipole moments extracted from these numerical solutions are consistent with each other. We confirm that the current-dipole is related to the mass-quadrupole in an approximately equation of state independent fashion, which does not break for rapidly ...

  3. Varieties of Cotton for East Central Texas.

    E-Print Network [OSTI]

    Killough, D. T. (David Thornton); McNess, George Thomas

    1927-01-01T23:59:59.000Z

    . Variety Roberts Big Boll. . Truitt. ........... ......... Crowder. Mebane Triumph.. Cook ............ Peterkin. ......... ....... Lone Star. ........ Crenshaw. Cleveland Big Boll Durango ......... Source of Seed * N L Willett Seed CO: Augusta... Boykin, Mebane, Cliett, Kasch, Truitt, Lone Star, Rowden, and Acala, are well adapted to this section of the state. These higher-yielding varieties are characterized by medium- to large-sized bolls; by percentages of lint rang- ing from 33.1 to 39...

  4. Varieties of Cotton for the Blackland Region of Central Texas.

    E-Print Network [OSTI]

    Killough, D. T. (David Thornton); Dunlavy, Henry; Rea, H. E. (Homer Earl)

    1929-01-01T23:59:59.000Z

    .88 for Qualla, $42.32 for New Boykin, and $42.23 for Harper. The money value per acre of Acala, Anton, lllebane, Sunshine, Truitt, Lankart, and Lone Star was for each in the order named slightly lower than Harper, ranging from $41.60 for Acala to $37....92 for Lone Star. CONTENTS Introduction ....................................... ........................................ Weather Conditions ...................... Method of Conducting the Variety Tests. .................................. Classificat...

  5. Varieties of Cotton for Central East Texas.

    E-Print Network [OSTI]

    Morris, H. F. (Harry Forrest); McNess, George Thomas

    1928-01-01T23:59:59.000Z

    staple. Wannamaker-Cleveland was sec- ~nd in yield with a higher percentage of lint and a longer staple than Ferguson Roundnose. Mebane Triumph, 3latchless Big Boll, and Lone Star followed in the order named in yield of lint per acre. It is notice... us on Roundnose. .... Wannamaker-Cleveland. Mehane Triumph.. ......... ........ Matchless Big Boll. Lone Star. ................ Surecrop .................. ........... Union Bi Boll.. ........ ~levelanf~ig Boll. Webb...

  6. 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.

  7. Gravitational microlensing of stars with transiting planets

    E-Print Network [OSTI]

    Geraint F. Lewis

    2001-10-17T23:59:59.000Z

    If planetary systems are ubiquitous then a fraction of stars should possess a transiting planet when being microlensed. This paper presents a study of the influence of such planets on microlensing light curves. For the giant planets recently identified, the deviations in the light curve can be substantial, although the specifics of the perturbations are dependent upon the radius of the planet relative to that of the star, the location of the planet over the stellar surface and the orientation of the sweeping caustic. Given that the instantaneous probability of transiting hot-Jupiter like planets is small, less than a percent, and only a proportion of microlensing events exhibit caustic crossing events, the probability of detecting a transiting planet during a microlensing event is small, $\\sim10^{-6}$. However, a number of factors influencing this probability, such as the number of solar type star that possess planets, are uncertain, and the prospect of detecting transiting planets in future large catalogues of microlensing light curves may be viable. The results of this study also have bearing on the gravitational microlensing of spots on the stellar surface.

  8. Habitable planets around the star Gl 581?

    E-Print Network [OSTI]

    Franck Selsis; J. F. Kasting; B. Levrard; J. Paillet; I. Ribas; X. Delfosse

    2007-11-21T23:59:59.000Z

    Radial velocity surveys are now able to detect terrestrial planets at habitable distance from M-type stars. Recently, two planets with minimum masses below 10 Earth masses were reported in a triple system around the M-type star Gliese 581. Using results from atmospheric models and constraints from the evolution of Venus and Mars, we assess the habitability of planets Gl 581c and Gl 581d and we discuss the uncertainties affecting the habitable zone (HZ) boundaries determination. We provide simplified formulae to estimate the HZ limits that may be used to evaluate the astrobiological potential of terrestrial exoplanets that will hopefully be discovered in the near future. Planets Gl 581c and 'd' are near, but outside, what can be considered as the conservative HZ. Planet 'c' receives 30% more energy from its star than Venus from the Sun, with an increased radiative forcing caused by the spectral energy distribution of Gl 581. Its habitability cannot however be positively ruled out by theoretical models due to uncertainties affecting cloud properties. Irradiation conditions of planet 'd' are comparable with those of early Mars. Thanks to the warming effect of CO2-ice clouds planet 'd' might be a better candidate for the first exoplanet known to be potentially habitable. A mixture of various greenhouse gases could also maintain habitable conditions on this planet.

  9. Habitable planets around the star Gl 581?

    E-Print Network [OSTI]

    Selsis, Franck; Levrard, B; Paillet, J; Ribas, I; Delfosse, X

    2007-01-01T23:59:59.000Z

    Radial velocity surveys are now able to detect terrestrial planets at habitable distance from M-type stars. Recently, two planets with minimum masses below 10 Earth masses were reported in a triple system around the M-type star Gliese 581. Using results from atmospheric models and constraints from the evolution of Venus and Mars, we assess the habitability of planets Gl 581c and Gl 581d and we discuss the uncertainties affecting the habitable zone (HZ) boundaries determination. We provide simplified formulae to estimate the HZ limits that may be used to evaluate the astrobiological potential of terrestrial exoplanets that will hopefully be discovered in the near future. Planets Gl 581c and 'd' are near, but outside, what can be considered as the conservative HZ. Planet 'c' receives 30% more energy from its star than Venus from the Sun, with an increased radiative forcing caused by the spectral energy distribution of Gl 581. Its habitability cannot however be positively ruled out by theoretical models due to u...

  10. Torsional oscillations of nonbare strange stars

    E-Print Network [OSTI]

    Massimo Mannarelli; Giulia Pagliaroli; Alessandro Parisi; Luigi Pilo; Francesco Tonelli

    2015-04-28T23:59:59.000Z

    Strange stars are one of the possible compact stellar objects that can be formed after a supernova collapse. We consider a model of strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting layer. These two phases constitute the {\\it quarksphere}, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming a ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming a few hundreds Fermi thick electron layer separating the ionic crust from the underlying quark matter. The ionic matter and the crystalline color superconducting matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fraction larger than $10^{-4}$ of the energy of a Vela-like glitch is conveyed to a torsional oscillation, the ionic crust will likely break. The reason is that the very rigid and heavy crystalline color superconducting crust layer will absorb only a small fraction of the glitch energy, leading to a large amplitude torsional oscillation of the ionic crust.

  11. Highly integrated electronics for the star TPC

    SciTech Connect (OSTI)

    Arthur, A.A.; Bieser, F.; Hearn, W.; Kleinfelder, S.; Merrick, T.; Millaud, J.; Noggle, T.; Rai, G.; Ritter, H.G.; Wieman, H. [Lawrence Berkeley Laboratory, CA (United States)

    1991-12-31T23:59:59.000Z

    The concept for the STAR TPC front-end electronics is presented and the progress toward the development of a fully integrated solution is described. It is the goal of the R+D program to develop the complete electronics chain for the STAR central TPC detector at RHIC. It is obvious that solutions chosen e.g. for ALEPH are not adequate for the 150000 channels that need to be instrumented for readout. It will be necessary to perform all the signal processing, digitization and multiplexing directly on the detector in order to reduce per channel cost and the amount of cabling necessary to read out the information. We follow the approach chosen by the EOS TPC project, where the readout electronics on the detector consists of an integrated preamplifier, a hybrid shaping amplifier, an integrated switched capacitor array and a highly multiplexed ADC. The STAR electronics will be further integrated so that approximately 16 channels of the preamplifier, the shaper, the analog store and the ADC will be contained in two integrated circuits located directly on the pad plane.

  12. Star Formation Histories in the Local Group

    E-Print Network [OSTI]

    Thomas M. Brown

    2004-07-09T23:59:59.000Z

    Deep color magnitude diagrams extending to the main sequence provide the most direct measure of the detailed star formation history in a stellar population. With large investments of observing time, HST can obtain such data for populations out to 1 Mpc, but its field of view is extremely small in comparison to the size of Local Group galaxies. This limitation severely constrains our understanding of galaxy formation. For example, the largest galaxy in the Local Group, Andromeda, offers an ideal laboratory for studying the formation of large spiral galaxies, but the galaxy shows substructure on a variety of scales, presumably due to its violent merger history. Within its remaining lifetime, HST can only sample a few sight-lines through this complex galaxy. In contrast, a wide field imager could provide a map of Andromeda's halo, outer disk, and tidal streams, revealing the spatially-dependent star formation history in each structure. The same data would enable many secondary studies, such as the age variation in Andromeda's globular cluster system, gigantic samples of variable stars, and microlensing tracers of the galaxy's dark matter distribution.

  13. Intergalactic stars in the Fornax Cluster

    E-Print Network [OSTI]

    Tom Theuns; S. J. Warren

    1996-09-10T23:59:59.000Z

    We have identified ten candidate intergalactic planetary nebulae in the Fornax galaxy cluster. These objects were found during observations in 1992 and 1993 in three fields chosen well away from any Fornax galaxy at 15 arcmin, 30 arcmin, and 45 arcmin from the centre of Fornax. We used the usual method of blinking images taken in a narrow OIII filter, with images taken in an adjacent broad filter. The measured fluxes in the narrow, broad, and I bands are consistent with these unresolved objects being planetary nebulae immersed in an intergalactic population of stars. Such a population is expected to arise as a consequence of tidal encounters between galaxies, and our findings strengthen the case for the existence of such tidal debris. The confirmation of some or all of these ten candidates as planetary nebulae would imply that intergalactic stars constitute a substantial fraction of all the stars in Fornax, up to an estimated 40 per cent. Intergalactic planetary nebulae could prove useful in probing the underlying cluster potential, since they would be far more abundant than galaxies. We discuss possible contamination of the sample by emission-line galaxies, but conclude that planetary nebulae is the most likely identification for the detected objects. keywords: intergalactic medium-- galaxies: interactions -- planetary nebulae: general -- clusters: individual: Fornax

  14. Gravitational collapse of a susy star

    E-Print Network [OSTI]

    L. Clavelli

    2006-02-02T23:59:59.000Z

    The evidence for a positive vacuum energy in our universe suggests that we might be living in a false vacuum destined to ultimately decay to a true vacuum free of dark energy. At present the simplest example of such a universe is one that is exactly supersymmetric (susy). It is expected that the nucleation rate of critically sized susy bubbles will be enhanced in regions of high density such as in degenerate stars. The consequent release of energy stored in Pauli towers provides a possible model for gamma ray bursts. Whether or not all or any of the currently observed bursts are due to this mechanism, it is important to define the signatures of this susy phase transition. After such a burst, due to the lifting of degeneracy pressure, the star would be expected to collapse into a black hole even though its mass is below the Chandrasekhar limit. Previous studies have treated the star as fully releasing its stored energy before the collapse. In this article we make an initial investigation of the effects of the collapse during the gamma ray emission.

  15. Energy Star program benefits Con Edison

    SciTech Connect (OSTI)

    NONE

    1995-05-01T23:59:59.000Z

    Impressed with savings in energy costs achieved after upgrading the lighting and air conditioning systems at its Manhattan headquarters, Home Box Office (HBO) wanted to do more, James Flock, vice president for computer and office systems, contacted Con Edison Co. of New York in March 1991 to determine what the company could do to save money by reducing energy consumed by personal computers. Arthur Kressner, Con Edison Research and Development manager contacted industry organizations and manufacturers for advice, but was told only to shut off computers at night and on weekends. Kressner arranged a series of meetings with IBM and the Electric Power Research Institute (EPRI) to discuss the issue, then approached the U.S. Environmental Protection Agency (EPA), which was designing a program to promote the introduction and use of energy-efficient office equipment. In 1992, the EPA announced the Energy Star program for PCs, enabling manufacturers to display the Energy Star logo on machines meeting program criteria, including the ability to enter a sleep mode in which neither the computer nor monitor consume more than 30 W or electricity. Industry experts estimate national energy consumption by office equipment could double by the year 2000, but Energy Star equipment is expected to improve efficiency and help maintain electric loads.

  16. Neutron-capture nucleosynthesis in the first stars

    SciTech Connect (OSTI)

    Roederer, Ian U. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Preston, George W.; Thompson, Ian B.; Shectman, Stephen A. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Sneden, Christopher, E-mail: iur@umich.edu [Department of Astronomy, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712 (United States)

    2014-04-01T23:59:59.000Z

    Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars.

  17. Explosive Combustion of a Neutron Star into a Quark Star: the non-premixed scenario

    E-Print Network [OSTI]

    Ouyed, Rachid; Jaikumar, Prashanth

    2013-01-01T23:59:59.000Z

    We review aspects of the hydrodynamical combustion of nuclear matter to strange quark matter in a neutron star. Numerical studies on non-premixed combustion that consistently include hydrodynamical flows in a reactive-diffusive setup show that in 1D, the conversion (burning) front moves at sub-sonic speeds and stops short of converting the entire star to SQM, essentially due to advective forces. However, in the process, we also find that neutrino cooling of the interface causes it to wrinkle, laying a platform for a deflagrative-to-detonative transition (DDT). We outline progress on improvements in the burning code (Burn-UD: http://quarknova.ucalgary.ca/software/Burn-UD/) that will ultimately reveal the mechanism that can explode the outermost layers of even a dense compact object like a neutron star.

  18. Cooling of neutron stars and hybrid stars with a stiff hadronic EoS

    E-Print Network [OSTI]

    H. Grigorian; D. Blaschke; D. N. Voskresensky

    2015-03-16T23:59:59.000Z

    Within the "nuclear medium cooling" scenario of neutron stars all reliably known temperature - age data, including those of the central compact objects in the supernova remnants of Cassiopeia A and XMMU-J1732, can be comfortably explained by a set of cooling curves obtained by variation of the star mass within the range of typical observed masses. The recent measurements of the high masses of the pulsars PSR J1614-2230 and PSR J0348-0432 on the one hand, and of the low masses for PSR J0737-3039B and the companion of PSR J1756-2251 on the other, provide independent proof for the existence of neutron stars with masses in a broad range from $\\sim 1.2$ to 2 $M_\\odot$. The values $M>2 M_{\\odot}$ call for sufficiently stiff equations of state for neutron star matter. We investigate the response of the set of neutron star cooling curves to a stiffening of the nuclear equation of state so that maximum masses of about $2.4 M_\\odot$ would be accessible and to a deconfinement phase transition from such stiff nuclear matter in the outer core to color superconducting quark matter in the inner core. Without readjustment of cooling inputs the mass range required to cover all cooling data for the stiff DD2 equation of state should include masses of $2.426 M_\\odot$ for describing the fast cooling of CasA while the existence of a quark matter core accelerates the cooling so that CasA cooling data are described with a hybrid star of mass $1.674 M_\\odot$.

  19. X-ray aurora in neutron star magnetospheres

    E-Print Network [OSTI]

    Vahid Rezania; John C. Samson; Peter Dobias

    2004-03-27T23:59:59.000Z

    In this study we propose a new generic model for QPOs based on oscillation modes of neutron star magnetospheres. We argue that the interaction of the accretion disk with the magnetosphere can excite resonant shear Alfven waves in a region of enhanced density gradients. We demonstrate that depending on the distance of this enhanced density region from the star and the magnetic field strength, the frequency of the field line resonance can range from several Hz (weaker field, farther from star), to approximately kHz frequencies (stronger field, ~ 2-10 star radii from the star). We show that such oscillations are able to significantly modulate inflow of matter from the high density region toward the star surface, and possibly produce the observed X-ray spectrum. In addition, we show that the observed 2:3 frequency ratio of QPOs is a natural result of our model.

  20. Dark matter transport properties and rapidly rotating neutron stars

    E-Print Network [OSTI]

    C. J. Horowitz

    2012-05-16T23:59:59.000Z

    Neutron stars are attractive places to look for dark matter because their high densities allow repeated interactions. Weakly interacting massive particles (WIMPs) may scatter efficiently in the core or in the crust of a neutron star. In this paper we focus on WIMP contributions to transport properties, such as shear viscosity or thermal conductivity, because these can be greatly enhanced by long mean free paths. We speculate that WIMPs increase the shear viscosity of neutron star matter and help stabilize r-mode oscillations. These are collective oscillations where the restoring force is the Coriolis force. At present r-modes are thought to be unstable in many observed rapidly rotating stars. If WIMPs stabilize the r-modes, this would allow neutron stars to spin rapidly. This likely requires WIMP-nucleon cross sections near present experimental limits and an appropriate density of WIMPs in neutron stars.

  1. HgMn Stars as apparent X-ray emitters

    E-Print Network [OSTI]

    Hubrig, S; Mathys, G

    1998-01-01T23:59:59.000Z

    In the ROSAT all-sky survey 11 HgMn stars were detected as soft X-ray emitters (Berghoefer, Schmitt & Cassinelli 1996). Prior to ROSAT, X-ray observations with the Einstein Observatory had suggested that stars in the spectral range B5-A7 are devoid of X-ray emission. Since there is no X-ray emitting mechanism available for these stars (also not for HgMn stars), the usual argument in the case of an X-ray detected star of this spectral type is the existence of an unseen low-mass companion which is responsible for the X-ray emission. The purpose of the present work is to use all available data for our sample of X-ray detected HgMn stars and conclude on the nature of possible companions.

  2. Magnetic fields, spots and weather in chemically peculiar stars

    E-Print Network [OSTI]

    O. Kochukhov

    2007-11-30T23:59:59.000Z

    New observational techniques and sophisticated modelling methods has led to dramatic breakthroughs in our understanding of the interplay between the surface magnetism, atomic diffusion and atmospheric dynamics in chemically peculiar stars. Magnetic Doppler images, constructed using spectropolarimetric observations of Ap stars in all four Stokes parameters, reveal the presence of small-scale field topologies. Abundance Doppler mapping has been perfected to the level where distributions of many different chemical elements can be deduced self-consistently for one star. The inferred chemical spot structures are diverse and do not always trace underlying magnetic field geometry. Moreover, horizontal chemical inhomogeneities are discovered in non-magnetic CP stars and evolving chemical spots are observed for the first time in the bright mercury-manganese star alpha And. These results show that in addition to magnetic fields, another important non-magnetic structure formation mechanism acts in CP stars.

  3. Formation of relativistic jets by collapsing stars to black holes

    E-Print Network [OSTI]

    V. Kryvdyk

    2007-03-12T23:59:59.000Z

    Formation of relativistic jets in the magnetosphere of collapsing stars is considered. These jets will be formed in the polar caps of magnetosphere of collapsing star, where the stellar magnetic field increases during the collapse and the charged particles are accelerated. The jets will generate non-thermal radiation. The analysis of dynamics and emission of particles in the stellar magnetosphere under collapse shows that collapsing stars can by powerful sources of relativistic jets.

  4. Negative feedback effects on star formation history and cosmic reionization

    E-Print Network [OSTI]

    Lei Wang; Jirong Mao; Shouping Xiang; Ye-Fei Yuan

    2008-12-22T23:59:59.000Z

    After considering the effects of negative feedback on the process of star formation, we explore the relationship between star formation process and the associated feedback, by investigating how the mechanical feedback from supernovae(SNe) and radiative feedback from luminous objects regulate the star formation rate and therefore affect the cosmic reionization.Based on our present knowledge of the negative feedback theory and some numerical simulations, we construct an analytic model in the framework of the Lambda cold dark matter model. In certain parameter regions, our model can explain some observational results properly. In large halos(T_vir>10000 K), both mechanical and radiative feedback have a similar behavior: the relative strength of negative feedback reduces as the redshift decreases. In contrast, in small halos (T_virfeedback gets stronger when the redshift decreases. And the star formation rate in these small halos depends very weakly on the star-formation efficiency. Our results show that the radiative feedback is important for the early generation stars. It can suppress the star formation rate considerably. But the mechanical feedback from the SNe explosions is not able to affect the early star formation significantly. The early star formation in small-halo objects is likely to be self-regulated. The radiative and mechanical feedback dominates the star formation rate of the PopII/I stars all along. The feedback from first generation stars is very strong and should not be neglected. However, their effects on the cosmic reionization are not significant, which results in a small contribution to the optical depth of Thomson scattering.

  5. Radio Observations of Masers in Post-AGB Stars

    E-Print Network [OSTI]

    R. M. Deacon; A. J. Green; J. M. Chapman

    2003-10-02T23:59:59.000Z

    We present observations of 86 post-Asymptotic Giant Branch (post-AGB) stars of OH maser transitions, taken with the Parkes Telescope between September 2002 and August 2003. Post-AGB stars are the precursors of planetary nebulae, which have a wide range of morphologies that are not well explained. By studying the circumstellar envelopes of post-AGB stars through the masers produced in them, we hope to shed light on the origin of planetary nebula morphologies.

  6. A search for rapid pulsations among 9 luminous Ap stars

    E-Print Network [OSTI]

    L. M. Freyhammer; D. W. Kurtz; M. S. Cunha; G. Mathys; V. G. Elkin; J. D. Riley

    2008-01-03T23:59:59.000Z

    The rapidly oscillating Ap stars are of importance for studying the atmospheric structure of stars where the process of chemical element diffusion is significant. We have performed a survey for rapid oscillations in a sample of 9 luminous Ap stars, selected from their location in the colour-magnitude diagram as more evolved main-sequence Ap stars that are inside the instability strip for rapidly oscillating Ap (roAp) stars. Until recently this region was devoid of stars with observed rapid pulsations. We used the VLT UV-Visual Echelle Spectrograph (UVES) to obtain high time resolution spectroscopy to make the first systematic spectroscopic search for rapid oscillations in this region of the roAp instability strip. We report 9 null-detections with upper limits for radial-velocity amplitudes of 20 - 65 m/s and precisions of 7 - 20 m/s for combinations of Nd and Pr lines. Cross-correlations confirm these null-results. At least six stars are magnetic and we provide magnetic field measurements for four of them, of which three are newly discovered magnetic stars. It is found that four stars have magnetic fields smaller than ~ 2 kG, which according to theoretical predictions might be insufficient for suppressing envelope convection around the magnetic poles for more evolved Ap stars. Suppression of convection is expected to be essential for the opacity mechanism acting in the hydrogen ionisation zone to drive the high-overtone roAp pulsations efficiently. Our null-results suggest that the more evolved roAp stars may require particularly strong magnetic fields to pulsate. Three of the studied stars do, however, have magnetic fields stronger than 5 kG.

  7. Towards a consistent model for Neutron-Star Sources

    E-Print Network [OSTI]

    W. Kundt

    2002-08-30T23:59:59.000Z

    We are still far from understanding how pulsars pulse, how neutron stars are born, what neutron stars can emit, and in which way they do this. In this short communication, I list 18 alternatives -- several of them old, a few of them new -- which are handled differently by different authors but all of which are crucial for a model of neutron stars to be viable.

  8. OXYGEN ISOTOPIC RATIOS IN COOL R CORONAE BOREALIS STARS

    SciTech Connect (OSTI)

    Garcia-Hernandez, D. A. [Instituto de Astrofisica de Canarias (IAC), C/Via Lactea s/n, 38200 La Laguna, Tenerife (Spain); Lambert, David L. [W. J. McDonald Observatory, University of Texas at Austin. 1 University Station, C1400. Austin, TX 78712-0259 (United States); Rao, N. Kameswara [Indian Institute of Astrophysics, Bangalore 560 034 (India); Hinkle, Ken H. [National Optical Astronomy Observatory (NOAO), Tucson, AZ 85726 (United States); Eriksson, Kjell, E-mail: agarcia@iac.e, E-mail: dll@astro.as.utexas.ed, E-mail: nkrao@iiap.res.i, E-mail: hinkle@noao.ed, E-mail: Kjell.Eriksson@astro.uu.s [Department of Physics and Astronomy, Uppsala University, Box 515, 75120 Uppsala (Sweden)

    2010-05-01T23:59:59.000Z

    We investigate the relationship between R Coronae Borealis (RCB) stars and hydrogen-deficient carbon (HdC) stars by measuring precise {sup 16}O/{sup 18}O ratios for five cool RCB stars. The {sup 16}O/{sup 18}O ratios are derived by spectrum synthesis from high-resolution (R {approx} 50, 000) K-band spectra. Lower limits to the {sup 16}O/{sup 17}O and {sup 14}N/{sup 15}N ratios as well as Na and S abundances (when possible) are also given. RCB stars in our sample generally display less {sup 18}O than HdC stars-the derived {sup 16}O/{sup 18}O ratios range from 3 to 20. The only exception is the RCB star WX CrA, which seems to be an HdC-like star with {sup 16}O/{sup 18}O = 0.3. Our result of a higher {sup 16}O/{sup 18}O ratio for the RCB stars must be accounted for by a theory of the formation and evolution of HdC and RCB stars. We speculate that a late dredge-up of products of He burning, principally {sup 12}C and {sup 16}O, may convert an {sup 18}O-rich HdC star into an {sup 18}O-poor RCB star as the H-deficient star begins its final evolution from a cool supergiant to the top of the white dwarf cooling track.

  9. Continuous-time quantum walks on star graphs

    SciTech Connect (OSTI)

    Salimi, S. [Department of Physics, University of Kurdistan, P.O. Box 66177-15175, Sanandaj (Iran, Islamic Republic of)], E-mail: shsalimi@uok.ac.ir

    2009-06-15T23:59:59.000Z

    In this paper, we investigate continuous-time quantum walk on star graphs. It is shown that quantum central limit theorem for a continuous-time quantum walk on star graphs for N-fold star power graph, which are invariant under the quantum component of adjacency matrix, converges to continuous-time quantum walk on K{sub 2} graphs (complete graph with two vertices) and the probability of observing walk tends to the uniform distribution.

  10. On the ultimate fate of AM Her stars

    E-Print Network [OSTI]

    F. Meyer; E. Meyer-Hofmeister

    1999-05-06T23:59:59.000Z

    We suggest, that the magnetic field of the white dwarf in AM Her systems loses coupling to the secondary star when the latter becomes non-magnetic at the transition from a late main sequence star to a cool degenerate brown dwarf. This leads to spin-up of the primary white dwarf. After synchronous rotation is lost the systems do not appear as AM Her stars anymore. We discuss the further evolution of such systems.

  11. Model atmospheres and SEDs of chemically peculiar stars

    E-Print Network [OSTI]

    Yakiv V. Pavlenko

    2002-09-02T23:59:59.000Z

    Procedure and results of computations of stellar model atmospheres and spectral energy distributions are discussed. Model atmospheres of some chemically peculiar stars are computed taking into account detailed information about their abundances: -- R CrB-like stars of Teff $\\sim$ 7000 K, -- Sakurai's object (V4334 Sgr) of 4000 $<$ \\Tef $<$ 7000 K -- Przybylski's star of Teff $\\sim$ 6500 K. We show that our self-consistent approach provides a unique possibility to investigate the temporal changes of physical parameters of chemically peculiar stars. Some problems of computation of model atmospheres of M and C-giants are also considered.

  12. ae stars driving: Topics by E-print Network

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

    - Isolated Herbig Ae Stars Driving Herbig-Haro Flows Astrophysics (arXiv) Summary: Infrared photometry and spectroscopy covering a time span of a quarter century are presented...

  13. Astrometry of the OH masers of 4 Mira stars

    E-Print Network [OSTI]

    Wouter Vlemmings; Huib Jan van Langevelde; Phil Diamond

    2003-09-16T23:59:59.000Z

    The OH main line masers in circumstellar shells were observed with astrometric VLBI in order to accurately determine the position of the star, as well as its motion, including the parallax. Results are presented on 4 Mira stars monitored for 2 - 8 years with the VLBA. The data show that in some stars the VLBI detection is dominated by blue-shifted emission that is associated with the stellar image amplified by the maser shell in front of the star. In other cases the maser is not directly tied to the stellar position, but still persistent enough to measure proper motion and parallax.

  14. Feedback Processes [in Massive Star Formation]: A Theoretical Perspective

    E-Print Network [OSTI]

    Mordecai-Mark Mac Low

    2007-11-26T23:59:59.000Z

    I review the evidence for the importance of feedback from massive stars at small and large scales. The feedback mechanisms include accretion luminosity, ionizing radiation, collimated outflows, and stellar winds. The good news is that feedback doesn't entirely prevent the formation of massive stars, while the bad news is that we don't know what does limit their masses. Feedback from massive stars also influences their surroundings. I argue that this does not produce a triggering efficiency above unity, nor does it prevent lots of prompt star formation in GMCs, though it may preserve massive remnants of the clouds for many dynamical times.

  15. Department of Energy Honors 50 ENERGY STAR® Partners that Saved...

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

    security." ENERGY STAR began in 1992 as a voluntary, market-based partnership to reduce air pollution through increased energy efficiency. Today, DOE, in partnership with EPA,...

  16. STAR Images: Image gallery from the Solenoidal Tracker at RHIC

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The primary physics task of STAR is to study the formation and characteristics of the quark-gluon plasma (QGP), a state of matter believed to exist at sufficiently high energy densities. STAR consists of several types of detectors, each specializing in detecting certain types of particles or characterizing their motion. These detectors allow final statements to be made about the collision. The gallery of STAR images makes available a small collection of event-generated images from Gold-Beam experiments, a simulation of TCP Drift, and a library of STAR instrument and construction photos.

  17. A Random Walk through Star and Planet Formation

    E-Print Network [OSTI]

    Maness, Holly

    2010-01-01T23:59:59.000Z

    and its Neptune-Mass Planet 3.1 Introduction . . . . . . .of Low Mass Star Formation . . . . . 1.3 Planet FormationConstraining Theories of Planet Formation and Evolution .

  18. The Massive Star Population of Cygnus OB2

    E-Print Network [OSTI]

    Wright, Nicholas J; Mohr-Smith, Michael

    2015-01-01T23:59:59.000Z

    We have compiled a significantly updated and comprehensive census of massive stars in the nearby Cygnus OB2 association by gathering and homogenising data from across the literature. The census contains 169 primary OB stars, including 52 O-type stars and 3 Wolf-Rayet stars. Spectral types and photometry are used to place the stars in a Hertzprung-Russell diagram, which is compared to both non-rotating and rotating stellar evolution models, from which stellar masses and ages are calculated. The star formation history and mass function of the association are assessed, and both are found to be heavily influenced by the evolution of the most massive stars to their end states. We find that the mass function of the most massive stars is consistent with a `universal' power-law slope of Gamma = 1.3. The age distribution inferred from stellar evolutionary models with rotation and the mass function suggest the majority of star formation occurred more or less continuously between 1 and 7 Myr ago, in agreement with studi...

  19. PROPERTIES OF OSCILLATION MODES IN SUBGIANT STARS OBSERVED BY KEPLER

    SciTech Connect (OSTI)

    Benomar, O.; Bedding, T. R.; Stello, D.; White, T. R.; Kuehn, C. A. [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Mosser, B.; Belkacem, K. [LESIA, Observatoire de Paris, CNRS UMR 8109, Universite Paris Diderot, 5 Place J. Janssen, F-92195 Meudon (France); Garcia, R. A. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot (France); IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Deheuvels, S. [Institut de Recherche en Astrophysique et Planetologie, Universite de Toulouse, UPS-OMP, CNRS, 14 Avenue Edouard Belin, F-31400 Toulouse (France); Christensen-Dalsgaard, J. [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)

    2013-04-20T23:59:59.000Z

    Mixed modes seen in evolved stars carry information on their deeper layers that can place stringent constraints on their physics and on their global properties (mass, age, etc.). In this study, we present a method to identify and measure all oscillatory mode characteristics (frequency, height, width). Analyzing four subgiant stars, we present the first measure of the effect of the degree of mixture on the l = 1 mixed mode characteristics. We also show that some stars have measurable l = 2 mixed modes and discuss the interest of their measure to constrain the deeper layers of stars.

  20. Columbia Water & Light- Home Performance with ENERGY STAR Loan

    Broader source: Energy.gov [DOE]

    The Columbia Water & Light (CWL) Home Performance with ENERGY STAR program allows Columbia residents to finance energy efficiency improvements to homes with affordable, low-interest loans with...

  1. Calendar Year 2007 Program Benefits for ENERGY STAR Labeled Products

    E-Print Network [OSTI]

    Sanchez, Marla Christine

    2008-01-01T23:59:59.000Z

    increasing market penetration of ENERGY STAR HVAC and anyHVAC is expressed in million square feet 7) Roofing is expressed in billion square feet 8) PC market

  2. Calendar Year 2008 Program Benefits for ENERGY STAR Labeled Products

    E-Print Network [OSTI]

    Homan, GregoryK

    2010-01-01T23:59:59.000Z

    increasing market penetration of ENERGY STAR HVAC and anyHVAC is expressed in million square feet 7) Roofing is expressed in billion square feet 8) PC market

  3. Delmarva Power- Home Performance with Energy Star Incentive Program

    Broader source: Energy.gov [DOE]

    Delmarva Power and Light Company offers the Home Performance with Energy Star Program, which provides incentives for residential customers who have audits performed by participating contractors....

  4. astrophysics connecting stars: Topics by E-print Network

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

    the structure and evolution of single and multiple stars, compact objects, SNe, gamma-ray bursts, solar neutrinos, and extreme physics on stellar scales. Central to the progress...

  5. Scattering from Star Polymers including Excluded Volume Effects

    SciTech Connect (OSTI)

    Li, Xin [ORNL; Do, Changwoo [ORNL; Liu, Yun [National Institute of Standards and Technology (NIST); Sanchez-Diaz, Luis E [ORNL; Hong, Kunlun [ORNL; Smith, Greg [ORNL; Chen, Wei-Ren [ORNL

    2014-01-01T23:59:59.000Z

    In this work we present a new model for the form factor of a star polymer consisting of self-avoiding branches. This new model incorporates excluded volume effects and is derived from the two point correlation function for a star polymer.. We compare this model to small angle neutron scattering (SANS) measurements from polystyrene (PS) stars immersed in a good solvent, tetrahydrofuran (THF). It is shown that this model provides a good description of the scattering signature originating from the excluded volume effect and it explicitly elucidates the connection between the global conformation of a star polymer and the local stiffness of its constituent branch.

  6. Magic Valley Electric Cooperative- ENERGY STAR Builders Program (Texas)

    Broader source: Energy.gov [DOE]

    Magic Valley Electric Cooperative's (MVEC) ENERGY STAR Builders Program offers a variety of incentives to builders of energy efficiency homes within MVEC service territory. Incentives are provided...

  7. Carbon and Strontium Abundances of Metal-Poor Stars

    E-Print Network [OSTI]

    David K. Lai; Jennifer A. Johnson; Michael Bolte; Sara Lucatello

    2007-06-20T23:59:59.000Z

    We present carbon and strontium abundances for 100 metal-poor stars measured from R$\\sim $7000 spectra obtained with the Echellette Spectrograph and Imager at the Keck Observatory. Using spectral synthesis of the G-band region, we have derived carbon abundances for stars ranging from [Fe/H]$=-1.3$ to [Fe/H]$=-3.8$. The formal errors are $\\sim 0.2$ dex in [C/Fe]. The strontium abundance in these stars was measured using spectral synthesis of the resonance line at 4215 {\\AA}. Using these two abundance measurments along with the barium abundances from our previous study of these stars, we show it is possible to identify neutron-capture-rich stars with our spectra. We find, as in other studies, a large scatter in [C/Fe] below [Fe/H]$ = -2$. Of the stars with [Fe/H]$carbon-rich metal-poor stars. The Sr and Ba abundances show that three of the carbon-rich stars are neutron-capture-rich, while two have normal Ba and Sr. This fraction of carbon enhanced stars is consistent with other studies that include this metallicity range.

  8. accreting compact stars: Topics by E-print Network

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

    of the millisecond brightness oscillations from low mass X-ray binaries during thermonuclear bursts can provide us with important information about compact star parameters....

  9. Home Performance with ENERGY STAR - Webinar Slides | Department...

    Energy Savers [EERE]

    with ENERGY STAR - 2014 BTO Peer Review Better Buildings Neighborhood Program Home Accomplishments History Better Buildings Partners Stories Interviews Videos Contact Us...

  10. PEPCO- Home Performance with Energy Star Incentive Program

    Broader source: Energy.gov [DOE]

    The Potomac Electric Power Company (PEPCO) offers the Home Performance with Energy Star Program which provides incentives for residential customers who have audits performed by participating...

  11. The Federal Guiding Principles Checklist in ENERGY STAR Portfolio

    Office of Energy Efficiency and Renewable Energy (EERE)

    This webcast will teach Federal energy and sustainability professionals how to use the ENERGY STAR measurement and tracking tool, Portfolio Manager, to help ensure compliance with the Guiding...

  12. A Heavy Flavor Tracker for STAR

    SciTech Connect (OSTI)

    Chasman, C.; Beavis, D.; Debbe, R.; Lee, J.H.; Levine, M.J.; Videbaek, F.; Xu, Z.; Kleinfelder, S.; Li, S.; Cendejas, R.; Huang, H.; Sakai, S.; Whitten, C.; Joseph, J.; Keane, D.; Margetis, S.; Rykov, V.; Zhang, W.M.; Bystersky, M.; Kapitan, J.; Kushpil, V.; Sumbera, M.; Baudot, J.; Hu-Guo, C.; Shabetai, A.; Szelezniak, M.; Winter, M.; Kelsey, J.; Milner, R.; Plesko, M.; Redwine, R.; Simon, F.; Surrow, B.; Van Nieuwenhuizen, G.; Anderssen, E.; Dong, X.; Greiner, L.; Matis, H.S.; Morgan, S.; Ritter, H.G.; Rose, A.; Sichtermann, E.; Singh, R.P.; Stezelberger, T.; Sun, X.; Thomas, J.H.; Tram, V.; Vu, C.; Wieman, H.H.; Xu, N.; Hirsch, A.; Srivastava, B.; Wang, F.; Xie, W.; Bichsel, H.

    2008-02-25T23:59:59.000Z

    The STAR Collaboration proposes to construct a state-of-the-art microvertex detector,the Heavy Flavor Tracker (HFT), utilizing active pixel sensors and silicon strip technology. The HFT will significantly extend the physics reach of the STAR experiment for precision measurement of the yields and spectra of particles containing heavy quarks. This will be accomplished through topological identification of D mesons by reconstruction of their displaced decay vertices with a precision of approximately 50 mu m in p+p, d+A, and A+A collisions. The HFT consists of 4 layers of silicon detectors grouped into two sub-systems with different technologies, guaranteeing increasing resolution when tracking from the TPC and the Silicon Strip Detector (SSD) towards the vertex of the collision. The Intermediate Silicon Tracker (IST), consisting of two layers of single-sided strips, is located inside the SSD. Two layers of Silicon Pixel Detector (PIXEL) are inside the IST. The PIXEL detectors have the resolution necessary for a precision measurement of the displaced vertex. The PIXEL detector will use CMOS Active Pixel Sensors (APS), an innovative technology never used before in a collider experiment. The APSsensors are only 50 mu m thick and at a distance of only 2.5 cm from the interaction point. This opens up a new realm of possibilities for physics measurements. In particular, a thin detector (0.28percent radiation length per layer) in STAR makes it possible to do the direct topological reconstruction of open charm hadrons down to very low pT by the identification of the charged daughters of the hadronic decay.

  13. IntrAst2 (Petrovay) The distribution of stars THE SPATIAL DISTRIBUTION OF STARS

    E-Print Network [OSTI]

    Petrovay, Kristóf

    generic method: spectral type + lumin. class place on HRD absolute magnitude: Applying it individually) The distribution of stars SURFACE BRIGHTNESS Astronomical unit: 1µ = 1m / " Night sky: 22µ Night sky in city: 18µ Daytime sky: -8µ Solar disk: -13µ Physical unit: I intensity energy/time/area/solid angle [W/m2 /sr

  14. Energy Star Appliances 1 Texas A&M AgriLife Extension Service ENERGY STAR Appliances

    E-Print Network [OSTI]

    Energy Star® Appliances 1 Texas A&M AgriLife Extension Service ENERGY STAR® Appliances ENERGY STAR®-labeled appliances save you money by using less electricity and water than other appliances. Better appliance energy efficiency comes from quality materials and technologically advanced materials. Although energy efficient

  15. 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.

  16. Photon emission from bare quark stars

    E-Print Network [OSTI]

    B. G. Zakharov

    2010-08-16T23:59:59.000Z

    We investigate the photon emission from the electrosphere of a quark star. It is shown that at temperatures T\\sim 0.1-1 MeV the dominating mechanism is the bremsstrahlung due to bending of electron trajectories in the mean Coulomb field of the electrosphere. The radiated energy for this mechanism is much larger than that for the Bethe-Heitler bremsstrahlung. The energy flux from the mean field bremsstrahlung exceeds the one from the tunnel e^{+}e^{-} pair creation as well. We demonstrate that the LPM suppression of the photon emission is negligible.

  17. Colored condensates deep inside neutron stars

    E-Print Network [OSTI]

    David Blaschke

    2014-07-28T23:59:59.000Z

    It is demonstrated how in the absence of solutions for QCD under conditions deep inside compact stars an equation of state can be obtained within a model that is built on the basic symmetries of the QCD Lagrangian, in particular chiral symmetry and color symmetry. While in the vacuum the chiral symmetry is spontaneously broken, it gets restored at high densities. Color symmetry, however, gets broken simultaneously by the formation of colorful diquark condensates. It is shown that a strong diquark condensate in cold dense quark matter is essential for supporting the possibility that such states could exist in the recently observed pulsars with masses of 2 $M_\\odot$.

  18. Mixing zones in magnetized differentially rotating stars

    E-Print Network [OSTI]

    V. Urpin

    2005-09-29T23:59:59.000Z

    We study the secular instability of magnetized differentially rotating radiative zones taking account of viscosity and magnetic and thermal diffusivities. The considered instability generalizes the well-known Goldreich-Schubert-Fricke instability for the case of a sufficiently strong magnetic field. In magnetized stars, instability can lead to a formation of non-spherical unstable zones where weak turbulence mixes the material between the surface and interiors. Such unstable zones can manifest themselves by a non-spherical distribution of abundance anormalies on the stellar surface.

  19. Radiative Levitation in Hot Horizontal Branch Stars

    E-Print Network [OSTI]

    W. Landsman

    1999-06-08T23:59:59.000Z

    There is now considerable evidence that horizontal branch (HB) stars hotter than about 11,500 K experience an enormous enhancement of their photospheric iron abundance due to radiative levitation. In globular clusters, the photospheric iron abundance can reach values of [Fe/H] ~ +0.3, or up to two orders of magnitude higher than the cluster iron abundance. Model atmospheres which take into account the iron overabundance are needed for understanding the appearance of the HB in globular cluster color-magnitude diagrams (CMDs), for the derivation of accurate luminosities, gravities and masses, and for the ultraviolet spectral synthesis of old, metal-poor stellar populations.

  20. ULTRACAM photometry of eclipsing cataclysmic variable stars

    E-Print Network [OSTI]

    William James Feline

    2008-06-04T23:59:59.000Z

    The accurate determination of the masses of cataclysmic variable stars is critical to our understanding of their origin, evolution and behaviour. Observations of cataclysmic variables also afford an excellent opportunity to constrain theoretical physical models of the accretion discs housed in these systems. In particular, the brightness distributions of the accretion discs of eclipsing systems can be mapped at a spatial resolution unachievable in any other astrophysical situation. This thesis addresses both of these important topics via the analysis of the light curves of six eclipsing dwarf novae, obtained using ULTRACAM, a novel high-speed imaging photometer.

  1. Gravitomagnetism in superconductors and compact stars

    E-Print Network [OSTI]

    Cosimo Bambi

    2007-10-10T23:59:59.000Z

    There are three experimentally observed effects in rotating superconductors that are so far unexplained. Some authors have tried to interpret such a phenomena as possible new gravitational properties of coherent quantum systems: in particular, they suggest that the gravitomagnetic field of that kind of matter may be many orders of magnitude stronger than the one expected in the standard theory. Here I show that this interpretation would be in conflict with the common belief that neutron stars have neutrons in superfluid state and protons in superconductive one.

  2. The metallicity of circumnuclear star forming regions

    E-Print Network [OSTI]

    A. I. Diaz; E. Terlevich; M. Castellanos; G. F. Hagele

    2006-10-26T23:59:59.000Z

    We present a spectrophotometric study of circumnuclear star forming regions (CNSFR) in the early type spiral galaxies: NGC 2903, NGC 3351 and NGC 3504, all of them of over solar metallicity according to standard empirical calibrations. A detailed determination of their abundances is made after careful subtraction of the very prominent underlying stellar absorption. It is found that most regions show the highest abundances in HII region-like objects. The relative N/O and S/O abundances are discussed. In is also shown that CNSFR, as a class, segregate from the disk HII region family, clustering around smaller ``softness parameter" -- \\eta' -- values, and therefore higher ionizing temperatures.

  3. The metallicity of circumnuclear star forming regions

    E-Print Network [OSTI]

    Díaz, A I; Castellanos, M; Hägele, G F

    2006-01-01T23:59:59.000Z

    We present a spectrophotometric study of circumnuclear star forming regions (CNSFR) in the early type spiral galaxies: NGC 2903, NGC 3351 and NGC 3504, all of them of over solar metallicity according to standard empirical calibrations. A detailed determination of their abundances is made after careful subtraction of the very prominent underlying stellar absorption. It is found that most regions show the highest abundances in HII region-like objects. The relative N/O and S/O abundances are discussed. In is also shown that CNSFR, as a class, segregate from the disk HII region family, clustering around smaller ``softness parameter" -- \\eta' -- values, and therefore higher ionizing temperatures.

  4. 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.

  5. Energy Star Rebate Finder | 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 being directedAnnual SiteofEvaluating A PotentialJump to:Emminol Jump to:EnergEnergyEnergyOpenEIEnergyEnergyStar

  6. CalStar Products | 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 being directedAnnualProperty EditCalifornia:Power LP Biomass Facilityin Charts Jump to:ListCRED:CalStar Products

  7. Solar Star NAFB 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:Ezfeedflag JumpID-f < RAPID‎ |RippeyInformationSodaAtlassource History ViewSolar Star

  8. StarSolar Corporation | 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 YouKizildere IRaghuraji Agro Industries Pvt LtdShawangunk,SoutheastSt. Francis(Redirected fromStarSolar Corporation Jump

  9. MagStar Technologies | 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 YouKizildere I Geothermal Pwer Plant Jump to:LandownersLuther, Oklahoma:EnergyECOFlorida:MadisonYork: EnergyMagStar

  10. DarkStar VI | 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,DOE Facility Database Data and Resources11-DNADalyDanishDarajatDarien,DarkStar VI

  11. 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.

  12. 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.

  13. E-Print Network 3.0 - ae star hd Sample Search Results

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

    field measurements of the Herbig Ae stars HD 101412 (left panel) and HD 150193 (right panel) (FORS 2... cool stars and solar-like stars Instrumentation The most successful...

  14. E-Print Network 3.0 - ae star hd101412 Sample Search Results

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

    field measurements of the Herbig Ae stars HD 101412 (left panel) and HD 150193 (right panel) (FORS 2... cool stars and solar-like stars Instrumentation The most successful...

  15. NASA's RXTE captures thermonuclear behavior of unique neutron star | EurekAlert! Science ..

    E-Print Network [OSTI]

    ... 2012 NASA's RXTE captures thermonuclear behavior of unique neutron star ... powered by a barrage of thermonuclear explosions on the star's ... minutes and caused by a thermonuclear explosion on the neutron star ...

  16. Plasmon excitations in homogeneous neutron star matter

    E-Print Network [OSTI]

    Marcello Baldo; Camille Ducoin

    2009-07-01T23:59:59.000Z

    We study the possible collective plasma modes which can affect neutron-star thermodynamics and different elementary processes in the baryonic density range between nuclear saturation ($\\rho_0$) and $3\\rho_0$. In this region, the expected constituents of neutron-star matter are mainly neutrons, protons, electrons and muons ($npe\\mu$ matter), under the constraint of beta equilibrium. The elementary plasma excitations of the $pe\\mu$ three-fluid medium are studied in the RPA framework. We emphasize the relevance of the Coulomb interaction among the three species, in particular the interplay of the electron and muon screening in suppressing the possible proton plasma mode, which is converted into a sound-like mode. The Coulomb interaction alone is able to produce a variety of excitation branches and the full spectral function shows a rich structure at different energy. The genuine plasmon mode is pushed at high energy and it contains mainly an electron component with a substantial muon component, which increases with density. The plasmon is undamped for not too large momentum and is expected to be hardly affected by the nuclear interaction. All the other branches, which fall below the plasmon, are damped or over-damped.

  17. A Successful Targeted Search for Hypervelocity Stars

    E-Print Network [OSTI]

    Warren R. Brown; Margaret J. Geller; Scott J. Kenyon; Michael J. Kurtz

    2006-01-25T23:59:59.000Z

    Hypervelocity stars (HVSs) travel with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Following our discovery of the first HVS, we have undertaken a dedicated survey for more HVSs in the Galactic halo and present here the resulting discovery of two new HVSs: SDSS J091301.0+305120 and SDSS J091759.5+672238, traveling with Galactic rest-frame velocities at least +558+-12 and +638+-12 km/s, respectively. Assuming the HVSs are B8 main sequence stars, they are at distances ~75 and ~55 kpc, respectively, and have travel times from the Galactic Center consistent with their lifetimes. The existence of two B8 HVSs in our 1900 deg^2 survey, combined with the Yu & Tremaine HVS rate estimates, is consistent with HVSs drawn from a standard initial mass function but inconsistent with HVS drawn from a truncated mass function like the one in the top-heavy Arches cluster. The travel times of the five currently known HVSs provide no evidence for a burst of HVSs from a major in-fall event at the Galactic Center in the last \\~160 Myr.

  18. Mutual Friction in Superfluid Neutron Stars

    E-Print Network [OSTI]

    N. Andersson; T. Sidery; G. L. Comer

    2005-10-03T23:59:59.000Z

    We discuss vortex-mediated mutual friction in the two-fluid model for superfluid neutron star cores. Our discussion is based on the general formalism developed by Carter and collaborators, which makes due distinction between transport velocity and momentum for each fluid. This is essential for an implementation of the so-called entrainment effect, whereby the flow of one fluid imparts momentum in the other and vice versa. The mutual friction follows by balancing the Magnus force that acts on the quantised neutron vortices with a resistive force due to the scattering of electrons off of the magnetic field with which each vortex core is endowed. We derive the form of the macroscopic mutual friction force which is relevant for a model based on smooth-averaging over a collection of vortices. We discuss the coefficients that enter the expression for this force, and the timescale on which the two interpenetrating fluids in a neutron star core are coupled. This discussion confirms that our new formulation accords well with previous work in this area.

  19. Radial velocities of southern visual multiple stars

    SciTech Connect (OSTI)

    Tokovinin, Andrei [Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile); Pribulla, Theodor [Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranská Lomnica (Slovakia); Fischer, Debra, E-mail: atokovinin@ctio.noao.edu, E-mail: pribulla@ta3.sk, E-mail: debra.fischer@gmail.com [Department of Astronomy, Yale University, New Haven, CT 06511 (United States)

    2015-01-01T23:59:59.000Z

    High-resolution spectra of visual multiple stars were taken in 2008–2009 to detect or confirm spectroscopic subsystems and to determine their orbits. Radial velocities of 93 late-type stars belonging to visual multiple systems were measured by numerical cross-correlation. We provide the individual velocities, the width, and the amplitude of the Gaussians that approximate the correlations. The new information on the multiple systems resulting from these data is discussed. We discovered double-lined binaries in HD 41742B, HD 56593C, and HD 122613AB, confirmed several other known subsystems, and constrained the existence of subsystems in some visual binaries where both components turned out to have similar velocities. The orbits of double-lined subsystems with periods of 148 and 13 days are computed for HD 104471 Aa,Ab and HD 210349 Aa,Ab, respectively. We estimate individual magnitudes and masses of the components in these triple systems and update the outer orbit of HD 104471 AB.

  20. Gravitational lensing in eclipsing binary stars

    E-Print Network [OSTI]

    T. R. Marsh

    2000-12-18T23:59:59.000Z

    I consider the effect of the gravitational deflection of light upon the light curves of eclipsing binary stars, focussing mainly upon systems containing at least one white dwarf component. In absolute terms the effects are small, however they are strongest at the time of secondary eclipse when the white dwarf transits its companion, and act to reduce the depth of this feature. If not accounted for, this may lead to under-estimation of the radius of the white dwarf compared to that of its companion. I show that the effect is significant for plausible binary parameters, and that it leads to ~25% reduction in the transit depth in the system KPD 1930+2752. The reduction of eclipse depth is degenerate with the stellar radius ratio, and therefore cannot be used to establish the existence of lensing. A second order effect of the light bending is to steepen the ingress and egress features of the secondary eclipse relative to the primary eclipse, although it will be difficult to see this in practice. I consider also binaries containing neutron stars and black-holes. I conclude that, although relatively large effects are possible in such systems, a combination of rarity, faintness and intrinsic variability make it unlikely that lensing will be detectable in them.

  1. Shear viscosity in neutron star cores

    E-Print Network [OSTI]

    P. S. Shternin; D. G. Yakovlev

    2008-08-21T23:59:59.000Z

    We calculate the shear viscosity $\\eta = \\eta_{e\\mu}+\\eta_{n}$ in a neutron star core composed of nucleons, electrons and muons ($\\eta_{e\\mu}$ being the electron-muon viscosity, mediated by collisions of electrons and muons with charged particles, and $\\eta_{n}$ the neutron viscosity, mediated by neutron-neutron and neutron-proton collisions). Deriving $\\eta_{e\\mu}$, we take into account the Landau damping in collisions of electrons and muons with charged particles via the exchange of transverse plasmons. It lowers $\\eta_{e\\mu}$ and leads to the non-standard temperature behavior $\\eta_{e\\mu}\\propto T^{-5/3}$. The viscosity $\\eta_{n}$ is calculated taking into account that in-medium effects modify nucleon effective masses in dense matter. Both viscosities, $\\eta_{e\\mu}$ and $\\eta_{n}$, can be important, and both are calculated including the effects of proton superfluidity. They are presented in the form valid for any equation of state of nucleon dense matter. We analyze the density and temperature dependence of $\\eta$ for different equations of state in neutron star cores, and compare $\\eta$ with the bulk viscosity in the core and with the shear viscosity in the crust.

  2. 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.

  3. Nuclear Equation of State and Neutron Star Cooling

    E-Print Network [OSTI]

    Yeunhwan Lim; Chang Ho Hyun; Chang-Hwan Lee

    2015-01-19T23:59:59.000Z

    We investigate the effects of the nuclear equation of state (EoS) to the neutron star cooling. New era for nuclear EoS has begun after the discovery of $\\sim 2\\msun$ neutron stars PSR J1614$-$2230 and PSR J0348$+$0432 [1, 2]. Also recent works on the mass and radius of neutron stars from low-mass X-ray binaries [3] strongly constrain the EoS of nuclear matter. On the other hand, observations of the neutron star in Cassiopeia A (Cas A) more than 10 years confirmed the existence of nuclear superfluidity [4, 5]. Nuclear superfluidity reduces the heat capacities as well as neutrino emissivities. With nuclear superfluidity the neutrino emission processes are highly suppressed, and the existence of superfluidity makes the cooling path quite different from that of the standard cooling process. Superfluidity also allows new neutrino emission process, which is called `Pair Breaking and Formation'(PBF). PBF is a fast cooling process and can explain the fast cooling rate of neutron star in Cas A. Therefore, it is essential to add the superfluidity effect in the neutron star cooling process. In this work, we simulate neutron star cooling curves using both non-relativistic and relativistic nuclear models. The existence of too early direct Urca process shows that some of nuclear models do not fit for the cooling simulation. After this first selection process, the nuclear pairing gaps are searched using the observational neutron star's age and temperature data.

  4. Utility Rebates for ENERGY STAR Appliances: Are They Effective?

    E-Print Network [OSTI]

    cost. The World Energy Outlook 2009, published by the International Energy Agency (IEA), highlightsUtility Rebates for ENERGY STAR Appliances: Are They Effective? Souvik Datta Sumeet Gulati CEPE;UTILITY REBATES FOR ENERGY STAR APPLIANCES: ARE THEY EFFECTIVE? SOUVIK DATTA ETH Z¨urich SUMEET GULATI

  5. Disorder resistivity of solid neutron-star matter

    E-Print Network [OSTI]

    P. B. Jones

    2004-11-01T23:59:59.000Z

    Lower limits are found for the disorder resistivity of solid neutron-star matter in the neutron-drip region which is amorphous and heterogeneous in nuclear charge. This temperature-independent resistivity, large compared with that produced by phonon scattering, has direct consequences for theories of neutron-star magnetic field generation and evolution.

  6. Lithium in very metal poor thick disk stars

    E-Print Network [OSTI]

    P. Molaro; P. Bonifacio; L. Pasquini

    1997-09-25T23:59:59.000Z

    A search for lithium is performed on seven metal poor dwarfs with metallicities ranging from [Fe/H]=-1.5 down to [Fe/H]=-3.0 but showing disk-like kinematics. These stars belong to the metal poor tail of the Galactic thick disk and they may be also the result of an accretion event (Beers and Sommer-Larsen 1995). The Li 6707.8 A line is present in all the seven dwarfs. The weighted average of the Li abundance for the stars is A(Li)=2.20 (+/-0.06) and is consistent within the errors with the plateau Li abundance of A(Li)=2.24(+/- 0.012) found in genuine halo stars in the same range of metallicities (Bonifacio and Molaro 1997). One of the stars, CS 22182-24, shows somewhat lower Li abundance (A(Li)=1.6(+/-0.40)) and is a candidate to being a Li-poor star. Whether this group of stars belongs to the oldest stars in the disk or to the old population of an external galaxy accreted by the Milky Way, the present observations provide support to the universality of a pre-Galactic Li abundance as is observed in the Galactic halo stars.

  7. Savings Estimates for the ENERGY STAR Voluntary Labeling Program

    E-Print Network [OSTI]

    . This paper presents past and predicted savings for the ENERGY STAR ® labeling program, operated jointly appliances. This report presents savings estimates for a subset of ENERGY STAR program activities, focused primarily on labeled products. We present estimates of the energy, dollar and carbon savings achieved

  8. Boson stars and oscillatons in an inflationary universe

    E-Print Network [OSTI]

    Gyula Fodor; Péter Forgács; Márk Mezei

    2010-07-02T23:59:59.000Z

    Spherically symmetric gravitationally bound, oscillating scalar lumps (boson stars and oscillatons) are considered in Einstein's gravity coupled to massive scalar fields in 1+D dimensional de Sitter-type inflationary space-times. We show that due to inflation bosons stars and oscillatons lose mass through scalar radiation, but at a rate that is exponentially small when the expansion rate is slow.

  9. NEUTRON STAR ENVELOPES AND THERMAL RADIATION FROM THE MAGNETIC SURFACE

    E-Print Network [OSTI]

    NEUTRON STAR ENVELOPES AND THERMAL RADIATION FROM THE MAGNETIC SURFACE in: C. Kouveliotou, J. van.Petersburg, Russia Abstract. The thermal structure of neutron star envelopes is discussed with emphasis on analytic on the opacities and the thermal structure is further reviewed in view of the application to pulsar cooling

  10. Spectral classification of stars based on LAMOST spectra

    E-Print Network [OSTI]

    Liu, Chao; Zhang, Bo; Wan, Jun-Chen; Deng, Li-Cai; Hou, Yonghui; Wang, Yuefei; Yang, Ming; Zhang, Yong

    2015-01-01T23:59:59.000Z

    In this work, we select the high signal-to-noise ratio spectra of stars from the LAMOST data andmap theirMK classes to the spectral features. The equivalentwidths of the prominent spectral lines, playing the similar role as the multi-color photometry, form a clean stellar locus well ordered by MK classes. The advantage of the stellar locus in line indices is that it gives a natural and continuous classification of stars consistent with either the broadly used MK classes or the stellar astrophysical parameters. We also employ a SVM-based classification algorithm to assignMK classes to the LAMOST stellar spectra. We find that the completenesses of the classification are up to 90% for A and G type stars, while it is down to about 50% for OB and K type stars. About 40% of the OB and K type stars are mis-classified as A and G type stars, respectively. This is likely owe to the difference of the spectral features between the late B type and early A type stars or between the late G and early K type stars are very we...

  11. Policy Flash 2015-06 Energy Star and Electronic Products Environmental...

    Energy Savers [EERE]

    Policy Flash 2015-06 Energy Star and Electronic Products Environmental Assessment Tool (EPEAT) Policy Flash 2015-06 Energy Star and Electronic Products Environmental Assessment...

  12. SciTech Connect: The Nuclear Spectroscopic Telescope Array (NuSTAR...

    Office of Scientific and Technical Information (OSTI)

    The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission Citation Details In-Document Search Title: The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission Authors: Harrison,...

  13. Nuclear Star Clusters in Edge-on Galaxies

    E-Print Network [OSTI]

    Anil C. Seth; Julianne J. Dalcanton; Paul W. Hodge; Victor P. Debattista

    2006-06-02T23:59:59.000Z

    From observations of edge-on, late-type galaxies, we present morphological evidence that some nuclear star clusters have experienced in situ star formation. We find three nuclear clusters that, viewed from the edge-on perspective, have both a compact disk-like component and a spheroidal component. In each cluster, the disk components are closely aligned with the major axis of the host galaxy and have bluer colors than the spheroidal components. We spectroscopically verify that one of the observed multiple component clusters has multiple generations of stars. These observations lead us to suggest a formation mechanism for nuclear star clusters, in which stars episodically form in compact nuclear disks, and then lose angular momentum, eventually forming an older spheroid.

  14. Beta Cephei stars in the inner part of the Galaxy

    E-Print Network [OSTI]

    A. Narwid; Z. Kolaczkowski; A. Pigulski; T. Ramza

    2005-10-04T23:59:59.000Z

    From the Fourier analysis of the catalogue of ~200,000 variable candidates in the OGLE-II Galactic fields, we found a sample of about 230 short-period low-amplitude variable stars. From their position in the colour-magnitude diagram and the observed periods (multiple in most cases), we identify the stars as a mixture of Beta Cephei and Delta Scuti stars. Beta Cephei stars from this sample are located in the Galactic disk at distances from 3 to 6 kpc. Many of them shows large range of the excited periods, an indication of high metallicity. We estimate that even a half of the sample of 230 short-period variables we found, can be Beta Cephei stars. The periods alone, however, are rarely sufficient to distinguish between both types of pulsators. We point out, how this can be done observationally.

  15. Bright Stars in the Galactic Globular M5

    E-Print Network [OSTI]

    E. Brocato; V. Castellani; V. Ripepi

    1994-07-07T23:59:59.000Z

    We present a CCD investigation of the galactic globular M5 aimed to increase the statistical relevance of the available sample of evolving bright stars. Previous investigations, limited to the outer cluster region, have been extended toward the cluster center, more than doubling the number of observed luminous stars. On this basis, we discuss a statistically relevant sample, rich of 415 HB stars. The occurrence of a gap in the blue side of the HB is suggested. Comparison to the current evolutionary scenario discloses a good agreement concerning both the C-M diagram location and the relative abundance of stars in the advanced evolutionary phases, supporting our present knowledge of the evolution of low mass stars. Determination of the amount of the original helium content through the ratio R N(HB)/N(RGB) gives $Y = 0.22 \\pm 0.02$.

  16. The Age and Interior Rotation of Stars from Asteroseismology

    E-Print Network [OSTI]

    Aerts, Conny

    2015-01-01T23:59:59.000Z

    We provide a status report on the determination of stellar ages from asteroseismology for stars of various masses and evolutionary stages. The ability to deduce the ages of stars with a relative precision of typically 10 to 20% is a unique opportunity for stellar evolution and also of great value for both galactic and exoplanet studies. Further, a major uncalibrated ingredient that makes stellar evolution models uncertain, is the stellar interior rotation frequency $\\Omega(r)$ and its evolution during stellar life. We summarize the recent achievements in the derivation of $\\Omega(r)$ for different types stars, offering stringent observational constraints on theoretical models. Core-to-envelope rotation rates during the red giant stage are far lower than theoretical predictions, pointing towards the need to include new physical ingredients that allow strong and efficient coupling between the core and the envelope in the models of low-mass stars in the evolutionary phase prior to the core helium burning. Stars ...

  17. Three editions of the Star Catalogue of Tycho Brahe

    E-Print Network [OSTI]

    Verbunt, Frank

    2010-01-01T23:59:59.000Z

    Tycho Brahe completed his catalogue with the positions and magnitudes of 1004 fixed stars in 1598. This catalogue circulated in manuscript form. Brahe edited a shorter version with 777 stars, printed in 1602, and Kepler edited the full catalogue of 1004 stars, printed in 1627. We provide machine-readable versions of the three versions of the catalogue, describe the differences between them and briefly discuss their accuracy on the basis of comparison with modern data from the Hipparcos Catalogue. We also compare our results with earlier analyses by Dreyer (1916) and Rawlins (1993), finding good overall agreement. The magnitudes given by Brahe correlate well with modern values, his longitudes and latitudes have error distributions with widths of about 2 arcmin, with excess numbers of stars with larger errors (as compared to Gaussian distributions), in particular for the faintest stars. Errors in positions larger than 10 arcmin, which comprise about 15 per cent of the entries, are likely due to computing or cop...

  18. NARROW ATOMIC FEATURES FROM RAPIDLY SPINNING NEUTRON STARS

    SciTech Connect (OSTI)

    Bauboeck, Michi; Psaltis, Dimitrios; Oezel, Feryal, E-mail: mbaubock@email.arizona.edu, E-mail: dpsaltis@email.arizona.edu, E-mail: fozel@email.arizona.edu [Astronomy Department, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)] [Astronomy Department, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2013-04-01T23:59:59.000Z

    Neutron stars spinning at moderate rates ({approx}300-600 Hz) become oblate in shape and acquire a nonzero quadrupole moment. In this paper, we calculate the profiles of atomic features from such neutron stars using a ray-tracing algorithm in the Hartle-Thorne approximation. We show that line profiles acquire cores that are much narrower than the widths expected from pure Doppler effects for a large range of observer inclinations. As a result, the effects of both the oblateness and the quadrupole moments of neutron stars need to be taken into account when aiming to measure neutron-star radii from rotationally broadened lines. Moreover, the presence of these narrow cores substantially increases the likelihood of detecting atomic lines from rapidly spinning neutron stars.

  19. STAR (Solenoidal Tracker at RHIC) Figures and Data

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The STAR Collaboration

    The primary physics task of STAR is to study the formation and characteristics of the quark-gluon plasma (QGP), a state of matter believed to exist at sufficiently high energy densities. STAR consists of several types of detectors, each specializing in detecting certain types of particles or characterizing their motion. These detectors work together in an advanced data acquisition and subsequent physics analysis that allows final statements to be made about the collision. The STAR Publications page provides access to all published papers by the STAR Collaboration, and many of them have separate links to the figures and data found in or supporting the paper. See also the data-rich summaries of the research at http://www.star.bnl.gov/central/physics/results/. [See also DDE00230

  20. Neutron Stars in a Varying Speed of Light Theory

    E-Print Network [OSTI]

    A. W. Whinnett

    2003-05-21T23:59:59.000Z

    We study neutron stars in a varying speed of light (VSL) theory of gravity in which the local speed of light depends upon the value of a scalar field $\\phi$. We find that the masses and radii of the stars are strongly dependent on the strength of the coupling between $\\phi$ and the matter field and that for certain choices of coupling parameters, the maximum neutron star mass can be arbitrarily small. We also discuss the phenomenon of cosmological evolution of VSL stars (analogous to the gravitational evolution in scalar-tensor theories) and we derive a relation showing how the fractional change in the energy of a star is related to the change in the cosmological value of the scalar field.

  1. Local and Global Radiative Feedback from Population III Star Formation

    E-Print Network [OSTI]

    O'Shea, Brian W

    2010-01-01T23:59:59.000Z

    We present an overview of recent work that focuses on understanding the radiative feedback processes that are potentially important during Population III star formation. Specifically, we examine the effect of the Lyman-Werner (photodissociating) background on the early stages of primordial star formation, which serves to delay the onset of star formation in a given halo but never suppresses it entirely. We also examine the effect that both photodissociating and ionizing radiation in I-fronts from nearby stellar systems have on the formation of primordial protostellar clouds. Depending on the strength of the incoming radiation field and the central density of the halos, Pop III star formation can be suppressed, unaffected, or even enhanced. Understanding these and other effects is crucial to modeling Population III star formation and to building the earliest generations of galaxies in the Universe.

  2. 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.

  3. 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.

  4. X-ray Emission from Massive StarsX-ray Emission from Massive Stars David CohenDavid Cohen

    E-Print Network [OSTI]

    Cohen, David

    X-ray Emission from Massive StarsX-ray Emission from Massive Stars David CohenDavid Cohen/s)Velocity (km/s) #12;absorption emission emission occulted emission emission UV telescope side side front back #12;absorption emission emission occulted emission emission UV telescope side side front back #12;The

  5. The HI Mass-Star Formation Rate Relation and Self-Regulated Star Formation in Dwarf Galaxies

    E-Print Network [OSTI]

    Edward N Taylor

    2005-11-18T23:59:59.000Z

    We have developed a simple, static model designed to place a very solid lower limit on the star formation rate (SFR) expected in a dwarf disk galaxy, which leads to the prediction of a previously undocumented relation between HI mass, M_HI, and SFR. Over the mass range 10^8--10^10 M_sun, a wide variety of galaxies are observed to follow such a relation -- SFR ~ M_HI^1.4 -- with the same slope and similar scatter to our prediction. Within the model, this relation is a manifestation of self-regulating star formation (SF), in which the ISM is kept warm and stable by a UV interstellar radiation field (ISRF) that is maintained by constant regeneration of O--B stars. Regardless of the actual mode of star formation, it seems that the majority of dwarfs are presently forming stars in the same way.

  6. 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...

  7. 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.

  8. Relativistic MHD Winds from Rotating Neutron Stars

    E-Print Network [OSTI]

    N. Bucciantini; T. A. Thompson; J. Arons; E. Quataert

    2006-12-22T23:59:59.000Z

    We solve the time-dependent dynamics of axisymmetric, general relativistic MHD winds from rotating neutron stars. The mass loss rate is obtained self consistently as a solution of the MHD equations, subject to a finite thermal pressure at the stellar surface. Conditions are chosen to be representative of the neutrino driven phase in newly born magnetars, which have been considered as a possible engine for GRBs. We compute the angular momentum and energy losses as a function of $\\sigma$ and compare them with the analytic expectation from the classical theory of pulsar winds. We observe the convergence to the force-free limit in the energy loss and we study the evolution of the closed zone for increasing magnetization. Results also show that the dipolar magnetic field and the presence of a closed zone do not modify significantly the acceleration and collimation properties of the wind.

  9. 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.

  10. The Star Formation Density at z=7

    E-Print Network [OSTI]

    F. Mannucci

    2006-11-29T23:59:59.000Z

    Near-infrared VLT data of the GOODS-South area were used to look for galaxies at z=7 down to a limiting magnitude of (J+Ks)AB=25.5. No high-redshift candidates were detected, and this provides clear evidence for a strong evolution of the luminosity function between z=6 and z=7, i.e. over a time interval of only 170 Myr. Our constraints provide evidence of a significant decline in the total star formation rate at z=7, which must be less than 40% of that at z=3 and 40-80% of that at z=6. The resulting upper limit to the ionizing flux at z=7 is only marginally consistent with what is required to completely ionize the Universe.

  11. On rotationally driven meridional flows in stars

    E-Print Network [OSTI]

    P. Garaud

    2002-03-21T23:59:59.000Z

    A quasi-steady state model of the consequences of rotation on the hydrodynamical structure of a stellar radiative zone is derived, by studying in particular the role of centrifugal and baroclinic driving of meridional motions in angular-momentum transport. This nonlinear problem is solved numerically assuming axisymmetry of the system, and within some limits, it is shown that there exist simple analytical solutions. The limit of slow rotation recovers Eddington-Sweet theory, whereas it is shown that in the limit of rapid rotation, the system settles into a geostrophic equilibrium. The behaviour of the system is found to be controlled by one parameter only, linked to the Prantl number, the stratification and the rotation rate of the star.

  12. The Corona Australis Star Forming Region

    E-Print Network [OSTI]

    Ralph Neuhäuser; Jan Forbrich

    2008-08-25T23:59:59.000Z

    At a distance of about 130 pc, the Corona Australis molecular cloud complex is one of the nearest regions with ongoing and/or recent star formation. It is a region with highly variable extinction of up to AV~45 mag, containing, at its core, the Coronet protostar cluster. There are now 55 known optically detected members, starting at late B spectral types. At the opposite end of the mass spectrum, there are two confirmed brown dwarf members and seven more candidate brown dwarfs. The CrA region has been most widely surveyed at infrared wavelengths, in X-rays, and in the millimeter continuum, while follow-up observations from centimeter radio to X-rays have focused on the Coronet cluster.

  13. Mid-Infrared Spectra of Be Stars

    E-Print Network [OSTI]

    S. A. Rinehart; J. R. Houck; J. D. Smith

    1999-10-11T23:59:59.000Z

    We present the first medium-resolution ($R\\sim 600$) mid-infrared (8-13.3\\micron) spectra of 11 Be stars. A large number of lines are observed and identified in these spectra, including, as an example, 39 hydrogen recombination lines in the spectrum of $\\gamma$ Cas. In the majority of our spectra, all of the observed lines are attributable to hydrogen recombination. Two of the sources, $\\beta$ Lyr and MWC 349 also show emission from other species. Both of these objects show evidence of [Ne II] emission, and $\\beta$ Lyr also shows evidence of He I emission. We tabulate the effective line strength and line widths for the observed lines, and briefly discuss the physical implications of the observed line series. We also use a simple model of free-free emission to characterize the disks around these sources.

  14. 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.

  15. Star-Formation Knots in IRAS Galaxies

    E-Print Network [OSTI]

    J. B. Hutchings

    1995-11-08T23:59:59.000Z

    Images of IRAS galaxies with a range of IR properties are examined for bright knots, both within and outside the galaxy. These are found almost exclusively in galaxies with steep IR spectra, but over a wide range of IR luminosity, and usually without strong nuclear activity. In most cases, the knots are likely to be star-formation induced by tidal interactions, and are seen in the early stages of such interactions. Detailed photometry is presented of knots in six representative galaxies. The knots appear to have a wide range of colour and luminosity, but it is argued that many are heavily reddened. Knots formed outside the parent galaxy may be a new generation of what later become globular clusters, but they appear to have a wide range of luminosities.

  16. 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.

  17. 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.

  18. STAR inner tracking upgrade - A performance study

    E-Print Network [OSTI]

    Jan Kapitan; for the STAR Collaboration

    2009-01-19T23:59:59.000Z

    Anisotropic flow measurements have demonstrated development of partonic collectivity in $200\\mathrm{GeV}$ Au+Au collisions at RHIC. To understand the partonic EOS, thermalization must be addressed. Collective motion of heavy-flavor (c,b) quarks can be used to indicate the degree of thermalization of the light-flavor quarks (u,d,s). Measurement of heavy-flavor quark collectivity requires direct reconstruction of heavy-flavor hadrons in the low $\\pt$ region. Measurement of open charm spectra to high $\\pt$ can be used to investigate heavy-quark energy loss and medium properties. The Heavy Flavor Tracker (HFT), a proposed upgrade to the STAR experiment at midrapidity, will measure $v_{2}$ of open-charm hadrons to very low $\\pt$ by reconstructing their displaced decay vertices. The innermost part of the HFT is the PIXEL detector (made of two low mass monolithic active pixel sensor layers), which delivers a high precision position measurement close to the collision vertex. The Intermediate Silicon Tracker (IST), a 1-layer strip detector, is essential to improve hit identification in the PIXEL detector when running at full RHIC-II luminosity. Using a full GEANT simulation, open charm measurement capabilities of STAR with the HFT will be shown. Its performance in a broad $\\pt$ range will be demonstrated on $v_{2}$ ($\\pt > 0.5\\mathrm{GeV}/c$) and $R_\\mathrm{CP}$ ($\\pt < 10\\mathrm{GeV}/c$) measurements of $\\D$ meson. Results of reconstruction of $\\Lc$ baryon in heavy-ion collisions are presented.

  19. 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.

  20. 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...