National Library of Energy BETA

Sample records for antiknock in dex

  1. Application of charge stratification, lean burn combustion systems and anti-knock control devices in small two-stroke cycle gasoline engines

    SciTech Connect (OSTI)

    Kuentscher, V.

    1986-01-01

    For essentially reducing the specific fuel consumption in two-stroke cycle engines and the concentration of hydrocarbons (HC) in the exhaust gas, the normal engine was equipped with a new ram tuned fuel injection system. By the application of charge stratification, lean burn combustion, different ignition systems and a special anti-knock device, considerable fuel consumption and HC emission reductions were obtained.

  2. DEX: Increasing the Capability of Scientific Data Analysis Pipelines...

    Office of Scientific and Technical Information (OSTI)

    DEX: Increasing the Capability of Scientific Data Analysis Pipelines by Using Efficient Bitmap Indices to Accelerate Scientific Visualization Citation Details In-Document Search...

  3. Lead distribution in near-surface soils of two Florida cities: Gainesville and Miami

    E-Print Network [OSTI]

    Ma, Lena

    , arithmetic mean; GM, geometric mean; GSD, geometric standard deviation; OC, organic carbon; SCTL, soil clean, and the widespread past use of alkyl-lead compounds as antiknock addi- tives in gasoline, and Pb-based paint

  4. Mineral dust emission from the Bodele Depression, northern Chad, during BoDEx 2005

    E-Print Network [OSTI]

    Washington, Richard

    distribution of this diatomite dust estimated from sun photometer data, using a modified Aeronet retrieval loadings results in a reduction in surface daytime maximum temperature of around 7°C in the Bode´le´ region-blown terrestrial mineral dust. The distribution, properties of mineral dust and its climate impact are poorly

  5. Report on the paper "The number of inversions and the major in-dex of permutations are asymptotically joint-independently-normal",

    E-Print Network [OSTI]

    Zeilberger, Doron

    no bearing on the overall validity of the main result. The main one is the following: the description of the main result on the bottom half of page 2 is inaccurate (and false if interpreted literally

  6. Dexamethasone increases glucose cycling, but not glucose production, in healthy subjects

    SciTech Connect (OSTI)

    Wajngot, A.; Khan, A.; Giacca, A.; Vranic, M.; Efendic, S. )

    1990-11-01

    We established that measurement of glucose fluxes through glucose-6-phosphatase (G-6-Pase; hepatic total glucose output, HTGO), glucose cycling (GC), and glucose production (HGP), reveals early diabetogenic changes in liver metabolism. To elucidate the mechanism of the diabetogenic effect of glucocorticoids, we treated eight healthy subjects with oral dexamethasone (DEX; 15 mg over 48 h) and measured HTGO with (2-3H)glucose and HGP with (6-3H)glucose postabsorptively and during a 2-h glucose infusion (11.1 mumol.kg-1.min-1). (2-3H)- minus (6-3H)glucose equals GC. DEX significantly increased plasma glucose, insulin, C peptide, and HTGO, while HGP was unchanged. In controls and DEX, glucose infusion suppressed HTGO (82 vs. 78%) and HGP (87 vs. 91%). DEX increased GC postabsorptively (three-fold) P less than 0.005 and during glucose infusion (P less than 0.05) but decreased metabolic clearance and glucose uptake (Rd), which eventually normalized, however. Because DEX increased HTGO (G-6-Pase) and not HGP (glycogenolysis + gluconeogenesis), we assume that DEX increases HTGO and GC in humans by activating G-6-Pase directly, rather than by expanding the glucose 6-phosphate pool. Hyperglycemia caused by peripheral effects of DEX can also contribute to an increase in GC by activating glucokinase. Therefore, measurement of glucose fluxes through G-6-Pase and GC revealed significant early effects of DEX on hepatic glucose metabolism, which are not yet reflected in HGP.

  7. DEX: Increasing the Capability of Scientific Data Analysis Pipelines by

    Office of Scientific and Technical Information (OSTI)

    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 Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing BacteriaConnect Collidertransfer (Journal Article) | SciTechFLARES

  8. DEX: Increasing the Capability of Scientific Data Analysis Pipelines by

    Office of Scientific and Technical Information (OSTI)

    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 Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing BacteriaConnect Collidertransfer (Journal Article) | SciTechFLARESUsing Efficient

  9. Selective hydrocracking of raffinates

    SciTech Connect (OSTI)

    Shipikin, V.V.; Georgievskii, V.Yu.

    1987-05-01

    The most acceptable method for processing raffinates to improve their antiknock properties is selective hydrocracking. As a result of selective cracking of the straight-chain paraffinic hydrocarbons present in raffinates, an octane number gain of 15-20 may be achieved. The authors list certain process indexes for selective hydrocracking of 62-105/sup 0/C cut (benzene-toluene) and 105-140/sup 0/C cut (xylene). It is shown that the improvement of the antiknock properties of raffinates by selective hydrocracking may change the structure of automotive gasoline production quite substantially.

  10. arXiv:astro-ph/0512628v229Dec2005 Multiwavelength Observations of the Blazar Mrk 421 in

    E-Print Network [OSTI]

    , Tanta, Egypt 3 Department of Physics, University of Massachussetts, Amherst, MA 01003-4525, USA 4 School the time averaged spectrum can be fitted with a single power law of photon in- dex = 2.8 from dN/dE E

  11. SpanDex: Secure Password Tracking for Android Landon P. Cox

    E-Print Network [OSTI]

    Cox, Landon

    University Geoffrey Lawler Duke University Valentin Pistol Duke University Ali Razeen Duke University Bi Wu

  12. CONTRACTNO.: DE-X13-96GJ87335 TASK ORDER NO.: h

    Office of Legacy Management (LM)

    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 Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield Municipal Gas &SCE-SessionsSouth DakotaRobbins and700, 1. .&. 'explainsBurrell,C:^_. . _March

  13. CoDEx Project: A Hardware/Software Codesign Environment for the Exascale

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room News PublicationsAuditsCluster Compatibility Mode Cluster Compatibility Mode EdisonMarch

  14. CELLULAR METABOLISM AND APOPTOSIS DEXAMETHASONE, A PROMISING NEW CANDIDATE TO INTERVENE ON THE METABOLIC LEVEL

    E-Print Network [OSTI]

    DEX has been shown to modify metabolic pathways (in particular, anaplerosis and gluconeogenesis) both

  15. The oxygen abundance distribution in M101

    E-Print Network [OSTI]

    L. S. Pilyugin

    2001-05-07

    The well-observed spiral galaxy M101 was considered. The radial distributions of oxygen abundances determined in three different ways (with the classic Te - method, with the R23 - method, and with the P -- method) were compared. It was found that the parameters (the central oxygen abundance and the gradient) of the radial O/H(P) abundance distribution are close to those of the O/H(Te) abundance distribution. The parameters of the O/H(R23) abundance distribution differ significantly from those of the O/H(Te) abundance distribution: the central O/H(R23) oxygen abundance is higher by around 0.4dex and the gradient is steeper by a factor of around 1.5 as compared to those values in the O/H(Te) abundance distribution. The dispersion in O/H(P) abundance at fixed radius is rather small, around 0.08 dex, and is equal to that in O/H(Te) abundance. The dispersion in O/H(R23) abundance at fixed radius is appreciably larger, around 0.16 dex, compared to that in O/H(Te) abundance. It has been shown that the extra dispersion in O/H(R23) abundances is an artifact and reflects scatter in excitation parameter P at fixed radius.

  16. Chemical Homogeneity in Collinder 261 and Implications for Chemical Tagging

    E-Print Network [OSTI]

    G. M. De Silva; K. C. Freeman; M. Asplund; J. Bland-Hawthorn; M. S. Bessell; R. Collet

    2006-11-28

    This paper presents abundances for 12 red giants of the old open cluster Collinder 261 based on spectra from VLT/UVES. Abundances were derived for Na, Mg, Si, Ca, Mn, Fe, Ni, Zr and Ba. We find the cluster has a solar-level metallicity of [Fe/H] = -0.03 dex. However some alpha elements were found to be enhanced. The star-to-star scatter was consistent with the expected measurement uncertainty for all elements. The observed rms scatter is as follows: Na = 0.07, Mg = 0.05, Si = 0.06, Ca = 0.05, Mn = 0.03, Fe = 0.02, Ni = 0.04, Zr = 0.12, and Ba = 0.03 dex. The intrinsic scatter was estimated to be less than 0.05 dex. Such high levels of homogeneity indicate that chemical information remains preserved in this old open cluster. We use the chemical homogeneity we have now established in Cr 261, Hyades and the HR1614 moving group to examine the uniqueness of the individual cluster abundance patterns, ie. chemical signatures. We demonstrate that the three studied clusters have unique chemical signatures, and discuss how other such signatures may be searched for in the future. Our findings support the prospect of chemically tagging disk stars to common formation sites in order to unravel the dissipative history of the Galactic disk.

  17. On the lithium dip in the metal poor open cluster NGC 2243

    SciTech Connect (OSTI)

    François, P. [GEPI, Paris-Meudon Observatory, 61 Avenue de l'Observatoire, F-75014 Paris (France); Pasquini, L.; Palsa, R. [ESO, European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München (Germany); Biazzo, K. [INAF, Capodimonte Astronomical Observatory, via Moiariello 16, 80131 Naples (Italy); Bonifacio, P. [GEPI, Paris-Meudon Observatory, Place Jules Janssen 92190, Meudon (France)

    2014-05-02

    Lithium is a key element for studying the mixing mechanisms operating in stellar interiors. It can also be used to probe the chemical evolution of the Galaxy and the Big Bang nucleosynthesis. Measuring the abundance of Lithium in stars belonging to Open Clusters (hereafter OC) allows a detailed comparison with stellar evolutionary models. NGC 2243 is particularly interesting thanks to its relative low metallicity ([Fe/H]=?0.54 ± 0.10 dex). We performed a detailed analysis of high-resolution spectra obtained with the multi-object facility FLAMES at the VLT 8.2m telescope. Lithium abundance has been measured in 27 stars. We found a Li dip center of 1.06 M{sub ?}, which is significantly smaller than that observed in solar metallicity and metal-rich clusters. This finding confirms and strengthens the conclusion that the mass of the stars in the Li dip strongly depends on stellar metallicity. The mean Li abundance of the cluster is log n(Li) = 2.70 dex, which is substantially higher than that observed in 47 Tue. We derived an iron abundance of [Fe/H]=?0.54±0.10 dex for NGC 2243, in agreement (within the errors) with previous findings.

  18. The Role of Angiopoietin-like 4 in Lipid Homeostasis

    E-Print Network [OSTI]

    Gray, Nora

    2012-01-01

    DEX: dexamethasone DEXA: dual energy X-ray absorptiometryand scanned by dual-energy X-ray absorptiometry (DEXA) with

  19. The distribution of atomic hydrogen in EAGLE galaxies: morphologies, profiles, and HI holes

    E-Print Network [OSTI]

    Bahe, Yannick M; Kauffmann, Guinevere; Bower, Richard G; Schaye, Joop; Furlong, Michelle; Lagos, Claudia; Schaller, Matthieu; Trayford, James W; Vecchia, Claudio Dalla; Theuns, Tom

    2015-01-01

    We compare the mass and internal distribution of atomic hydrogen (HI) in 2200 present-day central galaxies with M_star > 10^10 M_Sun from the 100 Mpc EAGLE Reference simulation to observational data. Atomic hydrogen fractions are corrected for self-shielding using a fitting formula from radiative transfer simulations and for the presence of molecular hydrogen using an empirical or a theoretical prescription from the literature. The resulting neutral hydrogen fractions, M_(HI+H2)/M_star, agree with observations to better than 0.1 dex for galaxies with M_star between 10^10 and 10^11 M_Sun. Our fiducial, empirical H2 model based on gas pressure results in galactic HI mass fractions, M_HI/M_star, that agree with observations from the GASS survey to better than 0.3 dex, but the alternative theoretical H2 formula leads to a negative offset in M_HI/M_star of up to 0.5 dex. Visual inspection reveals that most HI disks in simulated HI-rich galaxies are vertically disturbed, plausibly due to recent accretion events. Ma...

  20. Properties of a Proper-Motion Selected Sample of Giants in the Small Magellanic Cloud near NGC 121

    E-Print Network [OSTI]

    Nicholas B. Suntzeff; Alistair R. Walker; Verne V. Smith; Robert P. Kraft; Arnold Klemola; Peter B. Stetson

    1998-09-28

    We present both low and high-dispersion abundance analyses of giants drawn from the zero proper motion sample near NGC 121. For the sample of 35 stars, the mean metallicity of the SMC field near NGC 121 is [Fe/H]=-1.3 with a real dispersion of 0.4 dex. The most metal-rich stars are at -0.5 dex and the most metal-poor stars at -2.1 dex. The velocity dispersion of the sample is 25 km/s. The dispersion of various kinematic samples in the SMC is independent of age. The RGB colors are consistent with Galactic globular clusters of similar metallicity. The field population, however, does not have an extended blue horizontal branch, and the main sequence turnoff extends 1 magnitude brighter than the turnoff in M5. Evidently active star formation in this region started roughly at the age of the Galactic globular cluster M5 and extended for about 6 Gyrs, and then stopped.

  1. Mass assembly in quiescent and star-forming galaxies since z=4 from UltraVISTA

    E-Print Network [OSTI]

    Ilbert, O; Fevre, O Le; Capak, P; Dunlop, J; Arnouts, S; Aussel, H; Caputi, K; Comparat, J; Guo, Q; Hudelot, P; Kartaltepe, J; Kneib, J P; Krogager, J K; Floc'h, E Le; Lilly, S; Mellier, Y; Milvang-Jensen, B; Moutard, T; Onodera, M; Renzini, M A; Richard, J; Salvato, M; Sanders, D B; Scoville, N; Silverman, J; Taniguchi, Y; Tasca, L; Thomas, R; Toft, S; Tresse, L; Vergani, D; Wolk, M; Zirm, A

    2013-01-01

    We estimate the galaxy stellar mass function and stellar mass density for star-forming and quiescent galaxies with 0.210^(10.7-10.9) Msun, while the rapid evolution at the low mass end is explained by the evolution of the specific star formation rate. By deriving the global stellar mass density, we show that galaxies grow in mass twice as quickly at 1dex than the cosmic star formation rate integrated over cosmic time. For the mass function of the quiescent galaxies, we do not find any significant evolution of the high-mass end at z<1, while however we observe a clear flattening of the faint-end slope. From z~3 to z~1, the density of quiescent galaxies increases over the entire mass range. Their comoving stellar mass density increases by 1.5 dex between z~3 and z~1 and by less than 0.2 dex at z<1. Finally, we compare our results with the semi-analytical model and find that they overestimate the density ...

  2. Vaporizer design criteria for ethanol fueled internal combustion engines 

    E-Print Network [OSTI]

    Ariyaratne, Arachchi Rallage

    1985-01-01

    to gasoline. Rogowski and Taylor (1941) showed that alcohol could be used as an anti-knock agent for gasoline, but that alcohol could not compete economically with petroleum fuels as an engine fuel. These and many other studies show the potential... been identified in conversion of diesel engines of farm tractors for using alcohol fuels. Distillation at atmospheric pressure does not yield 200 proof ethanol, (Winston, 1981), so with present technology, ethanol produced on farms is aqueous. A...

  3. Post-transcriptional regulation of gene expression by the DExD/H-box protein Dhh1

    E-Print Network [OSTI]

    Carroll, Johanna Shumway

    2011-01-01

    Cell. 125:1095-1109. van Dijk, E. , N. Cougot, S. Meyer, S.Embo J. 21:6915-24. van Dijk, E.L. , J.S. Sussenbach, andand Parker, 2003; van Dijk et al. , 2002). And, proteins

  4. Post-transcriptional regulation of gene expression by the DExD/H-box protein Dhh1

    E-Print Network [OSTI]

    Carroll, Johanna Shumway

    2011-01-01

    M.P. Spiller, and J.D. Beggs. 2008. A role for Q/N-richMayes, P. Lennertz, J.D. Beggs, and R. Parker. 2000. YeastMayes, P. Lennertz, J.D. Beggs, and R. Parker. 2000. Yeast

  5. Localization lengths for Schroedinger operators on Z^2 with decaying random potentials

    E-Print Network [OSTI]

    Thomas Chen

    2005-10-26

    We study a class of Schr\\"odinger operators on $\\Z^2$ with a random potential decaying as $|x|^{-\\dex}$, $00$. These estimates "interpolate" between the lower bound $\\lambda^{-2+\\eta}$ due to recent work of Schlag-Shubin-Wolff for $\\dex=0$, and pure a.c. spectrum for $\\dex>\\frac12$ demonstrated in recent work of Bourgain.

  6. NO HEAVY-ELEMENT DISPERSION IN THE GLOBULAR CLUSTER M92

    SciTech Connect (OSTI)

    Cohen, Judith G., E-mail: jlc@astro.caltech.edu [Palomar Observatory, Mail Stop 249-17, California Institute of Technology, Pasadena, CA 91125 (United States)

    2011-10-20

    Although there have been recent claims that there is a large dispersion in the abundances of the heavy neutron capture elements in the old Galactic globular cluster M92, we show that the measured dispersion for the absolute abundances of four of the rare earth elements within a sample of 12 luminous red giants in M92 ({<=}0.07 dex) does not exceed the relevant sources of uncertainty. As expected from previous studies, the heavy elements show the signature of the r-process. Their abundance ratios are essentially identical to those of M30, another nearby globular cluster of similar metallicity.

  7. The snow line in viscous disks around low-mass stars: implications for water delivery to terrestrial planets in the habitable zone

    E-Print Network [OSTI]

    Mulders, Gijs D; Min, Michiel; Pascucci, Ilaria

    2015-01-01

    The water ice or snow line is one of the key properties of protoplanetary disks that determines the water content of terrestrial planets in the habitable zone. Its location is determined by the properties of the star, the mass accretion rate through the disk, and the size distribution of dust suspended in the disk. We calculate the snow line location from recent observations of mass accretion rates and as a function of stellar mass. By taking the observed dispersion in mass accretion rates as a measure of the dispersion in initial disk mass, we find that stars of a given mass will exhibit a range of snow line locations. At a given age and stellar mass, the observed dispersion in mass accretion rates of 0.4 dex naturally leads to a dispersion in snow line locations of 0.2 dex. For ISM-like dust sizes, the one-sigma snow line location among solar mass stars of the same age ranges from 2 to 5 au. For more realistic dust opacities that include larger grains, the snow line is located up to two times closer to the ...

  8. Evidence for a metal-poor population in the inner Galactic Bulge

    E-Print Network [OSTI]

    Schultheis, M; Zasowski, G; Pérez, A E García; Sellgren, K; Smith, V; García-Hernández, D A; Zamora, O; Fritz, T K; Anders, F; Prieto, C Allende; Bizyaev, D; Kinemuchi, K; Pan, K; Malanushenko, E; Malanushenko, V; Shetrone, M D

    2015-01-01

    The inner Galactic Bulge has, until recently, been avoided in chemical evolution studies due to extreme extinction and stellar crowding. Large, near-IR spectroscopic surveys, such as APOGEE, allow for the first time the measurement of metallicities in the inner region of our Galaxy. We study metallicities of 33 K/M giants situated in the Galactic Center region from observations obtained with the APOGEE survey. We selected K/M giants with reliable stellar parameters from the APOGEE/ASPCAP pipeline. Distances, interstellar extinction values, and radial velocities were checked to confirm that these stars are indeed situated in the inner Galactic Bulge. We find a metal-rich population centered at [M/H] = +0.4 dex, in agreement with earlier studies of other bulge regions, but also a peak at low metallicity around $\\rm [M/H] = -1.0\\,dex$, suggesting the presence of a metal-poor population which has not previously been detected in the central region. Our results indicate a dominant metal-rich population with a metal...

  9. Galaxies in X-ray Selected Clusters and Groups in Dark Energy Survey Data: Stellar Mass Growth of Bright Central Galaxies Since z~1.2

    E-Print Network [OSTI]

    Zhang, Y; Mckay, T; Rooney, P; Evrard, A E; Romer, A K; Perfecto, R; Song, J; Desai, S; Mohr, J; Wilcox, H; Bermeo, A; Jeltema, T; Hollowood, D; Bacon, D; Capozzi, D; Collins, C; Das, R; Gerdes, D; Hennig, C; Hilton, M; Hoyle, B; Kay, S; Liddle, A; Mann, R G; Mehrtens, N; Nichol, R C; Papovich, C; Sahlén, M; Soares-Santos, M; Stott, J; Viana, P T; Abbott, T; Abdalla, F B; Banerji, M; Bauer, A H; Benoit-Lévy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Rosell, A Carnero; Castander, F J; Diehl, H T; Doel, P; Cunha, C E; Eifler, T F; Neto, A Fausti; Fernandez, E; Flaugher, B; Fosalba, P; Frieman, J; Gaztanaga, E; Gruen, D; Gruendl, R A; Honscheid, K; James, D; Kuehn, K; Kuropatkin, N; Lahav, O; Maia, M A G; Makler, M; Marshall, J L; Martini, Paul; Miquel, R; Ogando, R; Plazas, A A; Roodman, A; Rykoff, E S; Sako, M; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla, I; Smith, R C; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Tucker, D; Vikram, V; Da Costa, L N

    2015-01-01

    Using the science verification data of the Dark Energy Survey (DES) for a new sample of 106 X-Ray selected clusters and groups, we study the stellar mass growth of Bright Central Galaxies (BCGs) since redshift 1.2. Compared with the expectation in a semi-analytical model applied to the Millennium Simulation, the observed BCGs become under-massive/under-luminous with decreasing redshift. We incorporate the uncertainties associated with cluster mass, redshift, and BCG stellar mass measurements into analysis of a redshift-dependent BCG-cluster mass relation, $m_{*}\\propto(\\frac{M_{200}}{1.5\\times 10^{14}M_{\\odot}})^{0.24\\pm 0.08}(1+z)^{-0.19\\pm0.34}$, and compare the observed relation to the simulation prediction. We estimate the average growth rate since z = 1.0 for BCGs hosted by clusters of $M_{200, z}=10^{13.8}M_{\\odot}$, at $z=1.0$: $m_{*, BCG}$ appears to have grown by $0.13\\pm0.11$ dex, in tension at $\\sim 2.5 \\sigma$ significance level with the 0.4 dex growth rate expected in the simulation. We show that...

  10. THE METALLICITY DEPENDENCE OF THE CEPHEID P – L RELATION IN M101

    SciTech Connect (OSTI)

    Mager, Violet A.; Madore, Barry F.; Freedman, Wendy L., E-mail: mager@susqu.edu, E-mail: barry@obs.carnegiescience.edu, E-mail: wendy@obs.carnegiescience.edu [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2013-11-01

    The impact of metallicity on the Cepheid period-luminosity (P – L) relation is investigated using Hubble Space Telescope Advanced Camera for Surveys V and I images of M101. Variations in the reddening-free Wesenheit parameter (W), which is employed as a proxy for luminosity, are examined as a function of the radial distance from the center of M101 (and thus metallicity). We determine that there is no dependence of the slope on metallicity. However, the intercept is found to depend on metallicity by ?{sub VI} = –0.33 ± 0.12 mag dex{sup –1} and ?{sub VI} = –0.71 ± 0.17 mag dex{sup –1} using 2? and 3? rejection criteria, respectively. Sigma-clipping impacts the derived metallicity dependence, and the 2? criterion applied likely mitigates blending, particularly in the crowded inner regions of M101. A metallicity-corrected distance for M101 is obtained from 619 Cepheids (? = 28.96 ± 0.11), a result that agrees with the recently determined SN Ia distance. The metallicity effects described can be bypassed by working at near and mid-infrared wavelengths (e.g., the Carnegie Hubble Program)

  11. THE DISTRIBUTION OF THE ELEMENTS IN THE GALACTIC DISK. III. A RECONSIDERATION OF CEPHEIDS FROM l = 30{sup 0} TO 250{sup 0}

    SciTech Connect (OSTI)

    Luck, R. Earle [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106-7215 (United States); Lambert, David L., E-mail: luck@fafnir.astr.cwru.edu, E-mail: dll@astro.as.utexas.edu [McDonald Observatory, University of Texas at Austin, Austin, TX 78712 (United States)

    2011-10-15

    This paper reports on the spectroscopic investigation of 238 Cepheids in the northern sky. Of these stars, about 150 are new to the study of the galactic abundance gradient. These new Cepheids bring the total number of Cepheids involved in abundance distribution studies to over 400. In this work, we also consider systematics between various studies and also those which result from the choice of models. We find that systematic variations exist at the 0.06 dex level both between studies and model atmospheres. In order to control the systematic effects our final gradients depend only on abundances derived herein. A simple linear fit to the Cepheid data from 398 stars yields a gradient d[Fe/H]/dR{sub G} = -0.062 {+-} 0.002 dex kpc{sup -1} which is in good agreement with previously determined values. We have also re-examined the region of the 'metallicity island' of Luck et al. With the doubling of the sample in that region and our internally consistent abundances, we find that there is scant evidence for a distinct island. We also find in our sample the first reported Cepheid (V1033 Cyg) with a pronounced Li feature. The Li abundance is consistent with the star being on its redward pass toward the first giant branch.

  12. NON-LOCAL THERMODYNAMICAL EQUILIBRIUM EFFECTS ON THE IRON ABUNDANCE OF ASYMPTOTIC GIANT BRANCH STARS IN 47 TUCANAE

    SciTech Connect (OSTI)

    Lapenna, E.; Mucciarelli, A.; Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.; Massari, D. [Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Origlia, L. [INAF- Osservatorio Astronomico di Bologna, Via Ranzani, 1, 40127 Bologna (Italy)

    2014-12-20

    We present the iron abundance of 24 asymptotic giant branch (AGB) stars, members of the globular cluster 47 Tucanae, obtained with high-resolution spectra collected with the FEROS spectrograph at the MPG/ESO 2.2 m Telescope. We find that the iron abundances derived from neutral lines (with a mean value [Fe I/H] =–0.94 ± 0.01, ? = 0.08 dex) are systematically lower than those derived from single ionized lines ([Fe II/H] =–0.83 ± 0.01, ? = 0.05 dex). Only the latter are in agreement with those obtained for a sample of red giant branch (RGB) cluster stars, for which the Fe I and Fe II lines provide the same iron abundance. This finding suggests that non-local thermodynamical equilibrium (NLTE) effects driven by overionization mechanisms are present in the atmosphere of AGB stars and significantly affect the Fe I lines while leaving Fe II features unaltered. On the other hand, the very good ionization equilibrium found for RGB stars indicates that these NLTE effects may depend on the evolutionary stage. We discuss the impact of this finding on both the chemical analysis of AGB stars and on the search for evolved blue stragglers.

  13. Gustav Update

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

    Beam is available to users according to normal schedule. The Quintel machine in the cleanroom and the DEX scanner-controller computers in the Experiment Hall were malfunctioning,...

  14. J Comp Physiol B DOI 10.1007/s00360-008-0314-4

    E-Print Network [OSTI]

    Krebs, Charles J.

    cortex secretes glucocorticoids to aid in daily functions such as the regulation of energy storage (EIA) · Adrenocorticotropic hormone (ACTH) · Dexamethasone (DEX) · Predation risk · Diurnal rhythm

  15. Stellar populations in the Phoenix dwarf galaxy

    E-Print Network [OSTI]

    Enrico V. Held; Ivo Saviane; Yazan Momany

    1999-03-01

    We have obtained deep BVI CCD photometry of Phoenix, a galaxy considered a transition case between dwarf spheroidal and dwarf irregular galaxies. A comparison of our data with the RGBs of Galactic globular clusters gives a mean metal abundance [Fe/H] = -1.81+/-0.10 dex. The presence of an intrinsic color dispersion in the upper red RGB suggests an abundance range of about 0.5 dex, although a range in age may also affect the RGB width. For the first time, a HB has been revealed at V~23.8. The HB is predominantly red yet moderately extended to the blue, which indicates the presence of a significant population with age comparable to that of old halo GGCs. This HB morphology in a metal-poor system indicates a mild "second parameter" effect. From the mean level of the HB we derived a true distance modulus 23.21+/-0.08, in good agreement with the distance modulus 23.04+/-0.07 estimated from the cutoff of the RGB at I~23.1. We find a radial gradient in the HB morphology, and our CMDs show a small number of stars above the RGB tip, that most likely are AGB stars of an intermediate age population. Their number indicates that the fraction of intermediate age population in Phoenix is approximately 30-40%. A young stellar population is definitely present in Phoenix, consistent with a star formation episode started at least 0.6 Gyr ago, up to 1x10^{8} yr ago. Both young stars and AGB stars are centrally concentrated, which indicates that recent star formation preferentially occurred in the inner galaxy regions. In many respects, Phoenix appears not dissimilar from dwarf spheroidal galaxies in the Local Group.

  16. Hemocompatibility and biocompatibility of antibacterial biomimetic hybrid films

    SciTech Connect (OSTI)

    Coll Ferrer, M. Carme; Eckmann, Uriel N.; Composto, Russell J.; Eckmann, David M.

    2013-11-01

    In previous work, we developed novel antibacterial hybrid coatings based on dextran containing dispersed Ag NPs (? 5 nm, DEX-Ag) aimed to offer dual protection against two of the most common complications associated with implant surgery, infections and rejection of the implant. However, their blood-material interactions are unknown. In this study, we assess the hemocompatibility and biocompatibility of DEX-Ag using fresh blood and two cell lines of the immune system, monocytes (THP-1 cells) and macrophages (PMA-stimulated THP-1 cells). Glass, polyurethane (PU) and bare dextran (DEX) were used as reference surfaces. PU, DEX and DEX-Ag exhibited non-hemolytic properties. Relative to glass (100%), platelet attachment on PU, DEX and DEX-Ag was 15%, 10% and 34%, respectively. Further, we assessed cell morphology and viability, pro-inflammatory cytokines expression (TNF-? and IL-1?), pro-inflammatory eicosanoid expression (Prostaglandin E{sub 2}, PGE{sub 2}) and release of reactive oxygen species (ROS, superoxide and H{sub 2}O{sub 2}) following incubation of the cells with the surfaces. The morphology and cell viability of THP-1 cells were not affected by DEX-Ag whereas DEX-Ag minimized spreading of PMA-stimulated THP-1 cells and caused a reduction in cell viability (16% relative to other surfaces). Although DEX-Ag slightly enhanced release of ROS, the expression of pro-inflammatory cytokines remained minimal with similar levels of PGE{sub 2}, as compared to the other surfaces studied. These results highlight low toxicity of DEX-Ag and hold promise for future applications in vivo. - Highlights: • We examined specific blood-contact reactions of dextran doped with Ag NPs coatings. • Biocompatibility was assessed with THP-1 cells and PMA-stimulated THP-1 cells. • Glass, polyurethane and dextran were used as reference surfaces. • Hybrid coatings exhibited non-hemolytic properties. • Low toxicity, inflammatory response and ROS suggest potential for in vivo use.

  17. Detailed abundances of planet-hosting wide binaries. I. Did planet formation imprint chemical signatures in the atmospheres of HD 20782/81?

    SciTech Connect (OSTI)

    Mack III, Claude E.; Stassun, Keivan G.; Schuler, Simon C.; Norris, John

    2014-06-01

    Using high-resolution, high signal-to-noise echelle spectra obtained with Magellan/MIKE, we present a detailed chemical abundance analysis of both stars in the planet-hosting wide binary system HD 20782 + HD 20781. Both stars are G dwarfs, and presumably coeval, forming in the same molecular cloud. Therefore we expect that they should possess the same bulk metallicities. Furthermore, both stars also host giant planets on eccentric orbits with pericenters ?0.2 AU. Here, we investigate if planets with such orbits could lead to the host stars ingesting material, which in turn may leave similar chemical imprints in their atmospheric abundances. We derived abundances of 15 elements spanning a range of condensation temperature, T {sub C} ? 40-1660 K. The two stars are found to have a mean element-to-element abundance difference of 0.04 ± 0.07 dex, which is consistent with both stars having identical bulk metallicities. In addition, for both stars, the refractory elements (T {sub C} >900 K) exhibit a positive correlation between abundance (relative to solar) and T {sub C}, with similar slopes of ?1×10{sup –4} dex K{sup –1}. The measured positive correlations are not perfect; both stars exhibit a scatter of ?5×10{sup –5} dex K{sup –1} about the mean trend, and certain elements (Na, Al, Sc) are similarly deviant in both stars. These findings are discussed in the context of models for giant planet migration that predict the accretion of H-depleted rocky material by the host star. We show that a simple simulation of a solar-type star accreting material with Earth-like composition predicts a positive—but imperfect—correlation between refractory elemental abundances and T {sub C}. Our measured slopes are consistent with what is predicted for the ingestion of 10-20 Earths by each star in the system. In addition, the specific element-by-element scatter might be used to distinguish between planetary accretion and Galactic chemical evolution scenarios.

  18. Nitrogen Production in Starburst Galaxies Detected by GALEX

    E-Print Network [OSTI]

    Ryan P. Mallery; Lisa Kewley; R. Michael Rich; Samir Salim; Stephane Charlot; Christy Tremonti; Mark Seibert; Todd Small; Ted Wyder; Tom A. Barlow; Karl Forster; Peter G. Friedman; D. Christopher Martin; Patrick Morrissey; Susan G. Neff; David Schiminovich; Luciana Bianchi; Jose Donas; Timothy Heckman; Young-Wook Lee; Barry F. Madore; Bruno Milliard; Alex S. Szalay; Barry Y. Welsh; Suk Young Yi

    2007-06-29

    We investigate the production of nitrogen in star forming galaxies with ultraviolet (UV) radiation detected by the Galaxy Evolution Explorer Satellite (GALEX). We use a sample of 8,745 GALEX emission line galaxies matched to the Sloan Digital Sky Survey (SDSS) spectroscopic sample. We derive both gas-phase oxygen and nitrogen abundances for the sample, and apply stellar population synthesis models to derive stellar masses and star formation histories of the galaxies. We compare oxygen abundances derived using three different diagnostics. We derive the specific star formation rates of the galaxies by modeling the 7-band GALEX+SDSS photometry. We find that galaxies that have log SFR/M$_*$ > -10.0 typically have values of log N/O ~0.05 dex less than galaxies with log SFR/M$_*$ < -10.0 and similar oxygen abundances.

  19. THE APOKASC CATALOG: AN ASTEROSEISMIC AND SPECTROSCOPIC JOINT SURVEY OF TARGETS IN THE KEPLER FIELDS

    SciTech Connect (OSTI)

    Pinsonneault, Marc H.; Epstein, Courtney; Johnson, Jennifer A. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Elsworth, Yvonne; Chaplin, William J. [University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT (United Kingdom); Hekker, Saskia; Silva Aguirre, Victor; Stello, Dennis [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Mészáros, Sz. [Astronomy Department, Indiana University, Bloomington, IN 47405 (United States); García, Rafael A.; Beck, Paul [Laboratoire AIM, CEA/DSM-CNRS—Université Denis Diderot-IRFU/SAp, F-91191 Gif-sur-Yvette Cedex (France); Holtzman, Jon [Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003 (United States); Mathur, Savita [Space Science Institute, 4750 Walnut street, Suite 205, Boulder, CO 80301 (United States); García Pérez, Ana [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Girardi, Léo [Osservatorio Astronomico di Padova—INAF, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy); Basu, Sarbani [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Shetrone, Matthew [University of Texas at Austin, McDonald Observatory, 32 Fowlkes Road, TX 79734-3005 (United States); Allende Prieto, Carlos [Instituto de Astrofsica de Canarias (IAC), C/Va Lactea, s/n, E-38200 La Laguna, Tenerife (Spain); An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul (Korea, Republic of); Beers, Timothy C., E-mail: pinsonneault.1@osu.edu [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46656 (United States); and others

    2015-01-01

    We present the first APOKASC catalog of spectroscopic and asteroseismic properties of 1916 red giants observed in the Kepler fields. The spectroscopic parameters provided from the Apache Point Observatory Galactic Evolution Experiment project are complemented with asteroseismic surface gravities, masses, radii, and mean densities determined by members of the Kepler Asteroseismology Science Consortium. We assess both random and systematic sources of error and include a discussion of sample selection for giants in the Kepler fields. Total uncertainties in the main catalog properties are of the order of 80 K in T {sub eff}, 0.06 dex in [M/H], 0.014 dex in log g, and 12% and 5% in mass and radius, respectively; these reflect a combination of systematic and random errors. Asteroseismic surface gravities are substantially more precise and accurate than spectroscopic ones, and we find good agreement between their mean values and the calibrated spectroscopic surface gravities. There are, however, systematic underlying trends with T {sub eff} and log g. Our effective temperature scale is between 0 and 200 K cooler than that expected from the infrared flux method, depending on the adopted extinction map, which provides evidence for a lower value on average than that inferred for the Kepler Input Catalog (KIC). We find a reasonable correspondence between the photometric KIC and spectroscopic APOKASC metallicity scales, with increased dispersion in KIC metallicities as the absolute metal abundance decreases, and offsets in T {sub eff} and log g consistent with those derived in the literature. We present mean fitting relations between APOKASC and KIC observables and discuss future prospects, strengths, and limitations of the catalog data.

  20. ELEMENTAL ABUNDANCE RATIOS IN STARS OF THE OUTER GALACTIC DISK. IV. A NEW SAMPLE OF OPEN CLUSTERS

    SciTech Connect (OSTI)

    Yong, David; Carney, Bruce W.; Friel, Eileen D. E-mail: bruce@physics.unc.edu

    2012-10-01

    We present radial velocities and chemical abundances for nine stars in the old, distant open clusters Be18, Be21, Be22, Be32, and PWM4. For Be18 and PWM4, these are the first chemical abundance measurements. Combining our data with literature results produces a compilation of some 68 chemical abundance measurements in 49 unique clusters. For this combined sample, we study the chemical abundances of open clusters as a function of distance, age, and metallicity. We confirm that the metallicity gradient in the outer disk is flatter than the gradient in the vicinity of the solar neighborhood. We also confirm that the open clusters in the outer disk are metal-poor with enhancements in the ratios [{alpha}/Fe] and perhaps [Eu/Fe]. All elements show negligible or small trends between [X/Fe] and distance (<0.02 dex kpc{sup -1}), but for some elements, there is a hint that the local (R{sub GC} < 13 kpc) and distant (R{sub GC} > 13 kpc) samples may have different trends with distance. There is no evidence for significant abundance trends versus age (<0.04 dex Gyr{sup -1}). We measure the linear relation between [X/Fe] and metallicity, [Fe/H], and find that the scatter about the mean trend is comparable to the measurement uncertainties. Comparison with solar neighborhood field giants shows that the open clusters share similar abundance ratios [X/Fe] at a given metallicity. While the flattening of the metallicity gradient and enhanced [{alpha}/Fe] ratios in the outer disk suggest a chemical enrichment history different from that of the solar neighborhood, we echo the sentiments expressed by Friel et al. that definitive conclusions await homogeneous analyses of larger samples of stars in larger numbers of clusters. Arguably, our understanding of the evolution of the outer disk from open clusters is currently limited by systematic abundance differences between various studies.

  1. Detailed abundances for a large sample of giant stars in the globular cluster 47 Tucanae (NGC 104)

    SciTech Connect (OSTI)

    Cordero, M. J.; Pilachowski, C. A. [Astronomy Department, Indiana University Bloomington, Swain West 319, 727 East 3rd Street, Bloomington, IN 47405-7105 (United States); Johnson, C. I. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-15, Cambridge, MA 02138 (United States); McDonald, I.; Zijlstra, A. A. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, Manchester M13 9PL (United Kingdom); Simmerer, J., E-mail: majocord@indiana.edu, E-mail: catyp@astro.indiana.edu, E-mail: cjohnson@cfa.harvard.edu, E-mail: mcdonald@jb.man.ac.uk, E-mail: albert.zijlstra@manchester.ac.uk, E-mail: jennifer@physics.utah.edu [University of Utah, Physics and Astronomy, 115 South 1400 East #201, Salt Lake City, UT 84112-0830 (United States)

    2014-01-01

    47 Tuc is an ideal target to study chemical evolution and globular cluster (GC) formation in massive more metal-rich GCs, as it is the closest massive GC. We present chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu in 164 red giant branch stars in the massive GC 47 Tuc using spectra obtained with both the Hydra multifiber spectrograph at the Blanco 4 m telescope and the FLAMES multiobject spectrograph at the Very Large Telescope. We find an average [Fe/H] = –0.79 ± 0.09 dex, consistent with literature values, as well as overabundances of alpha-elements ([?/Fe] ? 0.3 dex). The n-capture process elements indicate that 47 Tuc is r process-dominated ([Eu/La] = +0.24), and the light elements O, Na, and Al exhibit star-to-star variations. The Na-O anticorrelation, a signature typically seen in Galactic GCs, is present in 47 Tuc, and extends to include a small number of stars with [O/Fe] ? –0.5. Additionally, the [O/Na] ratios of our sample reveal that the cluster stars can be separated into three distinct populations. A Kolmogorov-Smirnov test demonstrates that the O-poor/Na-rich stars are more centrally concentrated than the O-rich/Na-poor stars. The observed number and radial distribution of 47 Tuc's stellar populations, as distinguished by their light element composition, agrees closely with the results obtained from photometric data. We do not find evidence supporting a strong Na-Al correlation in 47 Tuc, which is consistent with current models of asymptotic giant branch nucleosynthesis yields.

  2. METAL ABUNDANCES, RADIAL VELOCITIES, AND OTHER PHYSICAL CHARACTERISTICS FOR THE RR LYRAE STARS IN THE KEPLER FIELD

    SciTech Connect (OSTI)

    Nemec, James M.; Cohen, Judith G.; Sesar, Branimir; Ripepi, Vincenzo; Derekas, Aliz; Moskalik, Pawel; Chadid, Merieme; Bruntt, Hans E-mail: jmn@isr.bc.ca E-mail: bsesar@astro.caltech.edu E-mail: derekas@konkoly.hu E-mail: chadid@marseille.fr

    2013-08-20

    Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude {delta} Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from -2.54 {+-} 0.13 (NR Lyr) to -0.05 {+-} 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] {approx}-0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P-{phi}{sub 31}{sup s}-[Fe/H] relationships are derived based on {approx}970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg)

  3. UV-TO-FIR ANALYSIS OF SPITZER/IRAC SOURCES IN THE EXTENDED GROTH STRIP. II. PHOTOMETRIC REDSHIFTS, STELLAR MASSES, AND STAR FORMATION RATES

    SciTech Connect (OSTI)

    Barro, G.; Perez-Gonzalez, P. G.; Gallego, J.; Villar, V.; Zamorano, J. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Kajisawa, M.; Yamada, T. [Astronomical Institute, Tohoku University, Aramaki, Aoba, Sendai 9808578 (Japan); Miyazaki, S. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

    2011-04-01

    Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Paper I), we present a detailed spectral energy distribution (SED) analysis of nearly 80,000 IRAC 3.6 + 4.5 {mu}m selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates (SFRs) separately for each galaxy in this large sample. The catalog includes 76,936 sources with [3.6] {<=} 23.75 (85% completeness level of the IRAC survey) over 0.48 deg{sup 2}. The typical photometric redshift accuracy is {Delta}z/(1 + z) = 0.034, with a catastrophic outlier fraction of just 2%. We quantify the systematics introduced by the use of different stellar population synthesis libraries and initial mass functions in the calculation of stellar masses. We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies, based on several sets of dust emission templates and SFR indicators. We evaluate the systematic differences and goodness of the different SFR estimations using the deep FIDEL 70 {mu}m data available in the Extended Groth Strip. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z {approx}> 1.5 observed when only MIPS 24 {mu}m data are available. All data products (SEDs, postage stamps from imaging data, and different estimations of the photometric redshifts, stellar masses, and SFRs of each galaxy) described in this and the companion paper are publicly available, and they can be accessed through our the Web interface utility Rainbow-navigator.

  4. REPRODUCING THE OBSERVED ABUNDANCES IN RCB AND HdC STARS WITH POST-DOUBLE-DEGENERATE MERGER MODELS-CONSTRAINTS ON MERGER AND POST-MERGER SIMULATIONS AND PHYSICS PROCESSES

    SciTech Connect (OSTI)

    Menon, Athira; Herwig, Falk; Denissenkov, Pavel A. [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P5C2 (Canada); Clayton, Geoffrey C.; Staff, Jan [Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Tower Dr., Baton Rouge, LA 70803-4001 (United States); Pignatari, Marco [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Paxton, Bill [Kavli Institute for Theoretical Physics and Department of Physics, Kohn Hall, University of California, Santa Barbara, CA 93106 (United States)

    2013-07-20

    The R Coronae Borealis (RCB) stars are hydrogen-deficient, variable stars that are most likely the result of He-CO WD mergers. They display extremely low oxygen isotopic ratios, {sup 16}O/{sup 18}O {approx_equal} 1-10, {sup 12}C/{sup 13}C {>=} 100, and enhancements up to 2.6 dex in F and in s-process elements from Zn to La, compared to solar. These abundances provide stringent constraints on the physical processes during and after the double-degenerate merger. As shown previously, O-isotopic ratios observed in RCB stars cannot result from the dynamic double-degenerate merger phase, and we now investigate the role of the long-term one-dimensional spherical post-merger evolution and nucleosynthesis based on realistic hydrodynamic merger progenitor models. We adopt a model for extra envelope mixing to represent processes driven by rotation originating in the dynamical merger. Comprehensive nucleosynthesis post-processing simulations for these stellar evolution models reproduce, for the first time, the full range of the observed abundances for almost all the elements measured in RCB stars: {sup 16}O/{sup 18}O ratios between 9 and 15, C-isotopic ratios above 100, and {approx}1.4-2.35 dex F enhancements, along with enrichments in s-process elements. The nucleosynthesis processes in our models constrain the length and temperature in the dynamic merger shell-of-fire feature as well as the envelope mixing in the post-merger phase. s-process elements originate either in the shell-of-fire merger feature or during the post-merger evolution, but the contribution from the asymptotic giant branch progenitors is negligible. The post-merger envelope mixing must eventually cease {approx}10{sup 6} yr after the dynamic merger phase before the star enters the RCB phase.

  5. Characterizing Pleiotropic Effects of Glucocorticoids in Mice Using Heavy Water Labeling and Mass Spectrometry

    E-Print Network [OSTI]

    Roohk, Donald Jason

    2011-01-01

    de novo lipogenesis: DNL; dual energy X-ray absorptiometry:analysis using dual energy X-ray absorptiometry (DEXA) andWT; dexamethasone: DEX; dual energy X-ray absorptiometry:

  6. Separation and concentration of lower alcohols from dilute aqueous solutions

    DOE Patents [OSTI]

    Moore, Raymond H. (Richland, WA); Eakin, David E. (Kennewick, WA); Baker, Eddie G. (Richland, WA); Hallen, Richard T. (Richland, WA)

    1991-01-01

    A process for producing, from a dilute aqueous solution of a lower (C.sub.1 -C.sub.5) alcohol, a concentrated liquid solution of the alcohol in an aromatic organic solvent is disclosed. Most of the water is removed from the dilute aqueous solution of alcohol by chilling sufficiently to form ice crystals. Simultaneously, the remaining liquid is extracted at substantially the same low temperature with a liquid organic solvent that is substantially immiscible in aqueous liquids and has an affinity for the alcohol at that temperature, causing the alcohol to transfer to the organic phase. After separating the organic liquid from the ice crystals, the organic liquid can be distilled to enrich the concentration of alcohol therein. Ethanol so separated from water and concentrated in an organic solvent such as toluene is useful as an anti-knock additive for gasoline.

  7. Vapor-liquid equilibrium for methanol + 1,1-dimethylpropyl methyl ether at (288.15, 308.15, and 328.15) K

    SciTech Connect (OSTI)

    Moessner, F.; Coto, B.; Pando, C.; Rubio, R.G.; Renuncio, J.A.R. [Universidad Complutense, Madrid (Spain). Departamento de Quimica Fisica 1] [Universidad Complutense, Madrid (Spain). Departamento de Quimica Fisica 1

    1996-05-01

    Oxygenated compounds are being used as additives to gasoline because of their antiknock effects. Vapor-liquid equilibria for methanol + 1,1-dimethylpropyl methyl ether (tert-amyl methyl ether or TAME) have been measured at (288.15, 308.15, and 328.15) K. A Gibbs-Van Ness type apparatus for total vapor pressure measurements has been used. The system shows positive deviations from Raoult`s law with an azeotrope, whose coordinates are reported at the three temperatures studied. Results have been analyzed in terms of the UNIQUAC model, several versions of the UNIFAC model, and the modified-Huron-Vidal second-order (MHV2) group contribution equation of state.

  8. Effects of Dexamethasone on Mesenchymal Stromal Cell Chondrogenesis and Aggrecanase Activity: Comparison of Agarose and Self-Assembling Peptide Scaffolds

    E-Print Network [OSTI]

    Florine, Emily Marie

    Objective: Dexamethasone (Dex) is a synthetic glucocorticoid that has pro-anabolic and anticatabolic effects in cartilage tissue engineering systems, though the mechanisms by which these effects are mediated are not well ...

  9. On the oxygen abundance in our Galaxy

    E-Print Network [OSTI]

    L. S. Pilyugin; F. Ferrini; R. V. Shkvarun

    2003-02-03

    The compilation of published spectra of Galactic HII regions with available diagnostic [OIII]4363 line has been carried out. Our list contains 71 individual measurements of 13 HII regions in the range of galactocentric distances from 6.6 to 14.8 kpc. The oxygen abundances in all the HII regions were recomputed in the same way, using the classic Te - method. The oxygen abundance at the solar galactocentric distance traced by those HII regions is in agreement with the oxygen abundance in the interstellar medium in the solar vicinity derived with high precision from the interstellar absorption lines towards stars. The derived radial oxygen abundance distribution was compared with that for HII regions from the Shaver et al. (1983) sample which is the basis of many models for the chemical evolution of our Galaxy. It was found that the original Shaver et al.'s oxygen abundances are overestimated by 0.2-0.3 dex. Oxygen abundances in HII regions from the Shaver et al. sample have been redetermined with the recently suggested P - method. The radial distribution of oxygen abundances from the Shaver et al. sample redetermined with the P - method is in agreement with our radial distribution of (O/H)_Te abundances.

  10. Lactoferrin inhibits dexamethasone-induced chondrocyte impairment from osteoarthritic cartilage through up-regulation of extracellular signal-regulated kinase 1/2 and suppression of FASL, FAS, and Caspase 3

    SciTech Connect (OSTI)

    Tu, Yihui [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China)] [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China); Xue, Huaming [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China) [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China); Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Francis, Wendy [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)] [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Davies, Andrew P. [Department of Orthopaedics and Trauma, Moriston Hospital, Swansea (United Kingdom)] [Department of Orthopaedics and Trauma, Moriston Hospital, Swansea (United Kingdom); Pallister, Ian; Kanamarlapudi, Venkateswarlu [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)] [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Xia, Zhidao, E-mail: zhidao.xia@gmail.com [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)] [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)

    2013-11-08

    Highlights: •Dex exerts dose-dependant inhibition of HACs viability and induction of apoptosis. •Dex-induced impairment of chondrocytes was attenuated by rhLF. •ERK and FASL/FAS signaling are involved in the effects of rhLF. •OA patients with glucocorticoid-induced cartilage damage may benefit from treatment with rhLF. -- Abstract: Dexamethasone (Dex) is commonly used for osteoarthritis (OA) with excellent anti-inflammatory and analgesic effect. However, Dex also has many side effects following repeated use over prolonged periods mainly through increasing apoptosis and inhibiting proliferation. Lactoferrin (LF) exerts significantly anabolic effect on many cells and little is known about its effect on OA chondrocytes. Therefore, the aim of this study is to investigate whether LF can inhibit Dex-induced OA chondrocytes apoptosis and explore its possible molecular mechanism involved in. MTT assay was used to determine the optimal concentration of Dex and recombinant human LF (rhLF) on chondrocytes at different time and dose points. Chondrocytes were then stimulated with Dex in the absence or presence of optimal concentration of rhLF. Cell proliferation and viability were evaluated using MTT and LIVE/DEAD assay, respectively. Cell apoptosis was evaluated by multi-parameter apoptosis assay kit using both confocal microscopy and flow cytometry, respectively. The expression of extracellular signal-regulated kinase (ERK), FAS, FASL, and Caspase-3 (CASP3) at the mRNA and protein levels were examined by real-time polymerase chain reaction (PCR) and immunocytochemistry, respectively. The optimal concentration of Dex (25 ?g/ml) and rhLF (200 ?g/ml) were chosen for the following experiments. rhLF significantly reversed the detrimental effect of Dex on chondrocytes proliferation, viability, and apoptosis. In addition, rhLF significantly prevented Dex-induced down-regulation of ERK and up-regulation of FAS, FASL, and CASP3. These findings demonstrated that rhLF acts as an anabolic effect on chondrocytes through significantly reversing Dex-induced chondrocytes apoptosis. This study may contribute to further investigating the clinical application of LF on OA.

  11. Alkaline tolerant dextranase from streptomyces anulatus

    DOE Patents [OSTI]

    Decker, Stephen R. (Berthoud, CO); Adney, William S. (Golden, CO); Vinzant, Todd B. (Golden, CO); Himmel, Michael E. (Littleton, CO)

    2003-01-01

    A process for production of an alkaline tolerant dextranase enzyme comprises culturing a dextran-producing microorganism Streptomyces anulatus having accession no. ATCC PTA-3866 to produce an alkaline tolerant dextranase, Dex 1 wherein the protein in said enzyme is characterized by a MW of 63.3 kDa and Dex 2 wherein its protein is characterized by a MW of 81.8 kDa.

  12. Gas Inflow and Metallicity Drops in Star-forming Galaxies

    E-Print Network [OSTI]

    Ceverino, Daniel; Muñoz-Tuñon, Casiana; Dekel, Avishai; Elmegreen, Bruce G; Elmegreen, Debra M; Primack, Joel

    2015-01-01

    Gas inflow feeds galaxies with low metallicity gas from the cosmic web, sustaining star formation across the Hubble time. We make a connection between these inflows and metallicity inhomogeneities in star-forming galaxies, by using synthetic narrow-band images of the Halpha emission line from zoom-in AMR cosmological simulations of galaxies with stellar masses of $M \\simeq 10^9 $Msun at redshifts z=2-7. In $\\sim$50\\% of the cases at redshifts lower than 4, the gas inflow gives rise to star-forming, Halpha-bright, off-centre clumps. Most of these clumps have gas metallicities, weighted by Halpha luminosity, lower than the metallicity in the surrounding interstellar medium by $\\sim$0.3 dex, consistent with observations of chemical inhomogeneities at high and low redshifts. Due to metal mixing by shear and turbulence, these metallicity drops are dissolved in a few disc dynamical times. Therefore, they can be considered as evidence for rapid gas accretion coming from cosmological inflow of pristine gas.

  13. The Origin of Fluorine: Abundances in AGB Carbon Stars Revisited

    E-Print Network [OSTI]

    Abia, C; Cristallo, S; de Laverny, P

    2015-01-01

    Revised spectroscopic parameters for the HF molecule and a new CN line list in the 2.3 mu region have been recently available, allowing a revision of the F content in AGB stars. AGB carbon stars are the only observationally confirmed sources of fluorine. Nowadays there is not a consensus on the relevance of AGB stars in its Galactic chemical evolution. The aim of this article is to better constrain the contribution of these stars with a more accurate estimate of their fluorine abundances. Using new spectroscopic tools and LTE spectral synthesis, we redetermine fluorine abundances from several HF lines in the K-band in a sample of Galactic and extragalactic AGB carbon stars of spectral types N, J and SC spanning a wide range of metallicities. On average, the new derived fluorine abundances are systematically lower by 0.33 dex with respect to previous determinations. This may derive from a combination of the lower excitation energies of the HF lines and the larger macroturbulence parameters used here as well as...

  14. Oxygen enrichment in carbon-rich planetary nebulae

    E-Print Network [OSTI]

    Delgado-Inglada, Gloria; Peimbert, Manuel; Stasi?ska, Gra?yna; Morisset, Christophe

    2015-01-01

    We study the relation between the chemical composition and the type of dust present in a group of 20 Galactic planetary nebulae (PNe) that have high quality optical and infrared spectra. The optical spectra are used, together with the best available ionization correction factors, to calculate the abundances of Ar, C, Cl, He, N, Ne, and O relative to H. The infrared spectra are used to classify the PNe in two groups depending on whether the observed dust features are representative of oxygen-rich or carbon-rich environments. The sample contains one object from the halo, eight from the bulge, and eleven from the local disc. We compare their chemical abundances with nucleosynthesis model predictions and with the ones obtained in seven Galactic H II regions of the solar neighbourhood. We find evidence of O enrichment (by $\\sim$ 0.3 dex) in all but one of the PNe with carbon-rich dust (CRD). Our analysis shows that Ar, and especially Cl, are the best metallicity indicators of the progenitors of PNe. There is a tig...

  15. Supermassive black holes with high accretion rates in active galactic nuclei. II. The most luminous standard candles in the universe

    SciTech Connect (OSTI)

    Wang, Jian-Min; Du, Pu; Hu, Chen; Qiu, Jie; Li, Yan-Rong [Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China); Netzer, Hagai; Kaspi, Shai [Wise Observatory, School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Bai, Jin-Ming; Wang, Fang [Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011, Yunnan (China); Lu, Kai-Xing [Astronomy Department, Beijing Normal University, Beijing 100875 (China); Collaboration: SEAMBH collaboration

    2014-10-01

    This is the second in a series of papers reporting on a large reverberation mapping (RM) campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). The goal is to identify super-Eddington accreting massive black holes (SEAMBHs) and to use their unique properties to construct a new method for measuring cosmological distances. Based on theoretical models, the saturated bolometric luminosity of such sources is proportional to the BH mass, which can be used to obtain their distance. Here we report on five new RM measurements and show that in four of the cases, we can measure the BH mass and three of these sources are SEAMBHs. Together with the three sources from our earlier work, we now have six new sources of this type. We use a novel method based on a minimal radiation efficiency to identify nine additional SEAMBHs from earlier RM-based mass measurements. We use a Bayesian analysis to determine the parameters of the new distance expression and the method uncertainties from the observed properties of the objects in the sample. The ratio of the newly measured distances to the standard cosmological ones has a mean scatter of 0.14 dex, indicating that SEAMBHs can be use as cosmological distance probes. With their high luminosity, long period of activity, and large numbers at high redshifts, SEAMBHs have a potential to extend the cosmic distance ladder beyond the range now explored by Type Ia supernovae.

  16. Effects of magnetic fields on lithium evolution in F and G stars

    SciTech Connect (OSTI)

    Li, T. D.; Bi, S. L.; Yang, W. M.; Liu, K.; Tian, Z. J.; Ge, Z. S., E-mail: litanda@mail.bnu.edu.cn, E-mail: bisl@bnu.edu.cn [Astronomy Department, Beijing Normal University, Beijing 100875 (China)

    2014-02-01

    To study the effects of magnetic fields on lithium depletion and to explain the characteristics of lithium evolution in F- and G-type stars in open clusters, we construct a stellar model that includes a Tayler-Spruit dynamo-type field. Through examining the features of extra-mixing caused by magnetic fields in stellar interiors and the relationship between lithium depletion and the input parameters (i.e., mass, metallicity, and the initial rotational condition), we find that the magnetic model produces extra-mixing processes different from other models. During pre-main sequence, the model exhibits very efficient extra-mixing, resulting in strong lithium depletion. As a star evolves, the efficiency of extra-mixing rapidly decreases and lithium depletion slows down at old ages. By setting up different initial rotating conditions, the model predicts dispersions of lithium abundance in both main sequence and pre-main sequence stages. The dispersion begins when a radiative core forms in the interior. The number sees a rapid growth afterward, reaching 0.1-0.5 dex at zero age main sequence in G and late-F stars. The increase of dispersion continues in the main sequence, which is slight in G and late-F stars while significant in mid-F stars. Finally, a comparison is carried out between the theoretical results and the observed data in four open clusters. Good agreements are obtained.

  17. Heavy metals and lead isotopes in sdB stars

    E-Print Network [OSTI]

    S. O'Toole; U. Heber

    2006-12-19

    We present a detailed abundance analysis of high-resolution ultraviolet echelle spectra of five subdwarf B stars obtained with HST-STIS The goal of our observations was to test the hypothesis that pulsations in sdBs are correlated to the surface abundances of iron-group elements. We study two pulsators and three non-pulsators and determined abundances for 25 elements including the iron group and even heavier elements such as tin and lead using LTE spectrum synthesis techniques. We find strong enrichments of heavy elements up to 2.9dex with respect to solar which are probably caused by atomic diffusion processes. No clear-cut correlation between pulsations and metal abundances becomes apparent. Abundances for lead isotopes are derived from very high resolution spectra using an UV line of triply ionised lead. As Pb terminates the s-process sequence Pb isotopic abundance ratios yield important constraints. It is very difficult to measure them in hot stars. For the first time we were able to measure them in two subluminous B stars and conclude that the 207Pb/208Pb is solar.

  18. KINEMATIC DISCOVERY OF A STELLAR STREAM LOCATED IN PISCES

    SciTech Connect (OSTI)

    Martin, Charles; Carlin, Jeffrey L.; Newberg, Heidi Jo [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Grillmair, Carl, E-mail: martic6@rpi.edu [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2013-03-10

    We report the kinematic discovery of the Pisces Stellar Stream (PSS), at Galactic longitude l Almost-Equal-To 135 Degree-Sign and -39 Degree-Sign < b < -36 Degree-Sign . We originally identified this halo substructure from velocities of red giant branch stars in the Sloan Digital Sky Survey (SDSS) Data Release 8, and confirmed its presence in turnoff stars from SDSS photometric data. The PSS is a narrow, kinematically cold tidal stream, with {sigma}{sub v,0} Almost-Equal-To 8 km s{sup -1}. Its metallicity is [Fe/H] Almost-Equal-To -2.2, with {approx}0.3 dex dispersion. The color-magnitude signature of the stream turnoff, combined with our measured metallicity, places the PSS at a distance of 35 {+-} 3 kpc. The PSS is the same as the previously announced ''Triangulum stream'' and part of the proposed ''stream a''. We rule out an association of the PSS with other previously known Milky Way substructures in the same region of the sky.

  19. Light Element Abundance Patterns in the Orion Association: I) HST Observations of Boron in G-dwarfs

    E-Print Network [OSTI]

    K. Cunha; V. Smith; E. Parizot; D. Lambert

    2000-05-22

    The boron abundances for two young solar-type members of the Orion association, BD -6 1250 and HD 294297, are derived from HST STIS spectra of the B I transition at 2496.771 A. The best-fit boron abundances for the target stars are 0.13 and 0.44 dex lower than the solar meteoritic value of log e(B)=2.78. An anticorrelation of boron and oxygen is found for Orion when these results are added to previous abundances obtained for 4 B-type stars and the G-type star BD -5 1317. An analysis of the uncertainties in the abundance calculations indicates that the observed anticorrelation is probably real. The B versus O relation observed in the Orion association does not follow the positive correlation of boron versus oxygen which is observed for the field stars with roughly solar metallicity. The observed anticorrelation can be accounted for by a simple model in which two poorly mixed components of gas (supernova ejecta and boron-enriched ambient medium) contribute to the new stars that form within the lifetime of the association. This model predicts an anticorrelation for Be as well, at least as strong as for boron.

  20. The RR Lyrae Variable Population in the Phoenix Dwarf Galaxy

    E-Print Network [OSTI]

    Ordoñez, Antonio J; Sarajedini, Ata

    2014-01-01

    We present the first detailed study of the RR Lyrae variable population in the Local Group dSph/dIrr transition galaxy, Phoenix, using previously obtained HST/WFPC2 observations of the galaxy. We utilize template light curve fitting routines to obtain best fit light curves for RR Lyrae variables in Phoenix. Our technique has identified 78 highly probable RR Lyrae stars (54 ab-type; 24 c-type) with about 40 additional candidates. We find mean periods for the two populations of $\\langle P_{ab}\\rangle = 0.60 \\pm 0.03$ days and $\\langle P_{c}\\rangle = 0.353 \\pm 0.002$ days. We use the properties of these light curves to extract, among other things, a metallicity distribution function for ab-type RR Lyrae. Our analysis yields a mean metallicity of $\\langle [Fe/H]\\rangle = -1.68 \\pm 0.06$ dex for the RRab stars. From the mean period and metallicity calculated from the ab-type RR Lyrae, we conclude that Phoenix is more likely of intermediate Oosterhoff type; however the morphology of the Bailey diagram for Phoenix R...

  1. Beryllium in the Ultra-Lithium-Deficient,Metal-Poor Halo Dwarf, G186-26

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Megan C. Novicki

    2005-09-16

    The vast majority of low-metal halo dwarfs show a similar amount of Li; this has been attributed to the Li that was produced in the Big Bang. However, there are nine known halo stars with T $>$ 5900 K and [Fe/H] $<$ $-$1.0 that are ultra-Li-deficient. We have looked for Be in the very low metallicity star, G 186-26 at [Fe/H] = $-$2.71, which is one of the ultra-Li-deficient stars. This star is also ultra-Be deficient. Relative to Be in the Li-normal stars at [Fe/H] = $-$2.7, G 182-26 is down in Be by more than 0.8 dex. Of two potential causes for the Li-deficiency -- mass-transfer in a pre-blue straggler or extra rotationally-induced mixing in a star that was initially a very rapid rotator -- the absence of Be favors the blue-straggler hypothesis, but the rotation model cannot be ruled-out completely.

  2. Analysis of RGU Photometry in Selected Area 51

    E-Print Network [OSTI]

    S. Bilir; S. Karaali; R. Buser

    2004-07-02

    A low-latitude anticenter field (l=189, b=+21) is investigated by using the full calibration tools of RGU photometry. The observed RGU data are reduced to the standard system and the separation of dwarfs and evolved stars is carried out by an empirical method. Stars are categorized into three metallicity classes, i.e. -0.25<[M/H]<=+0.50, -1.00<[M/H]<=-0.25, and [M/H]<=-1.00$ dex, and their absolute magnitudes are determined by the corresponding colour-magnitude diagrams. The unusually large scattering in the two-colour diagrams is reduced by excluding 153 extra-galactic objects, identifying them compared with the charts of Basel Astronomical Institute and University of Minnesota, and by the criterion and algorithm of Gaidos et al. (1993). The local logarithmic space density for giants, D(0)=6.75, lies within the local densities of Gliese (1969) and Gliese & Jahreiss (1992). The local luminosity function for the absolute magnitude interval 3

  3. THREE DISCRETE GROUPS WITH HOMOGENEOUS CHEMISTRY ALONG THE RED GIANT BRANCH IN THE GLOBULAR CLUSTER NGC 2808

    SciTech Connect (OSTI)

    Carretta, E., E-mail: eugenio.carretta@oabo.inaf.it [INAF, Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy)

    2014-11-10

    We present the homogeneous reanalysis of Mg and Al abundances from high resolution UVES/FLAMES spectra for 31 red giants in the globular cluster NGC 2808. We found a well defined Mg-Al anticorrelation reaching a regime of subsolar Mg abundance ratios, with a spread of about 1.4 dex in [Al/Fe]. The main result from the improved statistics of our sample is that the distribution of stars is not continuous along the anticorrelation because they are neatly clustered into three distinct clumps, each with different chemical compositions. One group (P) shows a primordial composition of field stars of similar metallicity, and the other two (I and E) have increasing abundances of Al and decreasing abundances of Mg. The fraction of stars we found in the three components (P: 68%, I: 19%, E: 13%) is in excellent agreement with the ratios computed for the three distinct main sequences in NGC 2808: for the first time there is a clear correspondence between discrete photometric sequences of dwarfs and distinct groups of giants with homogeneous chemistry. The composition of the I group cannot be reproduced by mixing of matter with extreme processing in hot H-burning and gas with pristine, unprocessed composition, as also found in the recent analysis of three discrete groups in NGC 6752. This finding suggests that different classes of polluters were probably at work in NGC 2808 as well.

  4. Lithium evolution in intermediate age and old open clusters: NGC 752 revisited

    E-Print Network [OSTI]

    P. Sestito; S. Randich; R. Pallavicini

    2004-07-15

    We present new high resolution spectroscopic observations of the intermediate age (~2 Gyr) open cluster NGC 752. We investigate the Li vs. Teff distribution and we obtain a new accurate determination of the cluster metallicity. We compare the results for NGC 752 with other intermediate age and old clusters spanning the age range from the Hyades (~0.6 Gyr) to NGC 188 (~6-8 Gyr). We find that NGC 752 has a solar iron content ([Fe/H]=+0.01+/-0.04), at variance with early reports of sub-solar metallicity. We find that NGC 752 is only slightly more Li depleted than the younger Hyades and has a Li pattern almost identical to that observed in the ~2 Gyr old IC 4651 and NGC 3680. As for the latter clusters, we find that NGC 752 is characterized by a tight Li vs. Teff distribution for solar-type stars, with no evidence for a Li spread as large as the one observed in the solar age solar metallicity M 67. We discuss these results in the framework of mixing mechanisms and Li depletion on the main sequence (MS). We conclude that the development of a large scatter in Li abundances in old open clusters might be an exception rather than the rule (additional observations of old clusters are required), and that metallicity variations of the order of ~0.2 dex do not affect Li depletion after the age of the Hyades.

  5. HST/COS detection of deuterated molecular hydrogen in a damped Ly? system at z = 0.18

    SciTech Connect (OSTI)

    Oliveira, Cristina M.; Sembach, Kenneth R.; Tumlinson, Jason; Thom, Christopher [Space Telescope Science Institute, Baltimore, MD 21218 (United States); O'Meara, John, E-mail: oliveira@stsci.edu [Saint Michael's College, Colchester, VT 05439 (United States)

    2014-03-01

    We report on the detection of deuterated molecular hydrogen, HD, at z = 0.18. HD and H{sub 2} are detected in HST/COS data of a low-metallicity (Z ? 0.07 Z {sub ?}) damped Ly? (DLA) system at z = 0.18562 toward QSO B0120–28, with log N(H I) = 20.50 ± 0.10. Four absorption components are clearly resolved in H{sub 2}, while two components are resolved in HD; the bulk of the molecular hydrogen is associated with the components traced by HD. We find total column densities log N(HD) = 14.82 ± 0.15 and log N(H{sub 2}) = 20.00 ± 0.10. This system has a high molecular fraction, f(H{sub 2}) = 0.39 ± 0.10, and a low HD-to-H{sub 2} ratio, log (HD/2H{sub 2}) = –5.5 ± 0.2 dex. The excitation temperature, T {sub 01} = 65 ± 2 K, in the component containing the bulk of the molecular gas is lower than in other DLAs. These properties are unlike those in other higher redshift DLA systems known to contain HD, but are consistent with what is observed in dense clouds in the Milky Way.

  6. A chemical trompe-l'\\oe{}il: no iron spread in the globular cluster M22

    E-Print Network [OSTI]

    Mucciarelli, A; Massari, D; Pancino, E; Stetson, P B; Ferraro, F R; Lanzoni, B; Lardo, C

    2015-01-01

    We present the analysis of high-resolution spectra obtained with UVES and UVES-FLAMES at the Very Large Telescope of 17 giants in the globular cluster M22, a stellar system suspected to have an intrinsic spread in the iron abundance. We find that when surface gravities are derived spectroscopically (by imposing to obtain the same iron abundance from FeI and FeII lines) the [Fe/H] distribution spans ~0.5 dex, according to previous analyses. However, the gravities obtained in this way correspond to unrealistic low stellar masses (0.1-0.5 Msun) for most of the surveyed giants. Instead, when photometric gravities are adopted, the [FeII/H] distribution shows no evidence of spread at variance with the [FeI/H] distribution. This difference has been recently observed in other clusters and could be due to non-local thermodynamical equilibrium effects driven by over-ionization mechanisms, that mainly affect the neutral species (thus providing lower [FeI/H]) but leave [FeII/H] unaltered. We confirm that the s-process el...

  7. Hunting the most distant stars in the Milky Way: methods and initial results

    SciTech Connect (OSTI)

    Bochanski, John J.; Willman, Beth [Haverford College, 370 Lancaster Avenue, Haverford, PA 19041 (United States); West, Andrew A. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Strader, Jay; Chomiuk, Laura, E-mail: jbochans@haverford.edu [Michigan State Astronomy Group, Michigan State University, Biomedical Physical Sciences Building, 567 Wilson Road, Room 3261, East Lansing, MI 48824-2320 (United States)

    2014-04-01

    We present a new catalog of 404 M giant candidates found in the UKIRT Infrared Deep Sky Survey (UKIDSS). The 2400 deg{sup 2} available in the UKIDSS Large Area Survey Data Release 8 resolve M giants through a volume four times larger than that of the entire Two Micron All Sky Survey. Combining near-infrared photometry with optical photometry and proper motions from the Sloan Digital Sky Survey yields an M giant candidate catalog with less M dwarf and quasar contamination than previous searches for similarly distant M giants. Extensive follow-up spectroscopy of this sample will yield the first map of our Galaxy's outermost reaches over a large area of sky. Our initial spectroscopic follow-up of ?30 bright candidates yielded the positive identification of five M giants at distances ?20-90 kpc. Each of these confirmed M giants have positions and velocities consistent with the Sagittarius stream. The fainter M giant candidates in our sample have estimated photometric distances ?200 kpc (assuming [Fe/H] = 0.0), but require further spectroscopic verification. The photometric distance estimates extend beyond the Milky Way's virial radius, and increase by ?50% for each 0.5 dex decrease in assumed [Fe/H]. Given the number of M giant candidates, initial selection efficiency, and volume surveyed, we loosely estimate that at least one additional Sagittarius-like accretion event could have contributed to the hierarchical build-up of the Milky Way's outer halo.

  8. On the oxygen abundance determination in HII regions: the problem of the line intensities -- oxygen abundance calibration

    E-Print Network [OSTI]

    L. S. Pilyugin

    2000-04-04

    The problem of the line intensities -- oxygen abundance calibration has been considered. We confirm the idea of McGaugh (1991) that the strong oxygen lines ([OII] 3727, 3729 and [OIII] 4959, 5007) contain the necessary information for determination of accurate abundances in low-metallicity (and may be also in high-metallicity) HII regions. It has been found that the excitation parameters p3 or p2 (which are defined here as contributions of the radiation in [OIII] 4959, 5007 lines and in [OII] 3727, 3729 lines to the "total" oxygen radiation respectively) allow to take into account the variations in R23 values among HII regions with a given oxygen abundance. Based on this fact a new way of the oxygen abundance determination in HII regions has been constructed and corresponding relations between line intensities and the oxygen abundance have been derived empirically using the available oxygen abundances determined via measurement of temperature-sensitive line ratios. In parallel a new R23 calibration has been derived on the base of recent data and compared to previous calibrations. For oxygen-rich HII regions the present R23 calibration is close to that of Edmunds and Pagel (1984): their calibration has the same slope but is shifted towards higher oxygen abundances by around 0.07 dex as compared to the present calibration.

  9. A New Definition for the Ca4227 Feature: Is Calcium Really Underabundant in Early-type Galaxies?

    E-Print Network [OSTI]

    L. C. Prochaska; James A. Rose; Ricardo P. Schiavon

    2005-09-26

    We have investigated the abundance of calcium in early-type galaxies by measuring the strength of the Ca I 4227 absorption line in their integrated spectra. The database used is the large sample of early-type galaxy integrated spectra in Caldwell, Rose, & Concannon (2003). We have measured Ca abundances from the Ca I 4227 feature both by using the Lick Ca4227 index and also by defining a new index, Ca4227_r, that avoids the CN4216 molecular band in the continuum on the blueward side of the line. With the new index definition we measure Ca abundances that are systematically ~0.3 dex higher than with the Lick Ca4227 index. The result is that with the new index definition we obtain higher [Ca/Fe] abundances in early-type galaxies which are more consistent with their well known [Mg/Fe] over-abundances. Hence, we suggest that Ca might be slightly enhanced, relative to Fe, in early-type galaxies.

  10. A COLD MILKY WAY STELLAR STREAM IN THE DIRECTION OF TRIANGULUM

    SciTech Connect (OSTI)

    Bonaca, Ana; Geha, Marla; Kallivayalil, Nitya, E-mail: ana.bonaca@yale.edu [Department of Astronomy, Yale University, New Haven, CT 06511 (United States)

    2012-11-20

    We present evidence for a new Milky Way stellar tidal stream in the direction of the Andromeda and Triangulum (M31 and M33) galaxies. Using a matched-filter technique, we search the Sloan Digital Sky Survey Data Release 8 by creating stellar density maps which probe the Milky Way halo at distances between 8 and 40 kpc. A visual search of these maps recovers all of the major known stellar streams, as well as a new stream in the direction of M31/M33 that we name the Triangulum stream. The stream spans 0.{sup 0}2 by 12 Degree-Sign on the sky, or 75 pc by 5.5 kpc in physical units with a best-fitting distance of 26 {+-} 4 kpc. The width of the stream is consistent with being the tidal remnant of a globular cluster. A color-magnitude diagram of the stream region shows an overdensity which, if identified as a main-sequence turnoff, corresponds to an old ({approx}12 Gyr) and metal-poor ([Fe/H] {approx}-1.0 dex) stellar population. Future kinematic studies of this and similar cold streams will provide tight constraints on the shape of the Galactic gravitational potential.

  11. Energy transport, overshoot, and mixing in the atmospheres of M-type main- and pre-main-sequence objects

    E-Print Network [OSTI]

    H. -G. Ludwig; F. Allard; P. H. Hauschildt

    2006-08-12

    We constructed hydrodynamical model atmospheres for mid M-type main-, as well as pre-main-sequence (PMS) objects. Despite the complex chemistry encountered in these cool atmospheres a reasonably accurate representation of the radiative transfer is possible, even in the context of time-dependent and three-dimensional models. The models provide detailed information about the morphology of M-type granulation and statistical properties of the convective surface flows. In particular, we determined the efficiency of the convective energy transport, and the efficiency of mixing by convective overshoot. The convective transport efficiency was expressed in terms of an equivalent mixing-length parameter alpha in the formulation of mixing-length theory (MLT) given by Mihalas (1978). Alpha amounts to values around 2 for matching the entropy of the deep, adiabatically stratified regions of the convective envelope, and lies between 2.5 and 3.0 for matching the thermal structure of the deep photosphere. For current spectral analysis of PMS objects this implies that MLT models based on alpha=2.0 overestimate the effective temperature by 100 K and surface gravities by 0.25 dex. The average thermal structure of the formally convectively stable layers is little affected by convective overshoot and wave heating, i.e., stays close to radiative equilibrium conditions. Our models suggest that the rate of mixing by convective overshoot declines exponentially with geometrical distance to the Schwarzschild stability boundary. It increases at given effective temperature with decreasing gravitational acceleration.

  12. Chemical abundances in the extremely carbon-rich and xenon-rich halo planetary nebula H4-1

    SciTech Connect (OSTI)

    Otsuka, Masaaki [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Tajitsu, Akito, E-mail: otsuka@asiaa.sinica.edu.tw, E-mail: tajitsu@subaru.naoj.org [Subaru Telescope, NAOJ, 650 North A'ohoku Place, Hilo, HI 96720 (United States)

    2013-12-01

    We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H] ? –2) halo planetary nebula (PN) H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10 elements. The C and O abundances were derived from collisionally excited lines (CELs) and are almost consistent with abundances from recombination lines (RLs). We demonstrated that the large discrepancy in the C abundance between CEL and RL in H4-1 can be solved using the temperature fluctuation model. We reported the first detection of the [Xe III] ?5846 line in H4-1 and determination of its elemental abundance ([Xe/H] > +0.48). H4-1 is the most Xe-rich PN among the Xe-detected PNe. The observed abundances are close to the theoretical prediction by a 2.0 M {sub ?} single star model with an initially element rich ([r/Fe] = +2.0 dex) rapid neutron-capture process (r-process). The observed Xe abundance would be a product of the r-process in primordial supernovae. The [C/O]-[Ba/(Eu or Xe)] diagram suggests that the progenitor of H4-1 shares the evolution with carbon-enhanced metal-poor (CEMP)-r/s and CEMP-no stars. The progenitor of H4-1 is presumably a binary formed in an r-process-rich environment.

  13. Atomic data for S II—toward better diagnostics of chemical evolution in high-redshift galaxies

    SciTech Connect (OSTI)

    Kisielius, Romas; Bogdanovich, Pavel [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Goštauto 12, LT-01108 (Lithuania); Kulkarni, Varsha P. [Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208 (United States); Ferland, Gary J.; Lykins, Matt L. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States)

    2014-01-01

    Absorption-line spectroscopy is a powerful tool used to estimate element abundances in both the nearby and distant universe. The accuracy of the abundances thus derived is naturally limited by the accuracy of the atomic data assumed for the spectral lines. We have recently started a project to perform new extensive atomic data calculations used for optical/UV spectral lines in the plasma modeling code Cloudy using state of the art quantal calculations. Here, we demonstrate our approach by focussing on S II, an ion used to estimate metallicities for Milky Way interstellar clouds as well as distant damped Lyman-alpha (DLA) and sub-DLA absorber galaxies detected in the spectra of quasars and gamma-ray bursts. We report new extensive calculations of a large number of energy levels of S II, and the line strengths of the resulting radiative transitions. Our calculations are based on the configuration interaction approach within a numerical Hartree-Fock framework, and utilize both non-relativistic and quasirelativistic one-electron radial orbitals. The results of these new atomic calculations are then incorporated into Cloudy and applied to a lab plasma, and a typical DLA, for illustrative purposes. The new results imply relatively modest changes (?0.04 dex) to the metallicities estimated from S II in past studies. These results will be readily applicable to other studies of S II in the Milky Way and other galaxies.

  14. Suppression of Star Formation in the Hosts of Low-Excitation Radio Galaxies

    E-Print Network [OSTI]

    Pace, Cameron

    2015-01-01

    The feedback from radio-loud active galactic nuclei (R-AGN) may help maintain low star formation (SF) rates in their early-type hosts, but the observational evidence for this mechanism has been inconclusive. We study systematic differences of aggregate spectral energy distributions (SEDs) of various subsets of $\\sim$4000 low-redshift R-AGN from Best & Heckman (2012) with respect to (currently) inactive control samples selected to have matching redshift, stellar mass, population age, axis ratio, and environment. Aggregate SEDs, ranging from the ultraviolet (UV) through mid-infrared (mid-IR, 22 $\\mu$m), were constructed using a Bayesian method that eliminates biases from non-detections in GALEX and WISE. We study rare high-excitation sources separately from low-excitation ones, which we split by environment and host properties. We find that both the UV and mid-IR emission of non-cluster R-AGNs (80% of sample) are suppressed by $\\sim$0.2 dex relative to that of the control group, especially for moderately ma...

  15. On the oxygen abundance determination in HII regions: High - metallicity regions

    E-Print Network [OSTI]

    L. S. Pilyugin

    2001-01-25

    This is our second paper devoted to the problem of line intensity - oxygen abundance calibration starting from the idea of McGaugh (1991) that the strong oxygen lines contain the necessary information to determine accurate abundances in HII regions. The high-metallicity HII regions are considered. A relation of the type O/H=f(P,R23) between oxygen abundance and the value of abundance index R23 introduced by Pagel et al. (1979) and the excitation parameter P (which is defined here as the contribution of the radiation in [OIII]4959,5007 lines to the "total" oxygen radiation) has been derived empirically using the available oxygen abundances determined via measurement of a temperature-sensitive line ratio [OIII]4959,5007/[OIII]4363 (Te - method). By comparing oxygen abundances derived with the Te - method and those derived with the suggested relations (P - method), it was found that the precision of oxygen abundance determination with the P - method is around 0.1 dex and is comparable to that of the Te - method. A relation of the type Te=f(P,R23) between electron temperature and the values of abundance index R23 and the excitation parameter P was derived empirically using the available electron temperatures determined via measurement of temperature-sensitive line ratios. The mean difference between electron temperatures derived through the Te=f(P,23 relation and determined via measurement of the temperature-sensitive line ratio is around 500K.

  16. s- and r-process element abundances in the CMD of 47 Tucanae using the Robert Stobie Spectrograph on SALT

    E-Print Network [OSTI]

    C. C. Worley; P. L. Cottrell; E. C. Wylie de Boer

    2008-02-04

    A recent study by Wylie et al 2006 has revealed that s-process element abundances are enhanced relative to iron in both red giant branch and asymptotic giant branch stars of 47 Tucanae. A more detailed investigation into s-process element abundances throughout the colour-magnitude diagram of 47 Tucanae is vital in order to determine whether the observed enhancements are intrinsic to the cluster. This paper explores this possibility through observational and theoretical means. The visibility of s- and r-process element lines in synthetic spectra of giant and dwarf stars throughout the colour magnitude diagram of 47 Tucanae has been explored. It was determined that a resolving power of 10 000 was sufficient to observe s-process element abundance variations in globular cluster giant branch stars. These synthetic results were compared with the spectra of eleven 47 Tucanae giant branch stars observed during the performance verification of the Robert Stobie Spectrograph on the Southern African Large Telescope. Three s-process elements, Zr, Ba, Nd, and one r-process element, Eu, were investigated. No abundance variations were found such that [X/Fe] = 0.0 +/- 0.5 dex. It was concluded that this resolving power, R ~ 5000, was not sufficient to obtain exact abundances but upper limits on the s-process element abundances could be determined.

  17. Chemical Abundances in Twelve Red Giants of the Large Magellanic Cloud from High-Resolution Infrared Spectroscopy

    E-Print Network [OSTI]

    V. V. Smith; K. H. Hinkle; K. Cunha; B. Plez; D. L. Lambert; C. A. Pilachowski; B. Barbuy; J. Melendez; S. Balachandran; M. S. Bessell; D. P. Geisler; J. E. Hesser; C. Winge

    2002-08-22

    High-resolution infrared spectra (R=50,000) have been obtained for twelve red-giant members of the LMC with the Gemini South 8.3-meter telescope plus Phoenix spectrometer. Quantitative chemical abundances of carbon-12, carbon-13, nitrogen-14, and oxygen-16 were derived from molecular lines of CO, CN, and OH, while sodium, scandium, titanium, and iron abundances were derived from neutral atomic lines. The LMC giants have masses from about 1 to 4 solar masses and span a metallicity range from [Fe/H]= -1.1 to -0.3. The program red giants all show evidence of first dredge-up mixing, with low 12C/13C ratios, and low 12C correlated with high 14N abundances. Comparisons of the oxygen-to-iron ratios in the LMC and the Galaxy indicate that the trend of [O/Fe] versus [Fe/H] in the LMC falls about 0.2 dex below the Galactic trend. Such an offset can be modeled as due to an overall lower rate of supernovae per unit mass in the LMC relative to the Galaxy, as well as a slightly lower ratio of supernovae of type II to supernovae of type Ia.

  18. Type II Cepheids in the Milky Way disc. Chemical composition of two new W Vir stars: DD Vel and HQ Car

    E-Print Network [OSTI]

    Lemasle, B; Bono, G; François, P; Saviane, I; Yegorova, I; Genovali, K; Inno, L; Galazutdinov, G; da Silva, R

    2015-01-01

    A robust classification of Cepheids into their different sub-classes and, in particular, between classical and Type II Cepheids, is necessary to properly calibrate the period-luminosity relations and for populations studies in the Galactic disc. Type II Cepheids are, however, very diverse, and classifications based either on intrinsic (period, light curve) or external parameters (e.g., [Fe/H], |z|) do not provide a unique classification. We want to ascertain the classification of two Cepheids, HQ Car and DD Vel, that are sometimes classified as classical Cepheids and sometimes as Type II Cepheids. To achieve this goal, we examine both their chemical composition and the presence of specific features in their spectra. We find emission features in the H{\\alpha} and in the 5875.64 {\\AA} He I lines that are typical of W Vir stars. The [Na/Fe] (or [Na/Zn]) abundances are typical of thick-disc stars, while BL Her stars are Na-overabundant ([Na/Fe]>+0.5 dex). Finally, the two Cepheids show a possible (HQ Car) or prob...

  19. Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars

    E-Print Network [OSTI]

    Morel, T; Aerts, C; Neiner, C; Briquet, M

    2006-01-01

    We present the results of a detailed NLTE abundance study of nine beta Cephei stars, all of them being prime targets for theoretical modelling: gamma Peg, delta Cet, nu Eri, beta CMa, xi1 CMa, V836 Cen, V2052 Oph, beta Cep and DD (12) Lac. The following chemical elements are considered: He, C, N, O, Mg, Al, Si, S and Fe. Our abundance analysis is based on a large number of time-resolved, high-resolution optical spectra covering in most cases the entire oscillation cycle of the stars. Nitrogen is found to be enhanced by up to 0.6 dex in four stars, three of which have severe constraints on their equatorial rotational velocity, \\Omega R, from seismic or line-profile variation studies: beta Cep (\\Omega R~26 km/s), V2052 Oph (\\Omega R~56 km/s), delta Cet (\\Omega R < 28 km/s) and xi1 CMa (\\Omega R sin i < 10 km/s). The existence of core-processed material at the surface of such largely unevolved, slowly-rotating objects is not predicted by current evolutionary models including rotation. We draw attention to ...

  20. The beryllium abundance in the very metal-poor halo star G 64-12 from VLT/UVES observations

    E-Print Network [OSTI]

    F. Primas; M. Asplund; P. E. Nissen; V. Hill

    2000-09-29

    We report on a new spectroscopic analysis of the very metal deficient star G 64-12 ([Fe/H]=-3.3), aimed at determining, for the first time, its Be content. The spectra were observed during the Science Verification of UVES, the ESO VLT Ultraviolet and Visible Echelle Spectrograph. The high resolution (~48,000) and high S/N (~130 per pixel) achieved at the wavelengths of the BeII resonance doublet allowed an accurate determination of its abundance: log N(Be/H) = -13.10 +/- 0.15 dex. The Be abundance is significantly higher than expected from previous measurements of Be in stars of similar metallicity (3D and NLTE corrections acting to make a slightly higher value than an LTE analysis). When compared to iron, the high [Be/Fe] ratio thus found may suggest a flattening in the beryllium evolutionary trend at the lowest metallicity end or the presence of dispersion at early epochs of galactic evolution.

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

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Megan C. Novicki

    2005-12-13

    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.

  2. Mining the Sloan digital sky survey in search of extremely ?-poor stars in the galaxy

    SciTech Connect (OSTI)

    Xing, Q. F.; Zhao, G., E-mail: qfxing@nao.cas.cn, E-mail: gzhao@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2014-07-20

    As we know, the majority of metal-poor Galactic halo stars appear to have chemical abundances that were enhanced by ?-elements (e.g., O, Mg, Si, Ca, and Ti) during the early stage of the Galaxy. Observed metal-poor halo stars preserved this pattern by exhibiting abundance ratios [?/Fe] ?+0.4. A few striking exceptions that show severe departures from the general enhanced ?-element chemical abundance trends of the halo have been discovered in recent years. They possess relatively low [?/Fe] compared to other comparable-metallicity stars, with abundance ratios over 0.5 dex lower. These stars may have a different chemical enrichment history from the majority of the halo. Similarly, low-? abundances are also displayed by satellite dwarf spheroidal (dSph) galaxies. We present a method to select extremely ?-poor (EAP) stars from the SDSS/SEGUE survey. The method consists of a two-step approach. In the first step, we select suspected metal-poor ([Fe/H] <–0.5) and ?-poor ([Mg/Fe] <0) stars as our targets. In the second step, we determine [Mg/Fe] from low-resolution (R = 2000) stellar spectra for our targets and select stars with [Mg/Fe] <–0.1 as candidate EAP stars. In a sample of 40,000 stars with atmospheric parameters in the range of T{sub eff} = [4500, 7000] K, log g = [1.0, 5.0], and [Fe/H] = [–4.0, +0.5], 14 candidate stars were identified. Three of these stars are found to have already been confirmed by other research.

  3. Beryllium abundance in turn-off stars of NGC 6752

    E-Print Network [OSTI]

    Luca Pasquini; Piercarlo Bonifacio; Sofia Randich; Daniele Galli; Raffaele G. Gratton; B. Wolff

    2006-12-27

    Aims: To measure the beryllium abundance in two TO stars of the Globular Cluster NGC 6752, one oxygen rich and sodium poor, the other presumably oxygen poor and sodium rich. Be abundances in these stars are used to put on firmer grounds the hypothesis of Be as cosmochronometer and to investigate the formation of Globular Clusters. Method:We present near UV spectra with resolution R$\\sim 45000$ obtained with the UVES spectrograph on the 8.2m VLT Kueyen telescope, analysed with spectrum synthesis based on plane parallel LTE model atmospheres. Results:Be is detected in the O rich star with log(Be/H)=-12.04 $\\pm$0.15, while Be is not detected in the other star for which we obtain the upper limit log(Be/H)$<$-12.2. A large difference in nitrogen abundance (1.6 dex) is found between the two stars. Conclusions:The Be measurement is compatible with what found in field stars with the same [Fe/H] and [O/H]. The 'Be age' of the cluster is found to be 13.3 Gyrs, in excellent agreement with the results from main sequence fitting and stellar evolution. The presence of Be confirms the results previously obtained for the cluster NGC 6397 and supports the hypothesis that Be can be used as a clock for the early formation of the Galaxy. Since only an upper limit is found for the star with low oxygen abundance, we cannot decide between competing scenarios of Globular Cluster formation, but we can exclude that 'polluted' stars are substantially younger than 'unpolluted' ones. We stress that the Be test might be the only measurement capable of distinguishing between these scenarios.

  4. New beryllium observations in low-metallicity stars

    E-Print Network [OSTI]

    P. Molaro; P. Bonifacio; F. Castelli; L. Pasquini

    1996-08-03

    We present observations of the Be II 313.0 nm resonance doublet in 14 halo and old disk stars with metallicities ranging from [Fe/H]=-0.4 to about -3.0 obtained with the CASPEC spectrograph of the ESO 3.6m telescope at a FWHM about 8.6 km/s resolution. Abundances are derived by means of the synthetic spectra technique employing Kurucz (1993) atmospheric models, with enhanced alpha-elements and no overshooting. The derived abundances together with those available in literature show that for -2.7 < [Fe/H] < -0.8 Be correlates linearly with iron [Be] proportional to 1.07(+/- 0.08)[Fe/H], giving strength to previous results. However, a steeper correlation is still possible at metallicities lower than [Fe/H]<-1.4 with [Be] proportional to 1.6(+/- 0.44)[Fe/H]. When iron is replaced with oxygen, Be is found tracking closely oxygen up to solar values, without signs of breaking in correspondence of the onset of the Galactic disk. No evidence of intrinsic dispersion is found, ought to the large errors involved in the Be abundance determinations, but for three stars (HD 106516, HD 3795, HD 211998) a significant upper limit in the Be abundance can be placed at about 1 dex below the mean trend of the Be-Fe relation. For such stars non conventional mixing is required to explain Be depletion. Be observations can be used to discriminate strongly Li-depleted stars. These are the stars which show less Li than that expected by high energy cosmic rays production as deduced from Be observations. The available Be observations imply that some of the stars which contribute to the scatter in the Li-Fe diagramme are Li-depleted stars.

  5. Chemical Evolution of Odd Elements in an Inhomogeneous Early Galaxy

    E-Print Network [OSTI]

    Takuji Tsujimoto; Toshikazu Shigeyama; Yuzuru Yoshii

    2001-09-20

    We investigate the chemical evolution of odd-numbered elements such as sodium (Na) and aluminum (Al) during the early epochs of the Galactic halo with the use of a model that reproduces the observed box-shaped distribution of extremely metal-poor stars in the [Na, Al/Mg] versus [Mg/H] plane. Our model is constructed under the assumptions that those stars retain the elemental abundance patterns produced by individual Type II supernovae (SNe), and that the yields of the odd elements depend on the initial metallicity, z, of their SN progenitors. As a result, recent abundance determinations that clarify how the [Na, Al/Mg] ratios of field stars have evolved to the solar values enable us to deduce how the yields of these odd elements depend on z. The observed trends in these abundances, in particular the very large scatter (over 1 dex in [Al/Mg]) requires that the Al yield scales as m_Al proportional to z^0.6 for [Mg/H]-1.8. It is found that the predicted frequency distribution of stars in the [Na/Mg] versus [Mg/H] diagram is very sensitive to the assumed form of the primordial IMF, and that its slope is steeper than the Salpeter IMF. The necessity to match the observed abundance patterns of odd elements and the frequency distribution of extremely metal-poor stars should provide useful constraints on nucleosynthesis calculations of metal-free massive stars as well as on theories of their formation.

  6. THE ZURICH ENVIRONMENTAL STUDY (ZENS) OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. V. PROPERTIES AND FREQUENCY OF MERGING SATELLITES AND CENTRALS IN DIFFERENT ENVIRONMENTS

    SciTech Connect (OSTI)

    Pipino, A.; Cibinel, A.; Tacchella, S.; Carollo, C. M.; Lilly, S. J.; Miniati, F. [Institute for Astronomy, ETH Zurich, Wolfgang-PauiI-Strasse 27, 8093 Zurich (Switzerland); Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8583 (Japan); Van Gorkom, J. H. [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Finoguenov, A., E-mail: anna.cibinel@cea.fr [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland)

    2014-12-20

    We use the Zurich Environmental Study database to investigate the environmental dependence of the merger fraction ? and merging galaxy properties in a sample of ?1300 group galaxies with M > 10{sup 9.2} M {sub ?} and 0.05 < z < 0.0585. In all galaxy mass bins investigated in our study, we find that ? decreases by a factor of ?2-3 in groups with halo masses M {sub HALO} > 10{sup 13.5} M {sub ?} relative to less massive systems, indicating a suppression of merger activity in large potential wells. In the fiducial case of relaxed groups only, we measure a variation of ??/?log (M {sub HALO}) ? –0.07 dex{sup –1}, which is almost independent of galaxy mass and merger stage. At galaxy masses >10{sup 10.2} M {sub ?}, most mergers are dry accretions of quenched satellites onto quenched centrals, leading to a strong increase of ? with decreasing group-centric distance at these mass scales. Both satellite and central galaxies in these high-mass mergers do not differ in color and structural properties from a control sample of nonmerging galaxies of equal mass and rank. At galaxy masses of <10{sup 10.2} M {sub ?} where we mostly probe satellite-satellite pairs and mergers between star-forming systems close pairs (projected distance <10-20 kpc) show instead ?2 × enhanced (specific) star formation rates and ?1.5 × larger sizes than similar mass, nonmerging satellites. The increase in both size and star formation rate leads to similar surface star formation densities in the merging and control-sample satellite populations.

  7. Beryllium in the Hyades F and G Dwarfs from Keck/HIRES Spectra

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Jeremy R. King

    2001-09-18

    Beryllium is not destroyed as easily as Li, so the abundances of Li and Be together can tell us more about the internal physical processes in stars than either element can alone. We have obtained high-resolution (45,000) and high signal-to-noise (typically 90 per pixel) spectra of the Be II resonance lines in 34 Hyades F and G dwarfs with the Keck I telescope and HIRES. The Be abundances have been derived with the spectrum synthesis method. We find that Be is depleted in the Li gap in the F stars reaching down to values of A(Be) = 0.60, or a factor of nearly seven below the meteoritic Be abundance. There is little or no depletion of Be in stars cooler than 6000 K, in spite of the large depletions (0.5 - 2.5 dex) in Li. The mean value of A(Be) for the ten coolest stars is 1.33 +/- 0.06, not far from the meteoritic value of 1.42. The pattern in the Be abundances - a Be dip in the F stars and undepleted Be in the cool stars - is well matched by the predictions of slow mixing due to stellar rotation (e.g. Deliyannis and Pinsonneault). The depletions of Li and Be probably occur simultaneously. The Li and Be abundances are correlated for stars in the temperature range of 5850 - 6680 K, similar to results from earlier work on Li and Be in F and G field stars. The Hyades G dwarfs have more Be than the sun; their initial Be may have been larger or they may not be old enough to have depleted Be. For those Hyades stars which appear to have little or no depletion of Li or Be, the Li/Be ratio is found to be 75 +/- 30. (abridged)

  8. Stochastic chemical enrichment in metal-poor systems II. Abundance ratios and scatter

    E-Print Network [OSTI]

    T. Karlsson; B. Gustafsson

    2005-04-27

    A stochastic model of the chemical enrichment of metal-poor systems by core-collapse supernovae is used to study the scatter in stellar abundance ratios. The resulting scatter in abundance ratios, e.g. as functions of the overall metallicity, is demonstrated to be crucially dependent on the as yet uncertain supernovae yields. The observed abundance ratios and their scatters therefore have diagnostic power as regards the yields. The relatively small star-to-star scatter observed in many chemical abundance ratios, e.g. by Cayrel et al. (2004) for stars down to [Fe/H] = -4, is tentatively explained by the averaging of a large number of contributing supernovae and by the cosmic selection effects favoring contributions from supernovae in a certain mass range for the most metal-poor stars. The scatter in observed abundances of alpha-elements is understood in terms of observational errors only, while additional spread in yields or sites of nucleosynthesis may affect the odd-even elements Na and Al. For the iron-group elements we find systematically too high predicted Cr/Fe and Cr/Mg ratios, as well as differences between the different sets of yields, both in terms of predicted abundance ratios and scatter. The semi-empirical yields recently suggested by Francois et al. (2004) are found to lead to scatter in abundance ratios significantly greater than observed, when applied in the inhomogeneous models. "Spurs", very narrow sequences in abundance-ratio diagrams, may disclose a single-supernova origin of the elements of the stars on the sequence. Verification of the existence of such features, called single supernova sequences (SSSs), is challenging. This will require samples of several hundred stars with abundance ratios observed to accuracies of 0.05 dex or better.

  9. The RR Lyrae variable population in the Phoenix dwarf galaxy

    SciTech Connect (OSTI)

    Ordoñez, Antonio J.; Sarajedini, Ata [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Yang, Soung-Chul, E-mail: a.ordonez@ufl.edu, E-mail: ata@astro.ufl.edu, E-mail: sczoo@kasi.re.kr [Korea Astronomy and Space Science Institute (KASI), Daejeon 305-348 (Korea, Republic of)

    2014-05-10

    We present the first detailed study of the RR Lyrae variable population in the Local Group dSph/dIrr transition galaxy, Phoenix, using previously obtained HST/WFPC2 observations of the galaxy. We utilize template light curve fitting routines to obtain best fit light curves for RR Lyrae variables in Phoenix. Our technique has identified 78 highly probable RR Lyrae stars (54 ab-type; 24 c-type) with about 40 additional candidates. We find mean periods for the two populations of (P {sub ab}) = 0.60 ± 0.03 days and (P{sub c} ) = 0.353 ± 0.002 days. We use the properties of these light curves to extract, among other things, a metallicity distribution function for ab-type RR Lyrae. Our analysis yields a mean metallicity of ([Fe/H]) = –1.68 ± 0.06 dex for the RRab stars. From the mean period and metallicity calculated from the ab-type RR Lyrae, we conclude that Phoenix is more likely of intermediate Oosterhoff type; however the morphology of the Bailey diagram for Phoenix RR Lyraes appears similar to that of an Oosterhoff type I system. Using the RRab stars, we also study the chemical enrichment law for Phoenix. We find that our metallicity distribution is reasonably well fitted by a closed-box model. The parameters of this model are compatible with the findings of Hidalgo et al., further supporting the idea that Phoenix appears to have been chemically enriched as a closed-box-like system during the early stage of its formation and evolution.

  10. Submission : 13593 Thesis proposal CSC 2015

    E-Print Network [OSTI]

    Bordenave, Charles

    and Dmitry Valyaev E-mail address: noel.lugan@lcc-toulouse.fr PhD School name: Physics, Chemistry & Material as anti-knocking gasoline additive. [4] Valyaev, D. A.; Bastin, S.; Utegenov, K. I.; Lugan, N.; Lavigne, G.; Ustynyuk, N. A. Chem. Eur. J. 2014, 20, 2175. [5] Valyaev, D. A.; Filippov, O. A.; Lugan, N.; Lavigne, G

  11. THE CONNECTION BETWEEN GALAXIES AND DARK MATTER STRUCTURES IN THE LOCAL UNIVERSE

    SciTech Connect (OSTI)

    Reddick, Rachel M.; Wechsler, Risa H.; Behroozi, Peter S.; Tinker, Jeremy L. E-mail: rwechsler@stanford.edu

    2013-07-01

    We provide new constraints on the connection between galaxies in the local universe, identified by the Sloan Digital Sky Survey, and dark matter halos and their constituent substructures in the {Lambda}-cold dark matter model using WMAP7 cosmological parameters. Predictions for the abundance and clustering properties of dark matter halos, and the relationship between dark matter hosts and substructures, are based on a high-resolution cosmological simulation, the Bolshoi simulation. We associate galaxies with dark matter halos and subhalos using subhalo abundance matching, and perform a comprehensive analysis which investigates the underlying assumptions of this technique including (1) which halo property is most closely associated with galaxy stellar masses and luminosities, (2) how much scatter is in this relationship, and (3) how much subhalos can be stripped before their galaxies are destroyed. The models are jointly constrained by new measurements of the projected two-point galaxy clustering and the observed conditional stellar mass function of galaxies in groups. We find that an abundance matching model that associates galaxies with the peak circular velocity of their halos is in good agreement with the data, when scatter of 0.20 {+-} 0.03 dex in stellar mass at a given peak velocity is included. This confirms the theoretical expectation that the stellar mass of galaxies is tightly correlated with the potential wells of their dark matter halos before they are impacted by larger structures. The data put tight constraints on the satellite fraction of galaxies as a function of galaxy stellar mass and on the scatter between halo and galaxy properties, and rule out several alternative abundance matching models that have been considered. This will yield important constraints for galaxy formation models, and also provides encouraging indications that the galaxy-halo connection can be modeled with sufficient fidelity for future precision studies of the dark universe.

  12. The Connection between Galaxies and Dark Matter Structures in the Local Universe

    SciTech Connect (OSTI)

    Reddick, Rachel M.; Wechsler, Risa H.; Tinker, Jeremy L.; Behroozi, Peter S.

    2012-07-11

    We provide new constraints on the connection between galaxies in the local Universe, identified by the Sloan Digital Sky Survey (SDSS), and dark matter halos and their constituent substructures in the {Lambda}CDM model using WMAP7 cosmological parameters. Predictions for the abundance and clustering properties of dark matter halos, and the relationship between dark matter hosts and substructures, are based on a high-resolution cosmological simulation, the Bolshoi simulation. We associate galaxies with dark matter halos and subhalos using subhalo abundance matching, and perform a comprehensive analysis which investigates the underlying assumptions of this technique including (a) which halo property is most closely associated with galaxy stellar masses and luminosities, (b) how much scatter is in this relationship, and (c) how much subhalos can be stripped before their galaxies are destroyed. The models are jointly constrained by new measurements of the projected two-point galaxy clustering and the observed conditional stellar mass function of galaxies in groups. We find that an abundance matching model that associates galaxies with the peak circular velocity of their halos is in good agreement with the data, when scatter of 0.20 {+-} 0.03 dex in stellar mass at a given peak velocity is included. This confirms the theoretical expectation that the stellar mass of galaxies is tightly correlated with the potential wells of their dark matter halos before they are impacted by larger structures. The data put tight constraints on the satellite fraction of galaxies as a function of galaxy stellar mass and on the scatter between halo and galaxy properties, and rule out several alternative abundance matching models that have been considered. This will yield important constraints for galaxy formation models, and also provides encouraging indications that the galaxy - halo connection can be modeled with sufficient fidelity for future precision studies of the dark Universe.

  13. The trace of the CNO cycle in the ring nebula NGC 6888

    SciTech Connect (OSTI)

    Mesa-Delgado, A.; Esteban, C.; García-Rojas, J.; Reyes-Pérez, J.; Morisset, C.; Bresolin, F.

    2014-04-20

    We present new results on the chemical composition of the Galactic ring nebula NGC 6888 surrounding the WN6(h) star WR136. The data are based on deep spectroscopical observations taken with the High Dispersion Spectrograph at the 8.2 m Subaru Telescope. The spectra cover the optical range from 3700 to 7400 Å. The effect of the CNO cycle is well-identified in the abundances of He, N, and O, while elements not involved in the synthesis such as Ar, S, and Fe present values consistent with the solar vicinity and the ambient gas. The major achievement of this work is the first detection of the faint C II ?4267 recombination line in a Wolf-Rayet nebula. This allows us to estimate the C abundance in NGC 6888 and therefore investigate for the first time the trace of the CNO cycle in a ring nebula around a Wolf-Rayet star. Although the detection of the C II line has a low signal-to-noise ratio, the C abundance seems to be higher than the predictions of recent stellar evolution models of massive stars. The Ne abundance also shows a puzzling pattern with an abundance of about 0.5 dex lower than the solar vicinity, which may be related to the action of the NeNa cycle. Attending to the constraints imposed by the dynamical timescale and the He/H and N/O ratios of the nebula, the comparison with stellar evolution models indicates that the initial mass of the stellar progenitor of NGC 6888 is between 25 M {sub ?} and 40 M {sub ?}.

  14. High precision density measurements in the solar corona: I. Analysis methods and results for Fe XII and Fe XIII

    E-Print Network [OSTI]

    P. R. Young; T. Watanabe; H. Hara; J. T. Mariska

    2008-10-28

    The EUV Imaging Spectrometer (EIS) instrument on board the Hinode satellite has access to some of the best coronal density diagnostics and the high sensitivity of the instrument now allows electron number density, N_e, measurements to an unprecedented precision of up to +/-5 % in active regions. This paper gives a thorough overview of data analysis issues for the best diagnostics of Fe XII and Fe XIII and assesses the accuracy of the measurements. Two density diagnostics each from Fe XII (186.88/195.12 and 196.64/195.12) and Fe XIII (196.54/202.04 and 203.82/202.04) are analysed in two active region data-sets from 2007 May 3 and 6 that yield densities in the range 8.5 < log N_e < 11.0. The densities are derived using v5.2 of the CHIANTI atomic database. The Fe XII and Fe XIII diagnostics show broadly the same trend in density across the active region, consistent with their similar temperatures of formation. However the high precision of the EIS measurements demonstrates significant discrepancies of up to 0.5 dex in derived log N_e values, with Fe XII always giving higher densities than Fe XIII. The discrepancies may partly be due to real physical differences between the emitting regions of the two plasmas, but the dominant factor lies in the atomic models of the two ions. Two specific problems are identified for Fe XII 196.64 and Fe XIII 203.82: the former is found to be under-estimated in strength by the CHIANTI atomic model, while the high density limit of the 203.82/202.04 is suggested to be inaccurate in the CHIANTI atomic model. The small grating tilt of the EIS instrument is found to be very significant when deriving densities from emission lines separated by more than a few angstroms.

  15. Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars

    E-Print Network [OSTI]

    T. Morel; K. Butler; C. Aerts; C. Neiner; M. Briquet

    2006-07-12

    We present the results of a detailed NLTE abundance study of nine beta Cephei stars, all of them being prime targets for theoretical modelling: gamma Peg, delta Cet, nu Eri, beta CMa, xi1 CMa, V836 Cen, V2052 Oph, beta Cep and DD (12) Lac. The following chemical elements are considered: He, C, N, O, Mg, Al, Si, S and Fe. Our abundance analysis is based on a large number of time-resolved, high-resolution optical spectra covering in most cases the entire oscillation cycle of the stars. Nitrogen is found to be enhanced by up to 0.6 dex in four stars, three of which have severe constraints on their equatorial rotational velocity, \\Omega R, from seismic or line-profile variation studies: beta Cep (\\Omega R~26 km/s), V2052 Oph (\\Omega R~56 km/s), delta Cet (\\Omega R < 28 km/s) and xi1 CMa (\\Omega R sin i < 10 km/s). The existence of core-processed material at the surface of such largely unevolved, slowly-rotating objects is not predicted by current evolutionary models including rotation. We draw attention to the fact that three stars in this subsample have a detected magnetic field and briefly discuss recent theoretical work pointing to the occurrence of diffusion effects in beta Cephei stars possibly capable of altering the nitrogen surface abundance. On the other hand, the abundances of all the other chemical elements considered are, within the errors, indistinguishable from the values found for OB dwarfs in the solar neighbourhood. Despite the mild nitrogen excess observed in some objects, we thus find no evidence for a significantly higher photospheric metal content in the studied beta Cephei stars compared to non-pulsating B-type stars of similar characteristics.

  16. Prospecting in ultracool dwarfs: measuring the metallicities of mid- and late-M dwarfs

    SciTech Connect (OSTI)

    Mann, Andrew W. [Department of Astronomy, University of Texas at Austin, TX (United States); Deacon, Niall R. [Max Planck Institute for Astronomy, Konigstuhl 17, Heidelberg D-69117 (Germany); Gaidos, Eric [Department of Geology and Geophysics, University of Hawai'i, 1680 East-West Road, Honolulu, HI 96822 (United States); Ansdell, Megan; Liu, Michael C.; Magnier, Eugene A.; Aller, Kimberly M. [Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Brewer, John M. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States)

    2014-06-01

    Metallicity is a fundamental parameter that contributes to the physical characteristics of a star. The low temperatures and complex molecules present in M dwarf atmospheres make it difficult to measure their metallicities using techniques that have been commonly used for Sun-like stars. Although there has been significant progress in developing empirical methods to measure M dwarf metallicities over the last few years, these techniques have been developed primarily for early- to mid-M dwarfs. We present a method to measure the metallicity of mid- to late-M dwarfs from moderate resolution (R ? 2000) K-band (? 2.2 ?m) spectra. We calibrate our formula using 44 wide binaries containing an F, G, K, or early-M primary of known metallicity and a mid- to late-M dwarf companion. We show that similar features and techniques used for early-M dwarfs are still effective for late-M dwarfs. Our revised calibration is accurate to ?0.07 dex for M4.5-M9.5 dwarfs with –0.58 < [Fe/H] < +0.56 and shows no systematic trends with spectral type, metallicity, or the method used to determine the primary star metallicity. We show that our method gives consistent metallicities for the components of M+M wide binaries. We verify that our new formula works for unresolved binaries by combining spectra of single stars. Lastly, we show that our calibration gives consistent metallicities with the Mann et al. study for overlapping (M4-M5) stars, establishing that the two calibrations can be used in combination to determine metallicities across the entire M dwarf sequence.

  17. The iron abundance of the Magellanic Bridge

    E-Print Network [OSTI]

    P. L. Dufton; R. S. I. Ryans; H. M. A. Thompson; R. A. Street

    2008-02-01

    High-resolution HST ultra-violet spectra for five B-type stars in the Magellanic Bridge and in the Large and Small Magellanic Clouds have been analysed to estimate their iron abundances. Those for the Clouds are lower than estimates obtained from late-type stars or the optical lines in B-type stars by approximately 0.5 dex. This may be due to systematic errors possibly arising from non-LTE effects or from errors in the atomic data as similar low Fe abundances having previously been reported from the analysis of the ultra-violet spectra of Galactic early-type stars. The iron abundance estimates for all three Bridge targets appear to be significantly lower than those found for the SMC and LMC by approximately -0.5 dex and -0.8 dex respectively and these differential results should not be affected by any systematic errors present in the absolute abundance estimates. These differential iron abundance estimates are consistent with the underabundances for C, N, O, Mg and Si of approximately -1.1 dex relative to our Galaxy previously found in our Bridge targets. The implications of these very low metal abundances for the Magellanic Bridge are discussed in terms of metal deficient material being stripped from the SMC.

  18. SIAM REVIEW c 1999 Society for Industrial and Applied Mathematics Vol. 41, No. 2, pp. 335362

    E-Print Network [OSTI]

    Tino, Peter

    Abstract. The evolution of digital libraries and the Internet has dramatically transformed the pro- cessing materials on a particular topic, procedures for in- dexing or extracting the knowledge or conceptual, singular value decomposition, vector spaces AMS subject classifications. 15-01, 15A03, 15A18, 65F50, 68P20

  19. EVIDENCE THAT GAMMA-RAY BURST 130702A EXPLODED IN A DWARF SATELLITE OF A MASSIVE GALAXY

    SciTech Connect (OSTI)

    Kelly, Patrick L.; Filippenko, Alexei V.; Fox, Ori D.; Zheng Weikang; Clubb, Kelsey I., E-mail: pkelly@astro.berkeley.edu [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

    2013-09-20

    GRB 130702A is a nearby long-duration gamma-ray burst (LGRB) discovered by the Fermi satellite whose associated afterglow was detected by the Palomar Transient Factory. Subsequent photometric and spectroscopic monitoring has identified a coincident broad-lined Type Ic supernova (SN), and nebular emission detected near the explosion site is consistent with a redshift of z = 0.145. The SN-GRB exploded at an offset of {approx}7.''6 from the center of an inclined r = 18.1 mag red disk-dominated galaxy, and {approx}0.''6 from the center of a much fainter r = 23 mag object. We obtained Keck-II DEIMOS spectra of the two objects and find a 2{sigma} upper limit on their line-of-sight velocity offset of {approx}<60 km s{sup -1}. If we calculate the inclination angle of the massive red galaxy from its axis ratio and assume that its light is dominated by a very thin disk, the explosion would have a {approx}60 kpc central offset, or {approx}9 times the galaxy's half-light radius. A significant bulge or a thicker disk would imply a higher inclination angle and greater central offset. The substantial offset suggests that the faint source is a separate dwarf galaxy. The star-formation rate of the dwarf galaxy is {approx}0.05 M{sub Sun} yr{sup -1}, and we place an upper limit on its oxygen abundance of 12 + log(O/H) < 8.16 dex. The identification of an LGRB in a dwarf satellite of a massive, metal-rich primary galaxy suggests that recent detections of LGRBs spatially coincident with metal-rich galaxies may be, in some cases, superpositions.

  20. CHEMICAL ABUNDANCES IN FIELD RED GIANTS FROM HIGH-RESOLUTION H-BAND SPECTRA USING THE APOGEE SPECTRAL LINELIST

    SciTech Connect (OSTI)

    Smith, Verne V.; Cunha, Katia [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States)] [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States); Shetrone, Matthew D. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States)] [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Meszaros, Szabolcs; Allende Prieto, Carlos [Instituto d'Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain)] [Instituto d'Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain); Bizyaev, Dmitry [Apache Point Observatory, Sunspot, NM 88349 (United States)] [Apache Point Observatory, Sunspot, NM 88349 (United States); Garcia Perez, Ana; Majewski, Steven R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)] [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Schiavon, Ricardo [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5UX (United Kingdom)] [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5UX (United Kingdom); Holtzman, Jon [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)] [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Johnson, Jennifer A., E-mail: vsmith@noao.edu [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States)

    2013-03-01

    High-resolution H-band spectra of five bright field K, M, and MS giants, obtained from the archives of the Kitt Peak National Observatory Fourier transform spectrometer, are analyzed to determine chemical abundances of 16 elements. The abundances were derived via spectrum synthesis using the detailed linelist prepared for the Sloan Digital Sky Survey III Apache Point Galactic Evolution Experiment (APOGEE), which is a high-resolution near-infrared spectroscopic survey to derive detailed chemical abundance distributions and precise radial velocities for 100,000 red giants sampling all Galactic stellar populations. The red giant sample studied here was chosen to probe which chemical elements can be derived reliably from the H-band APOGEE spectral region. These red giants consist of two K-giants ({alpha} Boo and {mu} Leo), two M-giants ({beta} And and {delta} Oph), and one thermally pulsing asymptotic giant branch (TP-AGB) star of spectral type MS (HD 199799). Measured chemical abundances include the cosmochemically important isotopes {sup 12}C, {sup 13}C, {sup 14}N, and {sup 16}O, along with Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The K and M giants exhibit the abundance signature of the first dredge-up of CN-cycle material, while the TP-AGB star shows clear evidence of the addition of {sup 12}C synthesized during {sup 4}He-burning thermal pulses and subsequent third dredge-up. A comparison of the abundances derived here with published values for these stars reveals consistent results to {approx}0.1 dex. The APOGEE spectral region and linelist is thus well suited for probing both Galactic chemical evolution, as well as internal nucleosynthesis and mixing in populations of red giants via high-resolution spectroscopy.

  1. THE LICK/SDSS LIBRARY. II. [Ca/Fe] AND [Mg/Fe] IN F, G, AND K STARS FROM SDSS-DR7

    SciTech Connect (OSTI)

    Franchini, M.; Morossi, C.; Di Marcantonio, P.; Malagnini, M. L. [INAF-Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste (Italy); Chavez, M., E-mail: franchini@oats.inaf.it, E-mail: morossi@oats.inaf.it, E-mail: dimarcan@oats.inaf.it, E-mail: malagnini@oats.inaf.it, E-mail: mchavez@inaoep.mx [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro 1, 72840 Tonantzintla, Puebla (Mexico)

    2011-04-01

    We analyzed the spectra of 17,600 F, G, and K stars extracted from the seventh Sloan Digital Sky Survey Data Release (SDSS-DR7) database in order to derive ([{alpha}/Fe]), [Ca/Fe], and [Mg/Fe] ratios. Particular attention has been devoted to estimating homogeneous and self-consistent atmospheric parameter values, T{sub eff}, log g, and [Fe/H], by comparing synthetic and observational Lick/SDSS indices. We present results for the sub-sample of more than 4000 spectra whose overall quality allowed us to derive fairly accurate stellar atmospheric parameter values and, therefore, reliable abundance ratios. A Monte Carlo approach was adopted to evaluate both the errors in the observational Lick/SDSS indices and in the derived parameter estimates. The analysis of the trends of [Ca/Fe] and [Mg/Fe] versus [Fe/H] pointed out that (1) the [Ca/Fe] and [Mg/Fe] ratios increase with decreasing [Fe/H] with different slopes reaching maximum average levels of +0.25 and +0.40 dex at [Fe/H] {approx_equal} -1.75, respectively; (2) our sample contains, at a given [Fe/H], stars characterized by significantly different amounts of {alpha}-enhancement, thus belonging to different Galactic populations; and (3) the analyzed sample shows a predominance of thick disk stars for [Fe/H] > - 0.5 and the presence of stars belonging to the 'high-{alpha}' halo population for -2.0 < [Fe/H] <-0.5.

  2. Production of Lithium in the Galactic Disk

    E-Print Network [OSTI]

    E; Casuso; J. E. Beckman

    2000-05-03

    We examine the evolution of Li in the Galactic disk,basing our model on the compilation of Li v.Fe observations in stars of iron abundance ranging between halo values,which give a baseline for the disk Li abundance,and 0.2 dex above solar.The upper envelope of these observations is taken to represent the locus of minimum stellar Li depletion,and thus to follow the Galactic IS Li abundance.The most striking feature of this envelope is its steep rise between Fe/H ~ -0.4 and -0.2,corresponding to a relatively late epoch.The Li abundance increases by an order of magnitude,from its halo value of logLi ~2.2 to the "current" value of ~3.2 within this narrow range of Fe abundances.It is well known that spallation reactions between CNO and 4He in the ISM produce Li,but models give a nearly tenfold shortfall for this process.The alpha+alpha fusion reaction appeared to yield too much early Li or too little current Li.These failures led to the exploration of stellar sources:supernovae,novae,and the He flash phase in AGB stars.The Li-Fe envelope is a strong constraint on any process.Our models can account for this in the context of disk chemical evolution with a near constant or growing rate of low metallicity gas infall,and a purely interstellar Li source: alpha-alpha fusion.The Li production rate is found to be proportional to the gas expulsion rate from intermediate and low mass stars.Low-energy alphas,emitted by these stars,but accelerated in more energetic processes associated with SNe,or the bow-shocks of stellar winds,can yield the observed abundance and its variation with Fe or O.Our model is consistent with the cosmic ray spectrum in the few MeV range,corrected for solar modulation and with new 7Li/6Li ratios found by Knauth et al.(2000) in the local ISM.

  3. TYPE Ia SUPERNOVA REMNANT SHELL AT z = 3.5 SEEN IN THE THREE SIGHTLINES TOWARD THE GRAVITATIONALLY LENSED QSO B1422+231

    SciTech Connect (OSTI)

    Hamano, Satoshi; Kobayashi, Naoto [Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Kondo, Sohei [Koyama Astronomical Observatory, Kyoto-Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555 (Japan); Tsujimoto, Takuji [National Astronomical Observatory of Japan and Department of Astronomical Science, Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Okoshi, Katsuya [Faculty of Industrial Science and Technology, Tokyo University of Science, 102-1 Tomino, Oshamanbe, Hokkaido 049-3514 (Japan); Shigeyama, Toshikazu, E-mail: hamano@ioa.s.u-tokyo.ac.jp [Research Center for the Early Universe, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan)

    2012-08-01

    Using the Subaru 8.2 m Telescope with the IRCS Echelle spectrograph, we obtained high-resolution (R = 10,000) near-infrared (1.01-1.38 {mu}m) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z = 3.628) consisting of four known lensed images. We detected Mg II absorption lines at z = 3.54, which show a large variance of column densities ({approx}0.3 dex) and velocities ({approx}10 km s{sup -1}) between sightlines A and B with a projected separation of only 8.4h{sup -1}{sub 70} pc at that redshift. This is the smallest spatial structure of the high-z gas clouds ever detected after Rauch et al. found a 20 pc scale structure for the same z = 3.54 absorption system using optical spectra of images A and C. The observed systematic variances imply that the system is an expanding shell as originally suggested by Rauch et al. By combining the data for three sightlines, we managed to constrain the radius and expansion velocity of the shell ({approx}50-100 pc, 130 km s{sup -1}), concluding that the shell is truly a supernova remnant (SNR) rather than other types of shell objects, such as a giant H II region. We also detected strong Fe II absorption lines for this system, but with much broader Doppler width than that of {alpha}-element lines. We suggest that this Fe II absorption line originates in a localized Fe II-rich gas cloud that is not completely mixed with plowed ambient interstellar gas clouds showing other {alpha}-element low-ion absorption lines. Along with the Fe richness, we conclude that the SNR is produced by an SN Ia explosion.

  4. SDSS/SEGUE spectral feature analysis for stellar atmospheric parameter estimation

    SciTech Connect (OSTI)

    Li, Xiangru; Lu, Yu; Yang, Tan; Wang, Yongjun; Wu, Q. M. Jonathan; Luo, Ali; Zhao, Yongheng; Zuo, Fang

    2014-08-01

    Large-scale and deep sky survey missions are rapidly collecting a large amount of stellar spectra, which necessitate the estimation of atmospheric parameters directly from spectra and make it feasible to statistically investigate latent principles in a large data set. We present a technique for estimating parameters T{sub eff}, log g, and [Fe/H] from stellar spectra. With this technique, we first extract features from stellar spectra using the LASSO algorithm; then, the parameters are estimated from the extracted features using the support vector regression. On a subsample of 20,000 stellar spectra from the Sloan Digital Sky Survey (SDSS) with reference parameters provided by the SDSS/SEGUE Spectroscopic Parameter Pipeline, estimation consistency are 0.007458 dex for log T{sub eff} (101.609921 K for T{sub eff}), 0.189557 dex for log g, and 0.182060 for [Fe/H], where the consistency is evaluated by mean absolute error. Prominent characteristics of the proposed scheme are sparseness, locality, and physical interpretability. In this work, each spectrum consists of 3821 fluxes, and 10, 19, and 14 typical wavelength positions are detected, respectively, for estimating T{sub eff}, log g, and [Fe/H]. It is shown that the positions are related to typical lines of stellar spectra. This characteristic is important in investigating physical indications from analysis results. Then, stellar spectra can be described by the individual fluxes on the detected positions (PD) or local integration of fluxes near them (LI). The aforementioned consistency is the result based on features described by LI. If features are described by PD, consistency is 0.009092 dex for log T{sub eff} (124.545075 K for T{sub eff}), 0.198928 dex for log g, and 0.206814 dex for [Fe/H].

  5. Novel Characterization of GDI Engine Exhaust for Gasoline and Mid-Level Gasoline-Alcohol Blends

    SciTech Connect (OSTI)

    Storey, John Morse; Lewis Sr, Samuel Arthur; Szybist, James P; Thomas, John F; Barone, Teresa L; Eibl, Mary A; Nafziger, Eric J; Kaul, Brian C

    2014-01-01

    Gasoline direct injection (GDI) engines can offer improved fuel economy and higher performance over their port fuel-injected (PFI) counterparts, and are now appearing in increasingly more U.S. and European vehicles. Small displacement, turbocharged GDI engines are replacing large displacement engines, particularly in light-duty trucks and sport utility vehicles, in order for manufacturers to meet more stringent fuel economy standards. GDI engines typically emit the most particulate matter (PM) during periods of rich operation such as start-up and acceleration, and emissions of air toxics are also more likely during this condition. A 2.0 L GDI engine was operated at lambda of 0.91 at typical loads for acceleration (2600 rpm, 8 bar BMEP) on three different fuels; an 87 anti-knock index (AKI) gasoline (E0), 30% ethanol blended with the 87 AKI fuel (E30), and 48% isobutanol blended with the 87 AKI fuel. E30 was chosen to maximize octane enhancement while minimizing ethanol-blend level and iBu48 was chosen to match the same fuel oxygen level as E30. Particle size and number, organic carbon and elemental carbon (OC/EC), soot HC speciation, and aldehydes and ketones were all analyzed during the experiment. A new method for soot HC speciation is introduced using a direct, thermal desorption/pyrolysis inlet for the gas chromatograph (GC). Results showed high levels of aromatic compounds were present in the PM, including downstream of the catalyst, and the aldehydes were dominated by the alcohol blending.

  6. Improving the Understanding of Intake and Charge Effects for Increasing RCCI Engine Efficiency

    SciTech Connect (OSTI)

    Splitter, Derek A; Reitz, Rolf; Wissink, martin; DelVescovo, Dan

    2014-01-01

    The present experimental engine efficiency study explores the effects of intake pressure and temperature, and premixed and global equivalence ratios on gross thermal efficiency (GTE) using the reactivity controlled compression ignition (RCCI) combustion strategy. Experiments were conducted in a heavy-duty single-cylinder engine at constant net load (IMEPn) of 8.45 bar, 1300 rev/min engine speed, with 0% EGR, and a 50% mass fraction burned combustion phasing (CA50) of 0.5 CA ATDC. The engine was port fueled with E85 for the low reactivity fuel and direct injected with 3.5% 2-ethylhexyl nitrate (EHN) doped into 91 anti-knock index (AKI) gasoline for the high-reactivity fuel. The resulting reactivity of the enhanced fuel corresponds to an AKI of approximately 56 and a cetane number of approximately 28. The engine was operated with a wide range of intake pressures and temperatures, and the ratio of low- to high-reactivity fuel was adjusted to maintain a fixed speed-phasing-load condition. This allowed for the investigation of several combinations of intake temperature, intake pressure, and charge stratification at otherwise constant thermodynamic conditions. The results show that sources of engine inefficiency compete as functions of premixed and global equivalence ratios. Losses are minimized through proper balancing of intake pressure and temperature, such that the global equivalence ratio ( global) is as lean as possible without overly lean regions of the stratified charge causing an increase in incomplete combustion. The explored speed-load-phasing combination shows that losses are minimized at conditions where approximately 2/3 of the fuel is fully premixed. The results exhibit a pathway for achieving simultaneous increases in combustion and fuel efficiency through proper fuel reactivity and initial condition management.

  7. Reverberation measurements of the inner radius of the dust torus in 17 Seyfert galaxies

    SciTech Connect (OSTI)

    Koshida, Shintaro [Center of Astro Engineering and Department of Electrical Engineering, Pontificia Univercsidad Catolica de Chile, Av. Vicuna Mackenna 4868 (Chile); Minezaki, Takeo; Yoshii, Yuzuru; Sakata, Yu; Sugawara, Shota [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Kobayashi, Yukiyasu; Suganuma, Masahiro [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Enya, Keigo [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Tomita, Hiroyuki; Aoki, Tsutomu [Kiso Observatory, Institute of Astronomy, School of Science, University of Tokyo, 10762-30 Mitake, Kiso, Nagano 397-0101 (Japan); Peterson, Bruce A., E-mail: skoshida@ing.puc.cl, E-mail: minezaki@ioa.s.u-tokyo.ac.jp [Mount Stromlo Observatory, Research School of Astronomy and Astrophysics, Australian National University, Weston Creek P.O., ACT 2611 (Australia)

    2014-06-20

    We present the results of a dust reverberation survey for 17 nearby Seyfert 1 galaxies, which provides the largest homogeneous data collection for the radius of the innermost dust torus. A delayed response of the K-band light curve after the V-band light curve was found for all targets, and 49 measurements of lag times between the flux variation of the dust emission in the K band and that of the optical continuum emission in the V band were obtained by the cross-correlation function analysis and also by an alternative method for estimating the maximum likelihood lag. The lag times strongly correlated with the optical luminosity in the luminosity range of M{sub V} = –16 to –22 mag, and the regression analysis was performed to obtain the correlation log ?t (days) = –2.11 – 0.2 M{sub V} assuming ?t?L {sup 0.5}, which was theoretically expected. We discuss the possible origins of the intrinsic scatter of the dust lag-luminosity correlation, which was estimated to be approximately 0.13 dex, and we find that the difference of internal extinction and delayed response of changes in lag times to the flux variations could have partly contributed to intrinsic scatter. However, we could not detect any systematic change of the correlation with the subclass of the Seyfert type or the Eddington ratio. Finally, we compare the dust reverberation radius with the near-infrared interferometric radius of the dust torus and the reverberation radius of broad Balmer emission lines. The interferometric radius in the K band was found to be systematically larger than the dust reverberation radius in the same band by the about a factor of two, which could be interpreted by the difference between the flux-weighted radius and response-weighted radius of the innermost dust torus. The reverberation radius of the broad Balmer emission lines was found to be systematically smaller than the dust reverberation radius by about a factor of four to five, which strongly supports the unified scheme of the Seyfert type of active galactic nuclei (AGNs). Moreover, we examined the radius-luminosity correlations for the hard X-ray (14-195 keV) and the [O IV] ?25.89 ?m emission-line luminosities, which would be applicable for obscured AGNs.

  8. Population Synthesis in the Blue III. The Integrated Spectrum of M67 and the Spectroscopic Age of M32

    E-Print Network [OSTI]

    Ricardo P. Schiavon; Nelson Caldwell; James A. Rose

    2003-12-05

    We construct an integrated spectrum of the intermediate age, solar metallicity Galactic cluster M67, from individual spectra of cluster members. The integrated spectrum is used as a template to test our stellar population synthesis (SPS) models, in an age and [Fe/H] regime where such models remain largely untested. We show that our models predict a spectroscopic age of 3.5 +/- 0.5 Gyr for M67, in excellent agreement with the age we derive from the color-magnitude diagram of the cluster. The same age is obtained when using Hbeta, Hgamma or Hdelta as the age indicator. Our models predict the abundances of Fe, Mg, C and N in agreement with detailed abundance analyses of cluster stars, to within 0.1 dex. Encouraged by the high degree of consistency of our models, we apply them to the study of the integrated spectrum of the central 3 arcsec of the compact elliptical galaxy M32. The resulting luminosity-weighted age of the galaxy ranges between 2 and 3.5 Gyr, depending on the Balmer line used. According to our models, the center of M32 seems to have a super-solar light-weighted Fe abundance, ranging between [Fe/H] ~ +0.1 and +0.3, depending on the Fe line adopted. Light-weighted abundance ratios found for the center of M32 are as follows: [Mg/Fe] ~ -0.1 -- -0.2, [C/Fe] and [N/Fe] ~ 0. We find that single SPS models with a solar-scaled abundance pattern cannot fit all the Balmer and metal lines in the integrated spectrum of M32. There is a systematic trend in the sense that bluer absorption lines indicate a younger age and a higher [Fe/H]. This slight inconsistency can be due either to (unaccounted for) abundance ratio effects on blue iron and Balmer line indices, or to a spread of the ages of the stellar populations in M32. Current stellar population models cannot break this degeneracy at the level of accuracy required to address this problem.

  9. Metallicities on the Double Main Sequence of omega Centauri Imply Large Helium Enhancement

    E-Print Network [OSTI]

    Piotto, G; Bedin, L R; Gratton, R; Cassisi, S; Momany, Y; Recio-Blanco, A; Lucatello, S; Anderson, J; King, I R; Pietrinferni, A; Carraro, G; Piotto, Giampaolo; Villanova, Sandro; Bedin, Luigi R.; Gratton, Raffaele; Cassisi, Santi; Momany, Yazan; Recio-Blanco, Alejandra; Lucatello, Sara; Anderson, Jay; King, Ivan R.; Pietrinferni, Adriano; Carraro, Giovanni

    2004-01-01

    Having shown in a recent paper that the main sequence of omega Centauri is split into two distinct branches, we now present spectroscopic results showing that the bluer sequence is_less_ metal-poor. We have carefully combined GIRAFFE@VLT spectra of 17 stars on each side of the split into a single spectrum for each branch, with adequate S/N to show clearly that the stars of the blue main sequence are less metal poor by 0.3 dex than those of the dominant red one. From an analysis of the individual spectra, we could not detect any abundance spread among the blue main sequence stars, while the red main sequence stars show a 0.2 dex spread in metallicity. We use stellar-structure models to show that only greatly enhanced helium can explain the color difference between the two main sequences, and we discuss ways in which this enhancement could have arisen.

  10. Metallicities on the Double Main Sequence of omega Centauri Imply Large Helium Enhancement

    E-Print Network [OSTI]

    Giampaolo Piotto; Sandro Villanova; Luigi R. Bedin; Raffaele Gratton; Santi Cassisi; Yazan Momany; Alejandra Recio-Blanco; Sara Lucatello; Jay Anderson; Ivan R. King; Adriano Pietrinferni; Giovanni Carraro; .

    2004-12-01

    Having shown in a recent paper that the main sequence of omega Centauri is split into two distinct branches, we now present spectroscopic results showing that the bluer sequence is_less_ metal-poor. We have carefully combined GIRAFFE@VLT spectra of 17 stars on each side of the split into a single spectrum for each branch, with adequate S/N to show clearly that the stars of the blue main sequence are less metal poor by 0.3 dex than those of the dominant red one. From an analysis of the individual spectra, we could not detect any abundance spread among the blue main sequence stars, while the red main sequence stars show a 0.2 dex spread in metallicity. We use stellar-structure models to show that only greatly enhanced helium can explain the color difference between the two main sequences, and we discuss ways in which this enhancement could have arisen.

  11. ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline

    E-Print Network [OSTI]

    Pérez, Ana E García; Holtzman, Jon A; Shetrone, Matthew; Mészáros, Szabolcs; Bizyaev, Dmitry; Carrera, Ricardo; Cunha, Katia; García-Hernández, D A; Johnson, Jennifer A; Majewski, Steven R; Nidever, David L; Schiavon, Ricardo P; Shane, Neville; Smith, Verne V; Sobeck, Jennifer; Troup, Nicholas; Zamora, Olga; Bovy, Jo; Eisenstein, Daniel J; Feuillet, Diane; Frinchaboy, Peter M; Hayden, Michael R; Hearty, Fred R; Nguyen, Duy C; O'Connell, Robert W; Pinsonneault, Marc H; Weinberg, David H; Wilson, John C; Zasowski, Gail

    2015-01-01

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has built the largest moderately high-resolution (R=22, 500) spectroscopic map of the stars across the Milky Way, and including dust-obscured areas. The APOGEE Stellar Parameter and Chemical Abundances Pipeline (ASPCAP) is the software developed for the automated analysis of these spectra. ASPCAP determines atmospheric parameters and chemical abundances from observed spectra by comparing observed spectra to libraries of theoretical spectra, using chi-2 minimization in a multidimensional parameter space. The package consists of a fortran90 code that does the actual minimization, and a wrapper IDL code for book-keeping and data handling. This paper explains in detail the ASPCAP components and functionality, and presents results from a number of tests designed to check its performance. ASPCAP provides stellar effective temperatures, surface gravities, and metallicities precise to 2%, 0.1 dex, and 0.05 dex, respectively, for most APOGEE stars, wh...

  12. NGC 7789: An open cluster case study

    SciTech Connect (OSTI)

    Overbeek, Jamie C.; Friel, Eileen D.; Pilachowski, Catherine A.; Mészáros, Szabolcs [Indiana University Astronomy Department, Swain West 319, 727 East 3rd Street, Bloomington, IN 47405 (United States); Jacobson, Heather R. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Johnson, Christian I., E-mail: joverbee@indiana.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2015-01-01

    We have obtained high-resolution spectra of 32 giants in the open cluster NGC 7789 using the Wisconsin–Indiana–Yale–NOAO Hydra spectrograph. We explore differences in atmospheric parameters and elemental abundances caused by the use of the linelist developed for the Gaia-ESO Survey (GES) compared to one based on Arcturus used in our previous work. [Fe/H] values decrease when using the GES linelist instead of the Arcturus-based linelist; these differences are probably driven by systematically lower (??0.1 dex) GES surface gravities. Using the GES linelist we determine abundances for 10 elements—Fe, Mg, Si, Ca, Ti, Na, Ni, Zr, Ba, and La. We find the cluster's average metallicity [Fe/H] = 0.03 ± 0.07 dex, in good agreement with literature values, and a lower [Mg/Fe] abundance than has been reported before for this cluster (0.11 ± 0.05 dex). We also find the neutron-capture element barium to be highly enhanced—[Ba/Fe] = +0.48 ± 0.08—and disparate from cluster measurements of neutron-capture elements La and Zr (?0.08 ± 0.05 and 0.08 ± 0.08, respectively). This is in accordance with recent discoveries of supersolar Ba enhancement in young clusters along with more modest enhancement of other neutron-capture elements formed in similar environments.

  13. The Gas Phase Mass Metallicity Relation for Dwarf Galaxies: Dependence on Star Formation Rate and HI Gas Mass

    E-Print Network [OSTI]

    Jimmy,; Saintonge, Amélie; Accurso, Gioacchino; Brough, Sarah; Oliva-Altamirano, Paola

    2015-01-01

    Using a sample of dwarf galaxies observed using the VIMOS IFU on the VLT, we investigate the mass-metallicity relation (MZR) as a function of star formation rate (FMR$_{\\text{SFR}}$) as well as HI-gas mass (FMR$_{\\text{HI}}$). We combine our IFU data with a subsample of galaxies from the ALFALFA HI survey crossmatched to the Sloan Digital Sky Survey to study the FMR$_{\\text{SFR}}$ and FMR$_{\\text{HI}}$ across the stellar mass range 10$^{6.6}$ to 10$^{8.8}$ M$_\\odot$, with metallicities as low as 12+log(O/H) = 7.67. We find the 1$\\sigma$ mean scatter in the MZR to be 0.05 dex. The 1$\\sigma$ mean scatter in the FMR$_{\\text{SFR}}$ (0.02 dex) is significantly lower than that of the MZR. The FMR$_{\\text{SFR}}$ is not consistent between the IFU observed galaxies and the ALFALFA/SDSS galaxies for SFRs lower than 10$^{-2.4}$ M$_\\odot$ yr$^{-1}$, however this could be the result of limitations of our measurements in that regime. The lowest mean scatter (0.01 dex) is found in the FMR$_{\\text{HI}}$. We also find that th...

  14. Carbon abundances of the reference late-type stars from 1D analysis of atomic C I and molecular CH lines

    E-Print Network [OSTI]

    Alexeeva, S A

    2015-01-01

    A comprehensive model atom was constructed for C I using the most up-to-date atomic data. We evaluated non-local thermodynamical equilibrium (NLTE) line formation for neutral carbon in classical 1D models representing atmospheres of late-type stars, where carbon abundance varies from solar value down to [C/H] = $-$3. NLTE leads to stronger C I lines compared with their LTE strength and negative NLTE abundance corrections, $\\Delta_{\\rm NLTE}$. The deviations from LTE are large for the strong lines in the infrared (IR), with $\\Delta_{\\rm NLTE}$ = $-$0.10 dex to $-$0.45 dex depending on stellar parameters, and they are minor for the weak lines in the visible spectral range, with |$\\Delta_{\\rm NLTE}| \\le$ 0.03 dex. The NLTE abundance corrections were found to be dependent of the carbon abundance in the model. As the first application of the treated model atom, carbon NLTE abundances were determined for the Sun and eight late-type stars with well-determined stellar parameters that cover the $-2.56 \\le$ [Fe/H] $\\le...

  15. TRACING THE ORPHAN STREAM TO 55 kpc WITH RR LYRAE STARS

    SciTech Connect (OSTI)

    Sesar, Branimir; Cohen, Judith G.; Bellm, Eric C.; Levitan, David; Tang, Sumin; Waszczak, Adam; Kulkarni, Shrinivas R.; Prince, Thomas A.; Grillmair, Carl J.; Laher, Russ R.; Surace, Jason A.; Bhalerao, Varun B.; Ofek, Eran O.

    2013-10-10

    We report positions, velocities, and metallicities of 50 ab-type RR Lyrae (RRab) stars observed in the vicinity of the Orphan stellar stream. Using about 30 RRab stars classified as being likely members of the Orphan stream, we study the metallicity and the spatial extent of the stream. We find that RRab stars in the Orphan stream have a wide range of metallicities, from –1.5 dex to –2.7 dex. The average metallicity of the stream is –2.1 dex, identical to the value obtained by Newberg et al. using blue horizontal branch stars. We find that the most distant parts of the stream (40-50 kpc from the Sun) are about 0.3 dex more metal-poor than the closer parts (within ?30 kpc), suggesting a possible metallicity gradient along the stream's length. We have extended the previous studies and have mapped the stream up to 55 kpc from the Sun. Even after a careful search, we did not identify any more distant RRab stars that could plausibly be members of the Orphan stream. If confirmed with other tracers, this result would indicate a detection of the end of the leading arm of the stream. We have compared the distances of Orphan stream RRab stars with the best-fit orbits obtained by Newberg et al. We find that model 6 of Newberg et al. cannot explain the distances of the most remote Orphan stream RRab stars, and conclude that the best fit to distances of Orphan stream RRab stars and to the local circular velocity is provided by potentials where the total mass of the Galaxy within 60 kpc is M{sub 60} ? 2.7 × 10{sup 11} M{sub ?}, or about 60% of the mass found by previous studies. More extensive modeling that would consider non-spherical potentials and the possibility of misalignment between the stream and the orbit is highly encouraged.

  16. Study Agriculture Abroad Check with the Study Abroad office for up to date costs, course restrictions, and application processes.

    E-Print Network [OSTI]

    Barge, Marcy

    )* Australia - University of Western Australia (DEX) La Trobe University - Melbourne (ISEP) Finland Australia (DEX) La Trobe University - Melbourne (ISEP) Finland - University of Turku (ISEP) Univeristy) Sustainable Food & Bioenergy Systems Argentina - Universidad de Belgrano (CCIS)* Universidad del Salvador

  17. Ceci N'est Pas a globular cluster: the metallicity distribution of the stellar system Terzan 5

    SciTech Connect (OSTI)

    Massari, D.; Mucciarelli, A.; Ferraro, F. R.; Lanzoni, B.; Dalessandro, E.; Lovisi, L. [Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, v.le Berti Pichat 6/2, I-40127 Bologna (Italy); Origlia, L.; Bellazzini, M. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Rich, R. M.; Reitzel, D. [Department of Physics and Astronomy, Math-Sciences 8979, UCLA, Los Angeles, CA 90095-1562 (United States); Valenti, E. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany); Ibata, R. [Observatoire Astronomique, Université de Strasbourg, CNRS, 11, rue de l'Université. F-67000 Strasbourg (France)

    2014-11-01

    We present new determinations of the iron abundance for 220 stars belonging to the stellar system Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this stellar system. From this data set, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the system has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H] ? 0.25 dex, accounting for ?29% of the sample, a dominant sub-solar population at [Fe/H] ? –0.30 dex, corresponding to ?62% of the total, and a minor (6%) metal-poor component at [Fe/H] ? –0.8 dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex stellar system.

  18. Ultraluminous infrared galaxies in the AKARI all-sky survey

    SciTech Connect (OSTI)

    Kilerci Eser, E., E-mail: ecekilerci@dark-cosmology.dk [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø (Denmark); Goto, T. [National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Doi, Y., E-mail: tomo@phys.nthu.edu.tw, E-mail: doi@ea.c.u-tokyo.ac.jp [The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902 (Japan)

    2014-12-10

    We present a new catalog of 118 ultraluminous infrared galaxies (ULIRGs) and one hyperluminous infrared galaxy (HLIRG) by cross-matching the AKARI all-sky survey with the Sloan Digital Sky Survey Data Release 10 (SDSS DR10) and the final data release of the Two-Degree Field Galaxy Redshift Survey. Forty of the ULIRGs and one HLIRG are new identifications. We find that ULIRGs are interacting pair galaxies or ongoing or postmergers. This is consistent with the widely accepted view: ULIRGs are major mergers of disk galaxies. We confirm the previously known positive trend between the active galactic nucleus fraction and infrared luminosity. We show that ULIRGs have a large offset from the main sequence up to z ? 1; their offset from the z ? 2 'main sequence' is relatively smaller. We find a result consistent with the previous studies showing that, compared to local star-forming SDSS galaxies of similar mass, local ULIRGs have lower oxygen abundances. We demonstrate for the first time that ULIRGs follow the fundamental metallicity relation (FMR). The scatter of ULIRGs around the FMR (0.09 dex-0.5 dex) is comparable to the scatter of z ? 2-3 galaxies. We provide the largest local (0.050

  19. Measuring Ages and Elemental Abundances from Unresolved Stellar Populations: Fe, Mg, C, N, and Ca

    E-Print Network [OSTI]

    Genevieve J. Graves; Ricardo P. Schiavon

    2008-03-10

    We present a method for determining mean light-weighted ages and abundances of Fe, Mg, C, N, and Ca, from medium resolution spectroscopy of unresolved stellar populations. The method, pioneered by Schiavon (2007), is implemented in a publicly available code called EZ_Ages. The method and error estimation are described, and the results tested for accuracy and consistency, by application to integrated spectra of well-known Galactic globular and open clusters. Ages and abundances from integrated light analysis agree with studies of resolved stars to within +/-0.1 dex for most clusters, and to within +/-0.2 dex for nearly all cases. The results are robust to the choice of Lick indices used in the fitting to within +/-0.1 dex, except for a few systematic deviations which are clearly categorized. The realism of our error estimates is checked through comparison with detailed Monte Carlo simulations. Finally, we apply EZ_Ages to the sample of galaxies presented in Thomas et al. (2005) and compare our derived values of age, [Fe/H], and [alpha/Fe] to their analysis. We find that [alpha/Fe] is very consistent between the two analyses, that ages are consistent for old (Age > 10 Gyr) populations, but show modest systematic differences at younger ages, and that [Fe/H] is fairly consistent, with small systematic differences related to the age systematics. Overall, EZ_Ages provides accurate estimates of fundamental parameters from medium resolution spectra of unresolved stellar populations in the old and intermediate-age regime, for the first time allowing quantitative estimates of the abundances of C, N, and Ca in these unresolved systems. The EZ_Ages code can be downloaded at http://www.ucolick.org/~graves/EZ_Ages.html

  20. Single-epoch black hole mass estimators for broad-line active galactic nuclei: recalibrating H? with a new approach

    SciTech Connect (OSTI)

    Feng, Hua; Li, Hong [Department of Engineering Physics and Center for Astrophysics, Tsinghua University, Beijing 100084 (China); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2014-10-10

    Based on an updated H? reverberation mapping (RM) sample of 44 nearby active galactic nuclei (AGNs), we propose a novel approach for black hole (BH) mass estimation using two filtered luminosities computed from single-epoch (SE) AGN spectra around the H? region. We found that the two optimal-filter luminosities extract virial information (size and virial velocity of the broad-line region, BLR) from the spectra, justifying their usage in this empirical BH mass estimator. The major advantages of this new recipe over traditional SE BH mass estimators utilizing continuum luminosity and broad-line width are (1) it has a smaller intrinsic scatter of 0.28 dex calibrated against RM masses, (2) it is extremely simple to use in practice, without any need to decompose the spectrum, and (3) it produces unambiguous and highly repeatable results even with low signal-to-noise spectra. The combination of the two luminosities can also cancel out, to some extent, systematic luminosity errors potentially introduced by uncertainties in distance or flux calibration. In addition, we recalibrated the traditional SE mass estimators using broad H? FWHM and monochromatic continuum luminosity at 5100 Å (L {sub 5100}). We found that using the best-fit slopes on FWHM and L {sub 5100} (derived from fitting the BLR radius-luminosity relation and the correlation between rms line dispersion and SE FWHM, respectively) rather than simple assumptions (e.g., 0.5 for L {sub 5100} and 2 for FWHM) leads to more precise SE mass estimates, improving the intrinsic scatter from 0.41 dex to 0.36 dex with respect to the RM masses. We compared different estimators and discussed their applications to the Sloan Digital Sky Survey quasar sample. Due to the limitations of the current RM sample, application of any SE recipe calibrated against RM masses to distant quasars should be treated with caution.

  1. Urban Sewage Delivery Heat Transfer System (1): Flow Resistance and Energy Analysis 

    E-Print Network [OSTI]

    Zhang, C.; Wu, R.; Li, G.; Li, X.; Huang, L.; Sun, D.

    2006-01-01

    , Shenzhen, China Renewable Energy Resources and a Greener Future Vol.VIII-8-4 Urban Sewage Delivery Heat Transfer System (1): Flow Resistance and Energy Analysis1 Chenghu Zhang Ronghua Wu Guitao Li Xin Li Lei Huang Dexing Sun Doctor Master...) By the numeric calculation and the simplification, the power function form, can be obtained, which is used in the engineering easily. It is 0.30 0.0235 w d? = (2) The result of (2) is slight bigger than that of (1), but the errors are within 3...

  2. Accurate atmospheric parameters at moderate resolution using spectral indices: Preliminary application to the marvels survey

    SciTech Connect (OSTI)

    Ghezzi, Luan; Da Costa, Luiz N.; Maia, Marcio A. G.; Ogando, Ricardo L. C.; Dutra-Ferreira, Letícia; Lorenzo-Oliveira, Diego; Porto de Mello, Gustavo F.; Santiago, Basílio X.; De Lee, Nathan; Lee, Brian L.; Ge, Jian; Wisniewski, John P.; González Hernández, Jonay I.; Stassun, Keivan G.; Cargile, Phillip; Pepper, Joshua; Fleming, Scott W.; Schneider, Donald P.; Mahadevan, Suvrath; Wang, Ji; and others

    2014-12-01

    Studies of Galactic chemical, and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (effective temperature T {sub eff}, metallicity [Fe/H], and surface gravity log g) for solar-type stars. Many large-scale spectroscopic surveys operate at low to moderate spectral resolution for efficiency in observing large samples, which makes the stellar characterization difficult due to the high degree of blending of spectral features. Therefore, most surveys employ spectral synthesis, which is a powerful technique, but relies heavily on the completeness and accuracy of atomic line databases and can yield possibly correlated atmospheric parameters. In this work, we use an alternative method based on spectral indices to determine the atmospheric parameters of a sample of nearby FGK dwarfs and subgiants observed by the MARVELS survey at moderate resolving power (R ? 12,000). To avoid a time-consuming manual analysis, we have developed three codes to automatically normalize the observed spectra, measure the equivalent widths of the indices, and, through a comparison of those with values calculated with predetermined calibrations, estimate the atmospheric parameters of the stars. The calibrations were derived using a sample of 309 stars with precise stellar parameters obtained from the analysis of high-resolution FEROS spectra, permitting the low-resolution equivalent widths to be directly related to the stellar parameters. A validation test of the method was conducted with a sample of 30 MARVELS targets that also have reliable atmospheric parameters derived from the high-resolution spectra and spectroscopic analysis based on the excitation and ionization equilibria method. Our approach was able to recover the parameters within 80 K for T {sub eff}, 0.05 dex for [Fe/H], and 0.15 dex for log g, values that are lower than or equal to the typical external uncertainties found between different high-resolution analyses. An additional test was performed with a subsample of 138 stars from the ELODIE stellar library, and the literature atmospheric parameters were recovered within 125 K for T {sub eff}, 0.10 dex for [Fe/H], and 0.29 dex for log g. These precisions are consistent with or better than those provided by the pipelines of surveys operating with similar resolutions. These results show that the spectral indices are a competitive tool to characterize stars with intermediate resolution spectra.

  3. Characterizing the AB Doradus moving group via high-resolution spectroscopy and kinematic traceback

    SciTech Connect (OSTI)

    McCarthy, Kyle; Wilhelm, Ronald J.

    2014-10-01

    We present a detailed analysis of 10 proposed F and G members of the nearby, young moving group AB Doradus (ABD). Our sample was obtained using the 2.7 m telescope at the McDonald Observatory with the coude echelle spectrograph, achieving R ? 60,000 and signal-to-noise ratio ?200. We derive spectroscopic T {sub eff}, log(g), [Fe/H], and microturbulance (v{sub t} ) using a bootstrap method of the TGVIT software resulting in typical errors of 33K in T {sub eff}, 0.08 dex in log(g), 0.03 dex in [Fe/H], and 0.13 km s{sup –1} in v{sub t} . Characterization of the ABD sample is performed in three ways: (1) chemical homogeneity, (2) kinematic traceback, and (3) isochrone fitting. We find the average metal abundance is [M/H] = –0.03 ± 0.06 with a traceback age of 125 Myr. Our stars were fit to three different evolutionary models and we found that the best match to our ABD sample is the YREC [M/H] = –0.1 model. In our sample of 10 stars, we identify 1 star that is a probable non-member, 3 enigmatic stars, and 6 stars with confirmed membership. We also present a list of chemically coherent stars from this study and the Barenfeld et al. study.

  4. The Nature and Orbit of the Ophiuchus Stream

    E-Print Network [OSTI]

    Sesar, B; Bernard, E J; Caldwell, N; Cohen, J G; Fouesneau, M; Johnson, C I; Ness, M; Ferguson, A M N; Martin, N F; Rix, H -W; Schlafly, E F; Burgett, W S; Chambers, K C; Flewelling, H; Hodapp, K W; Kaiser, N; Magnier, E A; Platais, I; Tonry, J L; Waters, C; Wyse, R F G

    2015-01-01

    The Ophiuchus stream is the most recently discovered stellar tidal stream in the Milky Way (Bernard et al. 2014). We present high-quality spectroscopic data for 14 stream member stars obtained using the Keck and MMT telescopes. We confirm the stream as a fast moving ($v_{los}\\sim290$ km s$^{-1}$), kinematically-cold group ($\\sigma_{v_{los}}\\lesssim1$ km s$^{-1}$) of $\\alpha-$enhanced and metal-poor stars (${\\rm [\\alpha/Fe]\\sim0.4}$ dex, ${\\rm [Fe/H]\\sim-2.0}$ dex). Using a probabilistic technique, we model the stream simultaneously in line-of-sight velocity, color-magnitude, coordinate, and proper motion space, and so determine its distribution in 6D phase-space. We find that that the stream extends in distance from 8 to 9.5 kpc from the Sun; it is 50 times longer than wide, merely appearing highly foreshortened in projection. The analysis of the stellar population contained in the stream suggests that it is $\\sim13$ Gyr old, and that its initial stellar mass was $\\sim2\\times10^4$ $M_\\sun$ (or at least $\\ga4\\...

  5. Segue 1 - A Compressed Star Formation History Before Reionization

    E-Print Network [OSTI]

    Webster, David; Bland-Hawthorn, Joss

    2015-01-01

    Segue 1 is the current best candidate for a "first galaxy", a system which experienced only a single short burst of star formation and has since remained unchanged. Here we present possible star formation scenarios which can explain its unique metallicity distribution. While the majority of stars in all other ultra-faint dwarfs (UFDs) are within 0.5 dex of the mean [Fe/H] for the galaxy, 5 of the 7 stars in Segue 1 have a spread of $\\Delta$[Fe/H] $>0.8$ dex. We show that this distribution of metallicities canot be explained by a gradual build-up of stars, but instead requires clustered star formation. Chemical tagging allows the separate unresolved delta functions in abundance space to be associated with discrete events in space and time. This provides an opportunity to put the enrichment events into a time sequence and unravel the history of the system. We investigate two possible scenarios for the star formation history of Segue 1 using Fyris Alpha simulations of gas in a $10^7$ M$_\\odot$ dark matter halo. ...

  6. The Giraffe Inner Bulge Survey (GIBS) II. Metallicity distributions and alpha element abundances at fixed Galactic latitude

    E-Print Network [OSTI]

    Gonzalez, O A; Vasquez, S; Hill, V; Rejkuba, M; Valenti, E; Rojas-Arriagada, A; Renzini, A; Babusiaux, C; Minniti, D; Brown, T M

    2015-01-01

    High resolution (R$\\sim$22,500) spectra for 400 red clump giants, in four fields within $\\rm -4.8^{\\circ} \\lesssim b \\lesssim -3.4^{\\circ}$ and $\\rm -10^{\\circ} \\lesssim l \\lesssim +10^{\\circ}$, were obtained within the GIRAFFE Inner Bulge Survey (GIBS) project. To this sample we added another $\\sim$ 400 stars in Baade's Window, observed with the identical instrumental configuration. We constructed the metallicity distributions for the entire sample, as well as for each field individually, in order to investigate the presence of gradients or field-to-field variations in the shape of the distributions. The metallicity distributions in the five fields are consistent with being drawn from a single parent population, indicating the absence of a gradient along the major axis of the Galactic bar. The global metallicity distribution is well fitted by two Gaussians. The metal poor component is rather broad, with a mean at $\\rm =-0.31$ dex and $\\sigma=0.31$ dex. The metal-rich one is narrower, with mean $\\rm =+0.26$ a...

  7. The First Billion Years of a Warm Dark Matter Universe

    E-Print Network [OSTI]

    Maio, Umberto

    2014-01-01

    We present results of cosmological N-body hydrodynamic chemistry simulations of primordial structure growth and evolution in a scenario with warm dark matter (WDM) having a mass of 3keV and compare with a model consisting of standard cold dark matter (CDM). We focus on the high-redshift universe ($z>6$), where the structure formation process should better reflect the primordial (linear) differences in terms of matter power spectrum. We find that early epochs are exceptional probes of the dark-matter nature. Non-linear CDM and WDM power spectra differ by up to 2 dex at early times and show spreads of factor of a few persisting in the whole first Gyr. Primordial WDM objects with masses $\\lesssim 10^8\\,\\rm M_\\odot$ are less abundant by $\\gtrsim 1\\,\\rm dex$, both in terms of dark matter and of baryon content. Runaway molecular cooling in primordial WDM mini-haloes results severely inhibited due to the damping of power at large $k$ modes. As a consequence, the cosmic (population III and II-I) star formation activi...

  8. The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic Globular and Open Clusters

    E-Print Network [OSTI]

    Y. S. Lee; T. C. Beers; T. Sivarani; J. A. Johnson; D. An; R. Wilhelm; C. Allende Prieto; L. Koesterke; P. Re Fiorentin; C. A. L. Bailer-Jones; J. E. Norris; B. Yanny; C. M. Rockosi; H. J. Newberg; K. M. Cudworth; K. Pan

    2007-10-31

    We validate the performance and accuracy of the current SEGUE (Sloan Extension for Galactic Understanding and Exploration) Stellar Parameter Pipeline (SSPP), which determines stellar atmospheric parameters (effective temperature, surface gravity, and metallicity) by comparing derived overall metallicities and radial velocities from selected likely members of three globular clusters (M 13, M 15, and M 2) and two open clusters (NGC 2420 and M 67) to the literature values. Spectroscopic and photometric data obtained during the course of the original Sloan Digital Sky Survey (SDSS-I) and its first extension (SDSS-II/SEGUE) are used to determine stellar radial velocities and atmospheric parameter estimates for stars in these clusters. Based on the scatter in the metallicities derived for the members of each cluster, we quantify the typical uncertainty of the SSPP values, sigma([Fe/H]) = 0.13 dex for stars in the range of 4500 K < Teff < 7500 K and 2.0 < log g < 5.0, at least over the metallicity interval spanned by the clusters studied (-2.3 < [Fe/H] < 0). The surface gravities and effective temperatures derived by the SSPP are also compared with those estimated from the comparison of the color-magnitude diagrams with stellar evolution models; we find satisfactory agreement. At present, the SSPP underestimates [Fe/H] for near-solar-metallicity stars, represented by members of M 67 in this study, by about 0.3 dex.

  9. The solar oxygen crisis: Probably not the last word

    E-Print Network [OSTI]

    H. Socas-Navarro A. A. Norton

    2007-03-26

    In this work we present support for recent claims that advocate a downward revision of the solar oxygen abundance. Our analysis employs spatially-resolved spectro-polarimetric observations including the \\FeI lines at 6302 \\AA and the \\OI infrared triplet around 7774 \\AA in the quiet Sun. We used the \\FeI lines to reconstruct the three-dimensional thermal and magnetic structure of the atmosphere. The simultaneous \\OI observations were then employed to determine the abundance of oxygen at each pixel, using both LTE and non-LTE (NLTE) approaches to the radiative transfer. In this manner, we obtain values of \\lgEO=8.63 (NLTE) and 8.93 (LTE) dex. We find an unsettling fluctuation of the oxygen abundance over the field of view. This is likely an artifact indicating that, even with this relatively refined strategy, important physical ingredients are still missing in the picture. By examining the spatial distribution of the abundance, we estimate realistic confidence limits of approximately 0.1 dex.

  10. The SEGUE Stellar Parameter Pipeline. III. Comparison with High-Resolution Spectroscopy of SDSS/SEGUE Field Stars

    E-Print Network [OSTI]

    C. Allende Prieto; T. Sivarani; T. C. Beers; Y. S. Lee; L. Koesterke; M. Shetrone; C. Sneden; D. L. Lambert; R. Wilhelm; C. M. Rockosi; D. Lai; B. Yanny; I. I. Ivans; J. A. Johnson; W. Aoki; C. A. L. Bailer-Jones; P. Re Fiorentin

    2007-10-31

    We report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which we compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R = 2000) spectroscopy. For F- and G-type stars observed with high signal-to-noise ratios (S/N), we empirically determine the typical random uncertainties in the radial velocities, effective temperatures, surface gravities, and metallicities delivered by the SSPP to be 2.4 km/s, 130 K (2.2%), 0.21 dex, and 0.11 dex, respectively, with systematic uncertainties of a similar magnitude in the effective temperatures and metallicities. We estimate random errors for lower S/N spectra based on numerical simulations.

  11. HUNTING THE PARENT OF THE ORPHAN STREAM: IDENTIFYING STREAM MEMBERS FROM LOW-RESOLUTION SPECTROSCOPY

    SciTech Connect (OSTI)

    Casey, Andrew R.; Da Costa, Gary; Keller, Stefan C.; Maunder, Elizabeth, E-mail: acasey@mso.anu.edu.au [Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, via Cotter Road, Weston, ACT 2611 (Australia)] [Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, via Cotter Road, Weston, ACT 2611 (Australia)

    2013-02-10

    We present candidate K-giant members in the Orphan Stream that have been identified from low-resolution data taken with the AAOmega spectrograph on the Anglo-Australian Telescope. From modest signal-to-noise spectra and independent cuts in photometry, kinematics, gravity, and metallicity we yield self-consistent, highly probable stream members. We find a revised stream distance of 22.5 {+-} 2.0 kpc near the celestial equator and our kinematic signature peaks at V {sub GSR} = 82.1 {+-} 1.4 km s{sup -1}. The observed velocity dispersion of our most probable members is consistent with arising from the velocity uncertainties alone. This indicates that at least along this line of sight, the Orphan Stream is kinematically cold. Our data indicate an overall stream metallicity of [Fe/H] = -1.63 {+-} 0.19 dex which is more metal-rich than previously found and unbiased by spectral type. Furthermore, the significant metallicity dispersion displayed by our most probable members, {sigma}([Fe/H]) = 0.56 dex, suggests that the unidentified Orphan Stream parent is a dSph satellite. We highlight likely members for high-resolution spectroscopic follow-up.

  12. The Milky Way Tomography with SDSS. 2. Stellar Metallicity

    SciTech Connect (OSTI)

    Ivezic, Zeljko; Sesar, Branimir; Juric, Mario; Bond, Nicholas; Dalcanton, Julianne; Rockosi, Constance M.; Yanny, Brian; Newberg, Heidi J.; Beers, Timothy C.; Prieto, Carlos Allende; Wilhelm, Ron; /Texas Tech. /Michigan State U.

    2008-04-01

    In addition to optical photometry of unprecedented quality, the Sloan Digital Sky Survey (SDSS) is producing a massive spectroscopic database which already contains over 280,000 stellar spectra. Using effective temperature and metallicity derived from SDSS spectra for {approx}60,000 F and G type main sequence stars (0.2 < g-r < 0.6), we develop polynomial models, reminiscent of traditional methods based on the UBV photometry, for estimating these parameters from the SDSS u-g and g-r colors. These estimators reproduce SDSS spectroscopic parameters with a root-mean-square scatter of 100 K for effective temperature, and 0.2 dex for metallicity (limited by photometric errors), which are similar to random and systematic uncertainties in spectroscopic determinations. We apply this method to a photometric catalog of coadded SDSS observations and study the photometric metallicity distribution of {approx}200,000 F and G type stars observed in 300 deg{sup 2} of high Galactic latitude sky. These deeper (g < 20.5) and photometrically precise ({approx}0.01 mag) coadded data enable an accurate measurement of the unbiased metallicity distribution for a complete volume-limited sample of stars at distances between 500 pc and 8 kpc. The metallicity distribution can be exquisitely modeled using two components with a spatially varying number ratio, that correspond to disk and halo. The best-fit number ratio of the two components is consistent with that implied by the decomposition of stellar counts profiles into exponential disk and power-law halo components by Juric et al. (2008). The two components also possess the kinematics expected for disk and halo stars. The metallicity of the halo component can be modeled as a spatially invariant Gaussian distribution with a mean of [Fe/H] = -1.46 and a standard deviation of {approx}0.3 dex. The disk metallicity distribution is non-Gaussian, with a remarkably small scatter (rms {approx}0.16 dex) and the median smoothly decreasing with distance from the plane from -0.6 at 500 pc to -0.8 beyond several kpc. Similarly, we find using proper motion measurements that a non-Gaussian rotational velocity distribution of disk stars shifts by {approx}50 km/s as the distance from the plane increases from 500 pc to several kpc. Despite this similarity, the metallicity and rotational velocity distributions of disk stars are not correlated (Kendall's {tau} = 0.017 {+-} 0.018). This absence of a correlation between metallicity and kinematics for disk stars is in a conflict with the traditional decomposition in terms of thin and thick disks, which predicts a strong correlation ({tau} = ?0.30 {+-} 0.04) at {approx}1 kpc from the mid-plane. Instead, the variation of the metallicity and rotational velocity distributions can be modeled using non-Gaussian functions that retain their shapes and only shift as the distance from the mid-plane increases. We also study the metallicity distribution using a shallower (g < 19.5) but much larger sample of close to three million stars in 8500 sq. deg. of sky included in SDSS Data Release 6. The large sky coverage enables the detection of coherent substructures in the kinematics-metallicity space, such as the Monoceros stream, which rotates faster than the LSR, and has a median metallicity of [Fe/H] = ?0.95, with an rms scatter of only {approx}0.15 dex. We extrapolate our results to the performance expected from the Large Synoptic Survey Telescope (LSST) and estimate that the LSST will obtain metallicity measurements accurate to 0.2 dex or better, with proper motion measurements accurate to {approx}0.2-0.5 mas/yr, for about 200 million F/G dwarf stars within a distance limit of {approx}100 kpc (g < 23.5).

  13. TWO DISTANT HALO VELOCITY GROUPS DISCOVERED BY THE PALOMAR TRANSIENT FACTORY

    SciTech Connect (OSTI)

    Sesar, Branimir; Cohen, Judith G.; Levitan, David; Kirby, Evan N.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Grillmair, Carl J.; Laher, Russ R.; Surace, Jason A.; Juric, Mario; Ofek, Eran O.

    2012-08-20

    We report the discovery of two new halo velocity groups (Cancer groups A and B) traced by eight distant RR Lyrae stars and observed by the Palomar Transient Factory survey at R.A. {approx} 129 Degree-Sign , decl. {approx} 20 Degree-Sign (l {approx} 205 Degree-Sign , b {approx} 32 Degree-Sign ). Located at 92 kpc from the Galactic center (86 kpc from the Sun), these are some of the most distant substructures in the Galactic halo known to date. Follow-up spectroscopic observations with the Palomar Observatory 5.1 m Hale telescope and W. M. Keck Observatory 10 m Keck I telescope indicate that the two groups are moving away from the Galaxy at v-bar{sub gsr}{sup A} = 78.0{+-}5.6 km s{sup -1} (Cancer group A) and v-bar{sub gsr}{sup B} = 16.3{+-}7.1 km s{sup -1} (Cancer group B). The groups have velocity dispersions of {sigma}{sub v{sub g{sub s{sub r}{sup A}}}} = 12.4{+-}5.0 km s{sup -1} and {sigma}B{sub v{sub g{sub s{sub r}{sup B}}}} =14.9{+-}6.2 km s{sup -1} and are spatially extended (about several kpc), making it very unlikely that they are bound systems, and more likely to be debris of tidally disrupted dwarf galaxies or globular clusters. Both groups are metal-poor (median metallicities of [Fe/H]{sup A} = -1.6 dex and [Fe/H]{sup B} = -2.1 dex) and have a somewhat uncertain (due to small sample size) metallicity dispersion of {approx}0.4 dex, suggesting dwarf galaxies as progenitors. Two additional RR Lyrae stars with velocities consistent with those of the Cancer groups have been observed {approx}25 Degree-Sign east, suggesting possible extension of the groups in that direction.

  14. The mass-metallicity relation of interacting galaxies

    E-Print Network [OSTI]

    L. Michel-Dansac; D. G. Lambas; M. S. Alonso; P. Tissera

    2008-02-26

    We study the mass-metallicity relation of galaxies in pairs and in isolation taken from the SDSS-DR4 using the stellar masses and oxygen abundances derived by Tremonti et al. (2004). Close galaxy pairs, defined by projected separation r_p ~ 10^10 Msun/h) galaxies have a systematically lower metallicity, although with a smaller difference (-0.05 dex). Similar trends are obtained if g-band magnitudes are used instead of stellar masses. In minor interactions, we find that the less massive member is systematically enriched, while a galaxy in interaction with a comparable stellar mass companion shows a metallicity decrement with respect to galaxies in isolation. We argue that metal-rich starbursts triggered by a more massive component, and inflows of low metallicity gas induced by comparable or less massive companion galaxies, provide a natural scenario to explain our findings.

  15. Galaxy rotation curves with log-normal density distribution

    E-Print Network [OSTI]

    Marr, John H

    2015-01-01

    The log-normal distribution represents the probability of finding randomly distributed particles in a micro canonical ensemble with high entropy. To a first approximation, a modified form of this distribution with a truncated termination may represent an isolated galactic disk, and this disk density distribution model was therefore run to give the best fit to the observational rotation curves for 37 representative galaxies. The resultant curves closely matched the observational data for a wide range of velocity profiles and galaxy types with rising, flat or descending curves in agreement with Verheijen's classification of 'R', 'F' and 'D' type curves, and the corresponding theoretical total disk masses could be fitted to a baryonic Tully Fisher relation (bTFR). Nine of the galaxies were matched to galaxies with previously published masses, suggesting a mean excess dynamic disk mass of dex0.61+/-0.26 over the baryonic masses. Although questionable with regard to other measurements of the shape of disk galaxy g...

  16. Interpreting the Global 21-cm Signal from High Redshifts. II. Parameter Estimation for Models of Galaxy Formation

    E-Print Network [OSTI]

    Mirocha, Jordan; Burns, Jack O

    2015-01-01

    Following our previous work, which related generic features in the sky-averaged (global) 21-cm signal to properties of the intergalactic medium, we now investigate the prospects for constraining a simple galaxy formation model with current and near-future experiments. Markov-Chain Monte Carlo fits to our synthetic dataset, which includes a realistic galactic foreground, a plausible model for the signal, and noise consistent with 100 hours of integration by an ideal instrument, suggest that a simple four-parameter model that links the production rate of Lyman-$\\alpha$, Lyman-continuum, and X-ray photons to the growth rate of dark matter halos can be well-constrained (to $\\sim 0.1$ dex in each dimension) so long as all three spectral features expected to occur between $40 \\lesssim \

  17. Red Supergiants as Cosmic Abundance Probes: The Sculptor Galaxy NGC 300

    E-Print Network [OSTI]

    Gazak, J Zachary; Evans, Chris; Patrick, Lee; Davies, Ben; Bergemann, Maria; Plez, Bertrand; Bresolin, Fabio; Bender, Ralf; Wegner, Michael; Bonanos, Alceste Z; Williams, Stephen J

    2015-01-01

    We present a quantitative spectroscopic study of twenty-seven red supergiants in the Sculptor Galaxy NGC 300. J-band spectra were obtained using KMOS on the VLT and studied with state of the art synthetic spectra including NLTE corrections for the strongest diagnostic lines. We report a central metallicity of [Z]= -0.03 +/- 0.05 with a gradient of -0.083 +/- 0.014 [dex/kpc], in agreement with previous studies of blue supergiants and H II-region auroral line measurements. This result marks the first application of the J-band spectroscopic method to a population of individual red supergiant stars beyond the Local Group of galaxies and reveals the great potential of this technique.

  18. The Effect of Metallicity on Cepheid-Based Distances

    E-Print Network [OSTI]

    Shoko Sakai; Laura Ferrarese; Rob Kennicutt; Abi Saha

    2004-02-20

    We have used the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope to obtain V and I images of seven nearby galaxies. For each, we have measured a distance using the tip of the red giant branch (TRGB) method. By comparing the TRGB distances to published Cepheid distances, we investigate the metallicity dependence of the Cepheid period-luminosity relation. Our sample is supplemented by 10 additional galaxies for which both TRGB and Cepheid distances are available in the literature, thus providing a uniform coverage in Cepheid abundances between 1/20 and 2 (O/H)solar. We find that the difference between Cepheid and TRGB distances decreases monotonically with increasing Cepheid abundance, consistent with a mean metallicity dependence of the Cepheid distance moduli of (delta(m-M))/(delta[O/H]) = -0.24 +- 0.05 mag/dex.

  19. Estimation of stellar atmospheric parameters from SDSS/SEGUE spectra

    E-Print Network [OSTI]

    P. Re Fiorentin; C. A. L. Bailer-Jones; Y. S. Lee; T. C. Beers; T. Sivarani; R. Wilhelm; C. Allende Prieto; J. E. Norris

    2007-03-13

    We present techniques for the estimation of stellar atmospheric parameters (Teff,logg,[Fe/H]) for stars from the SDSS/SEGUE survey. The atmospheric parameters are derived from the observed medium-resolution (R=2000) stellar spectra using non-linear regression models trained either on (1) pre-classified observed data or (2) synthetic stellar spectra. In the first case we use our models to automate and generalize parametrization produced by a preliminary version of the SDSS/SEGUE Spectroscopic Parameter Pipeline (SSPP). In the second case we directly model the mapping between synthetic spectra (derived from Kurucz model atmospheres) and the atmospheric parameters, independently of any intermediate estimates. After training, we apply our models to various samples of SDSS spectra to derive atmospheric parameters, and compare our results with those obtained previously by the SSPP for the same samples. We obtain consistency between the two approaches, with RMS deviations of 150K in Teff, 0.35dex in logg, and 0.22dex in [Fe/H]. The models are applied to pre-processed spectra, either via Principal Components Analysis or a Wavelength Range Selection method, which employs a subset of the full 3850-9000A spectral range. This is both for computational reasons, and because it delivers higher accuracy. From an analysis of cluster candidates with available SDSS spectroscopy (M15, M13, M2, and NGC2420), we find evidence for small systematic offsets in Teff and/or logg for the atmospheric parameter estimates from the model trained on real data with the SSPP. Thus, this model turns out to derive more precise, but less accurate, atmospheric parameters than the model trained on synthetic data.

  20. The Chemical Enrichment History of the Large Magellanic Cloud

    E-Print Network [OSTI]

    Ricardo Carrera; Carme Gallart; Eduardo Hardy; Antonio Aparicio; Robert Zinn

    2007-10-16

    Ca II triplet spectroscopy has been used to derive stellar metallicities for individual stars in four LMC fields situated at galactocentric distances of 3\\arcdeg, 5\\arcdeg, 6\\arcdeg\\@ and 8\\arcdeg\\@ to the north of the Bar. Observed metallicity distributions show a well defined peak, with a tail toward low metallicities. The mean metallicity remains constant until 6\\arcdeg\\@ ([Fe/H]$\\sim$-0.5 dex), while for the outermost field, at 8\\arcdeg, the mean metallicity is substantially lower than in the rest of the disk ([Fe/H]$\\sim$-0.8 dex). The combination of spectroscopy with deep CCD photometry has allowed us to break the RGB age--metallicity degeneracy and compute the ages for the objects observed spectroscopically. The obtained age--metallicity relationships for our four fields are statistically indistinguishable. We conclude that the lower mean metallicity in the outermost field is a consequence of it having a lower fraction of intermediate-age stars, which are more metal-rich than the older stars. The disk age--metallicity relationship is similar to that for clusters. However, the lack of objects with ages between 3 and 10 Gyr is not observed in the field population. Finally, we used data from the literature to derive consistently the age--metallicity relationship of the bar. Simple chemical evolution models have been used to reproduce the observed age--metallicity relationships with the purpose of investigating which mechanism has participated in the evolution of the disk and bar. We find that while the disk age--metallicity relationship is well reproduced by close-box models or models with a small degree of outflow, that of the bar is only reproduced by models with combination of infall and outflow.

  1. The Carina project. VII. Toward the breaking of the age-metallicity degeneracy of red giant branch stars using the C {sub U,} {sub B,} {sub I} index

    SciTech Connect (OSTI)

    Monelli, M.; Milone, A. P.; Gallart, C.; Aparicio, A. [Instituto de Astrofísica de Canarias, Calle Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Fabrizio, M.; Cassisi, S.; Buonanno, R. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico Collurania, Via M. Maggini, I-64100 Teramo (Italy); Bono, G. [Dipartimento di Fisica, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Stetson, P. B. [Dominion Astrophysical Observatory, NRC-Herzberg, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Walker, A. R. [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile); Nonino, M. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-40131 Trieste (Italy); Dall'Ora, M. [INAF—Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); Ferraro, I.; Iannicola, G.; Pulone, L. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone, I-00044 Rome (Italy); Thévenin, F., E-mail: monelli@iac.es [Université de Nice Sophia-antipolis, CNRS, Observatoire de la Côte d'Azur, Laboratoire Lagrange, BP 4229, F-06304 Nice (France)

    2014-12-01

    We present an analysis of photometric and spectroscopic data of the Carina dSph galaxy, testing a new approach similar to that used to disentangle multiple populations in Galactic globular clusters (GCs). We show that a proper color combination is able to separate a significant fraction of the red giant branch (RGB) of the two main Carina populations (the old one, ?12 Gyr, and the intermediate-age one, 4-8 Gyr). In particular, the c {sub U,} {sub B,} {sub I} = (U – B) – (B – I) pseudo-color allows us to follow the RGB of both populations along a relevant portion of the RGB. We find that the oldest stars have a more negative c {sub U,} {sub B,} {sub I} pseudo-color than intermediate-age ones. We correlate the pseudo-color of RGB stars with their chemical properties, finding a significant trend between the iron content and the c {sub U,} {sub B,} {sub I}. Stars belonging to the old population are systematically more metal-poor ([Fe/H] =–2.32 ± 0.08 dex) than the intermediate-age ones ([Fe/H] =–1.82 ± 0.03 dex). This gives solid evidence of the chemical evolution history of this galaxy, and we have a new diagnostic that can allow us to break the age-metallicity degeneracy of H-burning advanced evolutionary phases. We compared the distribution of stars in the c {sub U,} {sub B,} {sub I} plane with theoretical isochrones, finding that no satisfactory agreement can be reached with models developed in a theoretical framework based on standard heavy element distributions. Finally, we discuss possible systematic differences when compared with multiple populations in GCs.

  2. The chemical abundances of the Ap star HD94660

    SciTech Connect (OSTI)

    Giarrusso, M. [Università di Catania, Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Via S. Sofia 78, 95123 Catania (Italy); INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania (Italy); INFN - Laboratori Nazionali del Sud (Italy)

    2014-05-09

    In this work I present the determination of chemical abundances of the Ap star HD94660, a possible rapid oscillating star. As all the magnetic chemically peculiar objects, it presents CNO underabundance and overabundance of iron peak elements of ?100 times and of rare earths up to 4 dex with respect to the Sun. The determination was based on the conversion of the observed equivalent widths into abundances simultaneously to the determination of effective temperature and gravity. Since the Balmer lines of early type stars are very sensitive to the surface gravity while the flux distribution is sensitive to the effective temperature, I have adopted an iterative procedure to match the H{sub ?} line profile and the observed UV-Vis-NIR magnitudes of HD94660 looking for a consistency between the metallicity of the atmosphere model and the derived abundances. From my spectroscopic analysis, this star belongs to the no-rapid oscillating class.

  3. A New Metallicity Calibration for Dwarfs for the RGU-Photometry

    E-Print Network [OSTI]

    S. Karaali; S. Bilir

    2003-03-20

    We adopted the procedure of Carney to obtain a metallicity calibration for dwarfs for the RGU-photometry. For this purpose we selected 76 dwarfs of different metallicities from Carney, and Strobel et al., and evaluated their \\delta(U-G) ultra-violet excess relative to Hyades by transforming their UBV magnitudes to RGU via metallicity dependent equations of Ak-Gungor. The \\delta_{0.6}/\\deltaM normalized factors of Sandage transform \\delta(U-G) excess at any G-R to \\delta=\\delta_{1.08}, i.e.: the ultra-violet excess at G-R=1.08 mag, corresponding to B-V = 0.60 mag in the UBV-system. Finally, the (\\delta, [Fe/H]) couples were fitted by the equation [Fe/H] = 0.11-2.22d-7.95d^2. This calibration covers the metallicity interval (-2.20, +0.20) dex.

  4. Lithium Depletion of Nearby Young Stellar Associations

    E-Print Network [OSTI]

    Erin Mentuch; Alexis Brandeker; Marten H. van Kerkwijk; Ray Jayawardhana; Peter H. Hauschildt

    2008-08-26

    We estimate cluster ages from lithium depletion in five pre-main-sequence groups found within 100 pc of the Sun: TW Hydrae Association, Eta Chamaeleontis Cluster, Beta Pictoris Moving Group, Tucanae-Horologium Association and AB Doradus Moving Group. We determine surface gravities, effective temperatures and lithium abundances for over 900 spectra through least squares fitting to model-atmosphere spectra. For each group, we compare the dependence of lithium abundance on temperature with isochrones from pre-main-sequence evolutionary tracks to obtain model dependent ages. We find that the Eta Chamaelontis Cluster and the TW Hydrae Association are the youngest, with ages of 12+/-6 Myr and 12+/-8 Myr, respectively, followed by the Beta Pictoris Moving Group at 21+/-9 Myr, the Tucanae-Horologium Association at 27+/-11 Myr, and the AB Doradus Moving Group at an age of at least 45 Myr (where we can only set a lower limit since the models -- unlike real stars -- do not show much lithium depletion beyond this age). Here, the ordering is robust, but the precise ages depend on our choice of both atmospheric and evolutionary models. As a result, while our ages are consistent with estimates based on Hertzsprung-Russell isochrone fitting and dynamical expansion, they are not yet more precise. Our observations do show that with improved models, much stronger constraints should be feasible: the intrinsic uncertainties, as measured from the scatter between measurements from different spectra of the same star, are very low: around 10 K in effective temperature, 0.05 dex in surface gravity, and 0.03 dex in lithium abundance.

  5. A chemical confirmation of the faint Boötes II dwarf spheroidal galaxy

    SciTech Connect (OSTI)

    Koch, Andreas [Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, D-69117 Heidelberg (Germany); Rich, R. Michael, E-mail: akoch@lsw.uni-heidelberg.de [University of California Los Angeles, Department of Physics and Astronomy, Los Angeles, CA (United States)

    2014-10-10

    We present a chemical abundance study of the brightest confirmed member star of the ultra-faint dwarf galaxy Boötes II from Keck/HIRES high-resolution spectroscopy at moderate signal-to-noise ratios. At [Fe/H] = –2.93 ± 0.03(stat.) ± 0.17(sys.), this star chemically resembles metal-poor halo field stars and the signatures of other faint dwarf spheroidal galaxies at the same metallicities in that it shows enhanced [?/Fe] ratios, Solar Fe-peak element abundances, and low upper limits on the neutron-capture element Ba. Moreover, this star shows no chemical peculiarities in any of the eight elements we were able to measure. This implies that the chemical outliers found in other systems remain outliers pertaining to the unusual enrichment histories of the respective environments, while Boo II appears to have experienced an enrichment history typical of its very low mass. We also re-calibrated previous measurements of the galaxy's metallicity from the calcium triplet (CaT) and find a much lower value than reported before. The resulting broad metallicity spread, in excess of one dex, the very metal-poor mean, and the chemical abundance patterns of the present star imply that Boötes II is a low-mass, old, metal-poor dwarf galaxy and not an overdensity associated with the Sagittarius Stream as has been previously suggested based on its sky position and kinematics. The low, mean CaT metallicity of –2.7 dex falls right on the luminosity-metallicity relation delineated over four orders of magnitude from the more luminous to the faintest galaxies. Thus Boötes II's chemical enrichment appears representative of the galaxy's original mass, while tidal stripping and other mass loss mechanisms were probably not significant as for other low-mass satellites.

  6. A NEW SYNTHETIC LIBRARY OF THE NEAR-INFRARED Ca II TRIPLET INDICES. I. INDEX DEFINITION, CALIBRATION, AND RELATIONS WITH STELLAR ATMOSPHERIC PARAMETERS

    SciTech Connect (OSTI)

    Du, W.; Luo, A. L.; Zhao, Y. H. E-mail: lal@nao.cas.cn

    2012-02-15

    Adopting the SPECTRUM package, which is a stellar spectral synthesis program, we have synthesized a comprehensive set of 2890 near-infrared (NIR) synthetic spectra with a resolution and wavelength sampling similar to the Sloan Digital Sky Survey (SDSS) and the forthcoming Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. During the synthesis, we applied the 'New grids of ATLAS9 Model Atmosphere' to develop a grid of local thermodynamic equilibrium model atmospheres for effective temperatures (T{sub eff}) ranging from 3500 to 7500 K, for surface gravities (log g) from 0.5 to 5.0 dex, for metallicities ([Fe/H]) from -4.0 to 0.5 dex, and for solar ([{alpha}/Fe] = 0.0 dex) and non-solar ([{alpha}/Fe] = +0.4 dex) abundances. This synthetic stellar library is composed of 1350 solar scaled abundance (SSA) and 1530 non-solar scaled abundance (NSSA) spectra, grounding on which we have defined a new set of NIR Ca II triplet indices and an index CaT as the sum of the three. These defined indices were automatically measured on every spectrum of the synthetic stellar library and calibrated with the indices computed on the observational spectra from the INDO-U.S. stellar library. In order to check the effect of {alpha}-element enhancement on the so-defined Ca II indices, we compared indices measured on the SSA spectra with those on the NSSA ones at the same trine of stellar parameters (T{sub eff}, log g, [Fe/H]); luckily, little influences of {alpha}-element enhancement were found. Furthermore, comparisons of our synthetic indices with the observational ones from measurements on the INDO-U.S. stellar library, the SDSS-DR7 and SDSS-DR8 spectroscopic survey are presented, respectively, for dwarfs and giants in specific. For dwarfs, our synthetic indices could well reproduce the behaviors of the observational indices versus stellar parameters, which verifies the validity of our index definitions for dwarfs. For giants, the consistency between our synthetic indices and the observational ones does not appear to be as good. However, a new synthetic library of NIR Ca II indices has been founded for deeper studies on the NIR wave band of stellar spectra, and this library is particularly appropriate for the SDSS and the forthcoming LAMOST stellar spectra. We have regressed the strength of the CaT index as a function of stellar parameters for both dwarfs and giants after a series of experimental investigations into relations of the indices with stellar parameters. For dwarfs, log g has little effect on the indices, while [Fe/H] and T{sub eff} play a role together. The leading factor is probably [Fe/H], which changes the strength of the indices by a positive trend. For giants, log g starts to influence the strength of the indices by a negative trend for the metal-poor, and even impact deeply for the metal-rich; besides, [Fe/H] and T{sub eff} still matter. In addition, we briefly discussed the major differences between our Ca II triplet indices and the CaHK doublet indices. Ultimately, a supplemental experiment was carried out to show that spectral noises do have effects on our set of NIR Ca II indices. However, the influence is not weak enough to be ignored if the signal-to-noise ratio falls below 20.

  7. The Milky Way Tomography with SDSS: II. Stellar Metallicity

    E-Print Network [OSTI]

    Zeljko Ivezic; Branimir Sesar; Mario Juric; Nicholas Bond; Julianne Dalcanton; Constance M. Rockosi; Brian Yanny; Heidi J. Newberg; Timothy C. Beers; Carlos Allende Prieto; Ron Wilhelm; Young Sun Lee; Thirupathi Sivarani; John E. Norris; Coryn A. L. Bailer-Jones; Paola Re Fiorentin; David Schlegel; Alan Uomoto; Robert H. Lupton; Gillian R. Knapp; James E. Gunn; Kevin R. Covey; J. Allyn Smith; Gajus Miknaitis; Mamoru Doi; Masayuki Tanaka; Masataka Fukugita; Steve Kent; Douglas Finkbeiner; Jeffrey A. Munn; Jeffrey R. Pier; Tom Quinn; Suzanne Hawley; Scott Anderson; Furea Kiuchi; Alex Chen; James Bushong; Harkirat Sohi; Daryl Haggard; Amy Kimball; John Barentine; Howard Brewington; Mike Harvanek; Scott Kleinman; Jurek Krzesinski; Dan Long; Atsuko Nitta; Stephanie Snedden; Brian Lee; Hugh Harris; Jonathan Brinkmann; Donald P. Schneider; Donald G. York

    2008-04-24

    Using effective temperature and metallicity derived from SDSS spectra for ~60,000 F and G type main sequence stars (0.2in a conflict with the traditional decomposition in terms of thin and thick disks. We detect coherent substructures in the kinematics--metallicity space, such as the Monoceros stream, which rotates faster than the LSR, and has a median metallicity of [Fe/H]=-0.96, with an rms scatter of only ~0.15 dex. We extrapolate our results to the performance expected from the Large Synoptic Survey Telescope (LSST) and estimate that the LSST will obtain metallicity measurements accurate to 0.2 dex or better, with proper motion measurements accurate to ~0.2 mas/yr, for about 200 million F/G dwarf stars within a distance limit of ~100 kpc (g<23.5). [abridged

  8. HIGH PRECISION ABUNDANCES OF THE OLD SOLAR TWIN HIP 102152: INSIGHTS ON Li DEPLETION FROM THE OLDEST SUN

    SciTech Connect (OSTI)

    Monroe, TalaWanda R.; Melendez, Jorge; Tucci Maia, Marcelo; Freitas, Fabricio C.; Yong, David; Asplund, Martin; Alves-Brito, Alan; Casagrande, Luca; Bergemann, Maria; Bedell, Megan; Bean, Jacob; Lind, Karin; Castro, Matthieu; Do Nascimento, Jose-Dias; Bazot, Michael

    2013-09-10

    We present the first detailed chemical abundance analysis of the old 8.2 Gyr solar twin, HIP 102152. We derive differential abundances of 21 elements relative to the Sun with precisions as high as 0.004 dex ({approx}<1%), using ultra high-resolution (R = 110,000), high S/N UVES spectra obtained on the 8.2 m Very Large Telescope. Our determined metallicity of HIP 102152 is [Fe/H] = -0.013 {+-} 0.004. The atmospheric parameters of the star were determined to be 54 K cooler than the Sun, 0.09 dex lower in surface gravity, and a microturbulence identical to our derived solar value. Elemental abundance ratios examined versus dust condensation temperature reveal a solar abundance pattern for this star, in contrast to most solar twins. The abundance pattern of HIP 102152 appears to be the most similar to solar of any known solar twin. Abundances of the younger, 2.9 Gyr solar twin, 18 Sco, were also determined from UVES spectra to serve as a comparison for HIP 102152. The solar chemical pattern of HIP 102152 makes it a potential candidate to host terrestrial planets, which is reinforced by the lack of giant planets in its terrestrial planet region. The following non-local thermodynamic equilibrium Li abundances were obtained for HIP 102152, 18 Sco, and the Sun: log {epsilon} (Li) = 0.48 {+-} 0.07, 1.62 {+-} 0.02, and 1.07 {+-} 0.02, respectively. The Li abundance of HIP 102152 is the lowest reported to date for a solar twin, and allows us to consider an emerging, tightly constrained Li-age trend for solar twin stars.

  9. A NEW CEPHEID DISTANCE TO THE GIANT SPIRAL M101 BASED ON IMAGE SUBTRACTION OF HUBBLE SPACE TELESCOPE/ADVANCED CAMERA FOR SURVEYS OBSERVATIONS

    SciTech Connect (OSTI)

    Shappee, Benjamin J.; Stanek, K. Z. E-mail: kstanek@astronomy.ohio-state.edu

    2011-06-01

    We accurately determine a new Cepheid distance to M101 (NGC 5457) using archival Hubble Space Telescope (HST)/Advanced Camera for Surveys V and I time series photometry of two fields within the galaxy. We make a slight modification to the ISIS image subtraction package to obtain optimal differential light curves from HST data. We discovered 827 Cepheids with periods between 3 and 80 days, the largest extragalactic sample of Cepheids observed with HST by a factor of two. With this large Cepheid sample, we find that the relative distance of M101 from the Large Magellanic Cloud is {Delta}{mu}{sub LMC} = 10.63 {+-} 0.04 (random) {+-} 0.06 (systematic) mag. If we use the geometrically determined maser distance to NGC 4258 as our distance anchor, the distance modulus of M101 is {mu}{sub 0} = 29.04 {+-} 0.05 (random) {+-} 0.18 (systematic) mag or D = 6.4 {+-} 0.2 (random) {+-} 0.5 (systematic) Mpc. The uncertainty is dominated by the maser distance estimate ({+-}0.15 mag), which should improve over the next few years. We determine a steep metallicity dependence, {gamma}, for our Cepheid sample through two methods, yielding {gamma} = -0.80 {+-} 0.21 (random) {+-} 0.06 (systematic) mag dex{sup -1} and {gamma} = -0.72{sup +0.22}{sub -0.25} (random) {+-} 0.06 (systematic) mag dex{sup -1}. We see marginal evidence for variations in the Wesenheit period-luminosity relation slope as a function of deprojected galactocentric radius. We also use the tip of the red giant branch method to independently determine the distance modulus to M101 of {mu}{sub 0} = 29.05 {+-} 0.06 (random) {+-} 0.12 (systematic) mag.

  10. Descriptive logs, skeletonized samples, and photographs of core...

    Open Energy Info (EERE)

    dex.php?titleDescriptivelogs,skeletonizedsamples,andphotographsofcorefromPrescoEnergy%27sthermalgradientwellsP3-1,P10-1,andP32-2intheRyePatcharea,PershingC...

  11. Inhibition of extracellular protease secretion by Aspergillus niger using cell

    E-Print Network [OSTI]

    Gu, Tingyue

    , Forma Scientific Inc.) The spores were harvested by adding 20 mL of sterilized distilled water composition (g/L): 3 yeast extract, 3 malt extract, 5 peptone, and 10 dex- trose. Culture conditions Shake

  12. Brr2 RNA helicase and its protein and RNA interactions 

    E-Print Network [OSTI]

    Hahn, Daniela

    2011-11-24

    The dynamic rearrangements of RNA and protein complexes and the fidelity of pre-mRNA splicing are governed by DExD/H-box ATPases. One of the spliceosomal ATPases, Brr2, is believed to facilitate conformational rearrangements ...

  13. Type-Ia Supernova Remnant Shell At $Z=3.5$ Seen In The Three Sightlines Toward The Gravitationally Lensed Qso B1422+231

    E-Print Network [OSTI]

    Hamano, Satoshi; Kondo, Sohei; Tsujimoto, Takuji; Okoshi, Katsuya; Shigeyama, Toshikazu

    2012-01-01

    Using the Subaru 8.2m Telescope with an IRCS Echelle spectrograph, we obtained high-resolution (R=10,000) near-infrared (1.01-1.38 \\mu m) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z=3.628) consisting of four known lensed images. We detected MgII absorption lines at z=3.54, which show a large variance of column densities (~ 0.3 dex) and velocities (~ 10 km/s) between the sightlines A and B with a projected separation of only 8.4h_{70}^{-1} pc at the redshift. This is the smallest spatial structure of the high-z gas clouds ever detected after Rauch et al. found a 20-pc scale structure for the same z=3.54 absorption system using optical spectra of images A and C. The observed systematic variances imply that the system is an expanding shell as originally suggested by Rauch et al. By combining the data for three sightlines, we managed to constrain the radius and expansion velocity of the shell (~ 50-100 pc, 130 km/s), concluding that the shell is truly a supernova remnant (SNR) rather ...

  14. COSMIC ORIGINS SPECTROGRAPH OBSERVATIONS OF WARM INTERVENING GAS AT z {approx} 0.325 TOWARD 3C 263

    SciTech Connect (OSTI)

    Narayanan, Anand [Indian Institute of Space Science and Technology, Thiruvananthapuram 695547, Kerala (India); Savage, Blair D.; Wakker, Bart P., E-mail: anand@iist.ac.in, E-mail: savage@astro.wisc.edu, E-mail: wakker@astro.wisc.edu [Department of Astronomy, University of Wisconsin-Madison, 5534 Sterling Hall, 475 N. Charter Street, Madison, WI 53706-1582 (United States)

    2012-06-10

    We present HST/COS high-S/N observations of the z = 0.32566 multiphase absorber toward 3C 263. The Cosmic Origins Spectrograph (COS) data show absorption from H I (Ly{alpha} to Ly{theta}), O VI, C III, N III, Si III, and C II. The Ne VIII in this absorber is detected in the FUSE spectrum along with O III, O IV, and N IV. The low and intermediate ions are kinematically aligned with each other and H I and display narrow line widths of b {approx} 6-8 km s{sup -1}. The O VI {lambda}{lambda}1031, 1037 lines are kinematically offset by {Delta}v {approx} 12 km s{sup -1} from the low ions and are a factor of {approx}4 broader. All metal ions except O VI and Ne VIII are consistent with an origin in gas photoionized by the extragalactic background radiation. The bulk of the observed H I is also traced by this photoionized medium. The metallicity in this gas phase is Z {approx}> 0.15 Z{sub Sun} with carbon having near-solar abundances. The O VI and Ne VIII favor an origin in collisionally ionized gas at T = 5.2 Multiplication-Sign 10{sup 5} K. The H I absorption associated with this warm absorber is a broad-Ly{alpha} absorber (BLA) marginally detected in the COS spectrum. This warm gas phase has a metallicity of [X/H] {approx}-0.12 dex, and a total hydrogen column density of N( H) {approx} 3 Multiplication-Sign 10{sup 19} cm{sup -2}, which is {approx}2 dex higher than what is traced by the photoionized gas. Simultaneous detection of O VI, Ne VIII, and BLAs in an absorber can be a strong diagnostic of gas with T {approx} 10{sup 5}-10{sup 6} K corresponding to the warm phase of the warm-hot intergalactic medium or shock-heated gas in the extended halos of galaxies.

  15. COSMIC EVOLUTION OF BLACK HOLES AND SPHEROIDS. IV. THE M{sub BH}-L{sub sph} RELATION

    SciTech Connect (OSTI)

    Bennert, Vardha Nicola; Treu, Tommaso; Le Bris, Alexandre; Auger, Matthew W. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Woo, Jong-Hak; Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Gallagher, Sarah [Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7 (Canada); Blandford, Roger D., E-mail: bennert@physics.ucsb.ed, E-mail: tt@physics.ucsb.ed, E-mail: mauger@physics.ucsb.ed, E-mail: woo@astro.ucla.ed, E-mail: malkan@astro.ucla.ed, E-mail: alexandrelebris@gmail.co, E-mail: sgalla4@uwo.c, E-mail: rdb@slac.stanford.ed [Kavli Institute for Particle Astrophysics and Cosmology, Stanford, CA 94305 (United States)

    2010-01-10

    From high-resolution images of 23 Seyfert-1 galaxies at z = 0.36 and z = 0.57 obtained with the Near-Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope (HST), we determine host-galaxy morphology, nuclear luminosity, total host-galaxy luminosity, and spheroid luminosity. Keck spectroscopy is used to estimate black hole mass (M{sub BH}). We study the cosmic evolution of the M{sub BH}-spheroid luminosity (L{sub sph}) relation. In combination with our previous work, totaling 40 Seyfert-1 galaxies, the covered range in BH mass is substantially increased, allowing us to determine for the first time intrinsic scatter and correct evolutionary trends for selection effects. We re-analyze archival HST images of 19 local reverberation-mapped active galaxies to match the procedure adopted at intermediate redshift. Correcting spheroid luminosity for passive luminosity evolution and taking into account selection effects, we determine that at fixed present-day V-band spheroid luminosity, M{sub BH}/L{sub sph} propor to(1 + z){sup 2.8+}-{sup 1.2}. When including a sample of 44 quasars out to z = 4.5 taken from the literature, with luminosity and BH mass corrected to a self-consistent calibration, we extend the BH mass range to over 2 orders of magnitude, resulting in M{sub BH}/L{sub sph} propor to(1 + z){sup 1.4+}-{sup 0.2}. The intrinsic scatter of the relation, assumed constant with redshift, is 0.3 +- 0.1 dex (<0.6 dex at 95% CL). The evolutionary trend suggests that BH growth precedes spheroid assembly. Interestingly, the M{sub BH}-total-host-galaxy-luminosity relation is apparently non-evolving. It hints at either a more fundamental relation or that the spheroid grows by a redistribution of stars. However, the high-z sample does not follow this relation, indicating that major mergers may play the dominant role in growing spheroids above z approx = 1.

  16. KILOPARSEC-SCALE PROPERTIES OF EMISSION-LINE GALAXIES

    SciTech Connect (OSTI)

    Hemmati, Shoubaneh; Miller, Sarah H.; Mobasher, Bahram; Nayyeri, Hooshang; Ferguson, Henry C.; Koekemoer, Anton M.; Guo, Yicheng; Koo, David C.

    2014-12-20

    We perform a detailed study of the resolved properties of emission-line galaxies at kiloparsec scales to investigate how small-scale and global properties of galaxies are related. We use a sample of 119 galaxies in the GOODS fields. The galaxies are selected to cover a wide range in morphologies over the redshift range 0.2 < z < 1.3. High resolution spectroscopic data from Keck/DEIMOS observations are used to fix the redshift of all the galaxies in our sample. Using the HST/ACS and HST/WFC3 imaging data taken as a part of the CANDELS project, for each galaxy, we perform spectral energy distribution fitting per resolution element, producing resolved rest-frame U – V color, stellar mass, star formation rate (SFR), age, and extinction maps. We develop a technique to identify ''regions'' of statistical significance within individual galaxies, using their rest-frame color maps to select red and blue regions, a broader definition for what are called ''clumps'' in other works. As expected, for any given galaxy, the red regions are found to have higher stellar mass surface densities and older ages compared to the blue regions. Furthermore, we quantify the spatial distribution of red and blue regions with respect to both redshift and stellar mass, finding that the stronger concentration of red regions toward the centers of galaxies is not a significant function of either redshift or stellar mass. We find that the ''main sequence'' of star-forming galaxies exists among both red and blue regions inside galaxies, with the median of blue regions forming a tighter relation with a slope of 1.1 ± 0.1 and a scatter of ?0.2 dex compared to red regions with a slope of 1.3 ± 0.1 and a scatter of ?0.6 dex. The blue regions show higher specific SFRs (sSFRs) than their red counterparts with the sSFR decreasing since z ? 1, driven primarily by the stellar mass surface densities rather than the SFRs at a given resolution element.

  17. M dwarf metallicities and giant planet occurrence: Ironing out uncertainties and systematics

    SciTech Connect (OSTI)

    Gaidos, Eric; Mann, Andrew W.

    2014-08-10

    Comparisons between the planet populations around solar-type stars and those orbiting M dwarfs shed light on the possible dependence of planet formation and evolution on stellar mass. However, such analyses must control for other factors, i.e., metallicity, a stellar parameter that strongly influences the occurrence of gas giant planets. We obtained infrared spectra of 121 M dwarfs stars monitored by the California Planet Search and determined metallicities with an accuracy of 0.08 dex. The mean and standard deviation of the sample are –0.05 and 0.20 dex, respectively. We parameterized the metallicity dependence of the occurrence of giant planets on orbits with a period less than two years around solar-type stars and applied this to our M dwarf sample to estimate the expected number of giant planets. The number of detected planets (3) is lower than the predicted number (6.4), but the difference is not very significant (12% probability of finding as many or fewer planets). The three M dwarf planet hosts are not especially metal rich and the most likely value of the power-law index relating planet occurrence to metallicity is 1.06 dex per dex for M dwarfs compared to 1.80 for solar-type stars; this difference, however, is comparable to uncertainties. Giant planet occurrence around both types of stars allows, but does not necessarily require, a mass dependence of ?1 dex per dex. The actual planet-mass-metallicity relation may be complex, and elucidating it will require larger surveys like those to be conducted by ground-based infrared spectrographs and the Gaia space astrometry mission.

  18. The COS/UVES Absorption Survey of the Magellanic Stream: II. Evidence for a complex enrichment history of the Stream from the Fairall 9 sightline

    E-Print Network [OSTI]

    Richter, Philipp; Wakker, Bart P; Lehner, Nicolas; Howk, J Christopher; Bland-Hawthorn, Joss; Bekhti, Nadya Ben; Fechner, Cora

    2013-01-01

    We present a multi-wavelength study of the Magellanic Stream (MS), a massive gaseous structure in the Local Group that is believed to represent material stripped from the Magellanic Clouds. We use ultraviolet, optical and radio data obtained with HST/COS, VLT/UVES, FUSE and GASS to study metal abundances and physical conditions in the Stream toward the quasar Fairall 9. Line absorption in the MS is detected from a large number of metal ions and from molecular hydrogen. From the analysis of unsaturated SII absorption, in combination with a detailed photoionization model, we obtain a surprisingly high alpha abundance in the Stream toward Fairall 9 of [S/H]=-0.30pm0.04 (0.5 solar). This value is 5 times higher than what is found along other MS sightlines based on similar COS/UVES data sets. In contrast, the measured nitrogen abundance is found to be substantially lower ([N/H]=-1.15pm0.06), implying a very low [alpha/N] ratio of -0.85 dex. The substantial differences in the chemical composition of the Magellanic ...

  19. On the deduction of galaxy abundances with evolutionary neural networks

    E-Print Network [OSTI]

    Michael Taylor; Angeles I. Diaz

    2007-09-19

    A growing number of indicators are now being used with some confidence to measure the metallicity(Z) of photoionisation regions in planetary nebulae, galactic HII regions(GHIIRs), extra-galactic HII regions(EGHIIRs) and HII galaxies(HIIGs). However, a universal indicator valid also at high metallicities has yet to be found. Here, we report on a new artificial intelligence-based approach to determine metallicity indicators that shows promise for the provision of improved empirical fits. The method hinges on the application of an evolutionary neural network to observational emission line data. The network's DNA, encoded in its architecture, weights and neuron transfer functions, is evolved using a genetic algorithm. Furthermore, selection, operating on a set of 10 distinct neuron transfer functions, means that the empirical relation encoded in the network solution architecture is in functional rather than numerical form. Thus the network solutions provide an equation for the metallicity in terms of line ratios without a priori assumptions. Tapping into the mathematical power offered by this approach, we applied the network to detailed observations of both nebula and auroral emission lines in the optical for a sample of 96 HII-type regions and we were able to obtain an empirical relation between Z and S23 with a dispersion of only 0.16 dex. We show how the method can be used to identify new diagnostics as well as the nonlinear relationship supposed to exist between the metallicity Z, ionisation parameter U and effective (or equivalent) temperature T*.

  20. Hunting the parent of the Orphan stream. II. The first high-resolution spectroscopic study

    SciTech Connect (OSTI)

    Casey, Andrew R.; Keller, Stefan C.; Da Costa, Gary; Maunder, Elizabeth [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Frebel, Anna, E-mail: andrew.casey@anu.edu.au [Department of Physics, Massachusetts Institute of Technology and Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States)

    2014-03-20

    We present the first high-resolution spectroscopic study on the Orphan stream for five stream candidates, observed with the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Clay telescope. The targets were selected from the low-resolution catalog of Casey et al.: three high-probability members, one medium, and one low-probability stream candidate were observed. Our analysis indicates that the low- and medium-probability targets are metal-rich field stars. The remaining three high-probability targets range over ?1 dex in metallicity, and are chemically distinct compared to the other two targets and all standard stars: low [?/Fe] abundance ratios are observed, and lower limits are ascertained for [Ba/Y], which sit well above the Milky Way trend. These chemical signatures demonstrate that the undiscovered parent system is unequivocally a dwarf spheroidal galaxy, consistent with dynamical constraints inferred from the stream width and arc. As such, we firmly exclude the proposed association between NGC 2419 and the Orphan stream. A wide range in metallicities adds to the similarities between the Orphan stream and Segue 1, although the low [?/Fe] abundance ratios in the Orphan stream are in tension with the high [?/Fe] values observed in Segue 1. Open questions remain before Segue 1 could possibly be claimed as the 'parent' of the Orphan stream. The parent system could well remain undiscovered in the southern sky.

  1. NGC 6139: a normal massive globular cluster or a first-generation dominated cluster? Clues from the light elements

    E-Print Network [OSTI]

    Bragaglia, A; Sollima, A; Donati, P; D'Orazi, V; Gratton, R G; Lucatello, S; Sneden, C

    2015-01-01

    Information on globular clusters (GC) formation mechanisms can be gathered by studying the chemical signature of the multiple populations that compose these stellar systems. In particular, we are investigating the anticorrelations among O, Na, Al, and Mg to explore the influence of cluster mass and environment on GCs in the Milky Way and in extragalactic systems. We present here the results obtained on NGC 6139 which, on the basis of its horizontal branch morphology, had been proposed to be dominated by first-generation stars. In our extensive study based on high resolution spectroscopy, the first for this cluster, we found a metallicity of [Fe/H]= -1.579 +/- 0.015 +/- 0.058 (rms=0.040 dex, 45 bona fide member stars) on the UVES scale defined by our group. The stars in NGC 6139 show a chemical pattern normal for GCs, with a rather extended Na-O (and Mg-Al) anticorrelation. NGC 6139 behaves like expected from its mass and contains a large fraction (about two thirds) of second-generation stars.

  2. Ground-based observations of the beta Cephei CoRoT main target HD 180642: abundance analysis and mode identification

    E-Print Network [OSTI]

    Briquet, M; Morel, T; Aerts, C; De Cat, P; Mathias, P; Lefever, K; Miglio, A; Poretti, E; Martin-Ruiz, S; Paparo, M; Rainer, M; Carrier, F; Gutiérrez-Soto, J; Valtier, J C; Benko, J M; Bognár, Z; Niemczura, E; Amado, P J; Suárez, J C; Moya, A; Rodriguez-Lopez, C; Garrido, R

    2009-01-01

    The known beta Cephei star HD 180642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote and collaborators). In this paper, we obtain additional constraints for forthcoming asteroseismic modeling of the target. Our results are based on both extensive ground-based multicolour photometry and high-resolution spectroscopy. We determine T_eff = 24 500+-1000 K and log g = 3.45+-0.15 dex from spectroscopy. The derived chemical abundances are consistent with those for B stars in the solar neighbourhood, except for a mild nitrogen excess. A metallicity Z = 0.0099+-0.0016 is obtained. Three modes are detected in photometry. The degree l is unambiguously identified for two of them: l = 0 and l = 3 for the frequencies 5.48694 1/d and 0.30818 1/d, respectively. The radial mode is non-linear and highly dominant with an amplitude in the U-filter about 15 times larger than the strongest of the other modes. For th...

  3. Pipe3D, a pipeline to analyze Integral Field Spectroscopy data: I. New fitting phylosophy of FIT3D

    E-Print Network [OSTI]

    Sánchez, S F; Sánchez-Blázquez, P; González, J J; Rosález-Ortega, F F; Cano-Díaz, M; López-Cobá, C; Marino, R A; de Paz, A Gil; Mollá, M; López-Sánchez, A R; Ascasibar, Y; Barrera-Ballesteros, J

    2015-01-01

    We present an improved version of FIT3D, a fitting tool for the analysis of the spectroscopic properties of the stellar populations and the ionized gas derived from moderate resolution spectra of galaxies. FIT3D is a tool developed to analyze Integral Field Spectroscopy data and it is the basis of Pipe3D, a pipeline already used in the analysis of datasets like CALIFA, MaNGA, and SAMI. We describe the philosophy behind the fitting procedure, and in detail each of the different steps in the analysis. We present an extensive set of simulations in order to estimate the precision and accuracy of the derived parameters for the stellar populations. In summary, we find that using different stellar population templates we reproduce the mean properties of the stellar population (age, metallicity, and dust attenuation) within ~0.1 dex. A similar approach is adopted for the ionized gas, where a set of simulated emission- line systems was created. Finally, we compare the results of the analysis using FIT3D with those pro...

  4. Stellar metallicity of the extended disk and distance of the spiral galaxy NGC 3621

    SciTech Connect (OSTI)

    Kudritzki, Rolf-Peter; Bresolin, Fabio; Hosek, Matthew W. Jr.; Urbaneja, Miguel A.; Przybilla, Norbert E-mail: bresolin@ifa.hawaii.edu E-mail: Miguel.Urbaneja-Perez@uibk.ac.at

    2014-06-10

    Low resolution (?4.5 Å) ESO VLT/FORS spectra of blue supergiant stars are analyzed to determine stellar metallicities (based on elements such as iron, titanium, and magnesium) in the extended disk of the spiral galaxy, NGC 3621. Mildly subsolar metallicity (–0.30 dex) is found for the outer objects beyond 7 kpc, independent of galactocentric radius and compatible with the absence of a metallicity gradient, confirming the results of a recent investigation of interstellar medium H II region gas oxygen abundances. The stellar metallicities are slightly higher than those from the H II regions when based on measurements of the weak forbidden auroral oxygen line at 4363 Å but lower than the ones obtained with the R {sub 23} strong line method. It is shown that the present level of metallicity in the extended disk cannot be the result of chemical evolution over the age of the disk with the present rate of in situ star formation. Additional mechanisms must be involved. In addition to metallicity, stellar effective temperatures, gravities, interstellar reddening, and bolometric magnitudes are determined. After the application of individual reddening corrections for each target, the flux-weighted gravity-luminosity relationship of blue supergiant stars is used to obtain a distance modulus of 29.07 ± 0.09 mag (distance D = 6.52 ± 0.28 Mpc). This new distance is discussed in relation to Cepheid and the tip of the red giant branch distances.

  5. An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting

    E-Print Network [OSTI]

    M. Briquet; T. Morel; A. Thoul; R. Scuflaire; A. Miglio; J. Montalban; M. -A. Dupret; C. Aerts

    2007-06-22

    We present a seismic study of the beta Cephei star theta Ophiuchi. Our analysis is based on the observation of one radial mode, one rotationally split l = 1 triplet and three components of a rotationally split l = 2 quintuplet for which the m-values were well identified by spectroscopy. We identify the radial mode as fundamental, the triplet as p_1 and the quintuplet as g_1. Our NLTE abundance analysis results in a metallicity and CNO abundances in full agreement with the most recent updated solar values. With X \\in [0.71,0.7211] and Z \\in [0.009,0.015], and using the Asplund et al. (2005) mixture but with a Ne abundance about 0.3 dex larger (Cunha et al. 2006), the matching of the three independent modes, enables us to deduce constrained ranges for the mass (M = 8.2 +/- 0.3 Msun) and central hydrogen abundance (X_c = 0.38 +/- 0.02) of theta Oph and to prove the occurrence of core overshooting (alpha_ov = 0.44 +/- 0.07). We also derive an equatorial rotation velocity of 29 +/- 7 km/s. Moreover, we show that the observed non-equidistance of the l=1 triplet can be reproduced by second order effects of rotation. Finally, we show that the observed rotational splitting of two modes cannot rule out a rigid rotation model.

  6. An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting

    E-Print Network [OSTI]

    Briquet, M; Thoul, A; Scuflaire, R; Miglio, A; Montalban, J; Dupret, M -A; Aerts, C

    2007-01-01

    We present a seismic study of the beta Cephei star theta Ophiuchi. Our analysis is based on the observation of one radial mode, one rotationally split l = 1 triplet and three components of a rotationally split l = 2 quintuplet for which the m-values were well identified by spectroscopy. We identify the radial mode as fundamental, the triplet as p_1 and the quintuplet as g_1. Our NLTE abundance analysis results in a metallicity and CNO abundances in full agreement with the most recent updated solar values. With X \\in [0.71,0.7211] and Z \\in [0.009,0.015], and using the Asplund et al. (2005) mixture but with a Ne abundance about 0.3 dex larger (Cunha et al. 2006), the matching of the three independent modes, enables us to deduce constrained ranges for the mass (M = 8.2 +/- 0.3 Msun) and central hydrogen abundance (X_c = 0.38 +/- 0.02) of theta Oph and to prove the occurrence of core overshooting (alpha_ov = 0.44 +/- 0.07). We also derive an equatorial rotation velocity of 29 +/- 7 km/s. Moreover, we show that t...

  7. RECALIBRATION OF THE VIRIAL FACTOR AND M{sub BH}-{sigma}{sub *} RELATION FOR LOCAL ACTIVE GALAXIES

    SciTech Connect (OSTI)

    Park, Daeseong; Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Kelly, Brandon C.; Treu, Tommaso, E-mail: pds2001@astro.snu.ac.kr, E-mail: woo@astro.snu.ac.kr, E-mail: bckelly@physics.ucsb.edu, E-mail: tt@physics.ucsb.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

    2012-11-15

    Determining the virial factor of the broad-line region gas is crucial for calibrating active galactic nucleus black hole mass estimators, since the measured line-of-sight velocity needs to be converted into the intrinsic virial velocity. The average virial factor has been empirically calibrated based on the M{sub BH}-{sigma}{sub *} relation of quiescent galaxies, but the claimed values differ by a factor of two in recent studies. We investigate the origin of the difference by measuring the M{sub BH}-{sigma}{sub *} relation using an updated galaxy sample from the literature and explore the dependence of the virial factor on various fitting methods. We find that the discrepancy is primarily caused by the sample selection, while the difference stemming from the various regression methods is marginal. However, we generally prefer the FITEXY and Bayesian estimators based on Monte Carlo simulations for the M{sub BH}-{sigma}{sub *} relation. In addition, the choice of independent variable in the regression leads to {approx}0.2 dex variation in the virial factor inferred from the calibration process. Based on the determined virial factor, we present the updated M{sub BH}-{sigma}{sub *} relation of local active galaxies.

  8. AN H-BAND SPECTROSCOPIC METALLICITY CALIBRATION FOR M DWARFS

    SciTech Connect (OSTI)

    Terrien, Ryan C.; Mahadevan, Suvrath; Bender, Chad F.; Deshpande, Rohit; Ramsey, Lawrence W.; Bochanski, John J., E-mail: rct151@psu.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

    2012-03-10

    We present an empirical near-infrared (NIR) spectroscopic method for estimating M dwarf metallicities, based on features in the H band, as well as an implementation of a similar published method in the K band. We obtained R {approx} 2000 NIR spectra of a sample of M dwarfs using the NASA IRTF-SpeX spectrograph, including 22 M dwarf metallicity calibration targets that have FGK companions with known metallicities. The H-band and K-band calibrations provide equivalent fits to the metallicities of these binaries, with an accuracy of {+-}0.12 dex. We derive the first empirically calibrated spectroscopic metallicity estimate for the giant planet-hosting M dwarf GJ 317, confirming its supersolar metallicity. Combining this result with observations of eight other M dwarf planet hosts, we find that M dwarfs with giant planets are preferentially metal-rich compared to those that host less massive planets. Our H-band calibration relies on strongly metallicity-dependent features in the H band, which will be useful in compositional studies using mid- to high-resolution NIR M dwarf spectra, such as those produced by multiplexed surveys like SDSS-III APOGEE. These results will also be immediately useful for ongoing spectroscopic surveys of M dwarfs.

  9. Database of Geneva stellar evolution tracks and isochrones for UBVRIJHKLL'M, HST-WFPC2, Geneva and Washington photometric systems

    E-Print Network [OSTI]

    Thibault Lejeune; Daniel Schaerer

    2000-11-27

    We have used an updated version of the empirically and semi-empirically calibrated BaSeL library of synthetic stellar spectra of Lejeune et al. (1997, 1998) and Westera et al. (1999) to calculate synthetic photometry in the UBVRIJHKLL'M, HST-WFPC2, Geneva, and Washington systems for the entire set of non-rotating Geneva stellar evolution models covering masses from 0.4-0.8 to 120-150 Msun and metallicities Z=0.0004 (1/50 Zsun) to 0.1 (5 Zsun). The results are provided in a database which includes all individual stellar tracks and the corresponding isochrones covering ages from 10^3 yr to 16--20 Gyr in time steps of Delta(log t)= 0.05 dex. The database also includes a new grid of stellar tracks of very metal-poor stars (Z=0.0004) from 0.8 - 150 Msun calculated with the Geneva stellar evolution code. The full database will be available in electronic form at the CDS (http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/(vol)/(page)) and at http://webast.ast.obs-mip.fr/stellar/.

  10. The Cosmic Evolution of Metallicity from the SDSS Fossil Record

    E-Print Network [OSTI]

    Benjamin Panter; Raul Jimenez; Alan F. Heavens; Stephane Charlot

    2008-04-18

    We present the time evolution of the stellar metallicity for SDSS galaxies, a sample that spans five orders of magnitude in stellar mass (10^7 - 10^{12} Msun). Assuming the BC03 stellar population models, we find that more massive galaxies are more metal-rich than less massive ones at all redshifts; the mass-metallicity relation is imprinted in galaxies from the epoch of formation. For galaxies with present stellar masses > 10^{10} Msun, the time evolution of stellar metallicity is very weak, with at most 0.2-0.3 dex over a Hubble time- for this reason the mass-metallicity relation evolves little with redshift. However, for galaxies with present stellar masses < 10^{10} Msun, the evolution is significant, with metallicity increasing by more than a decade from redshift 3 to the present. By being able to recover the metallicity history, we have managed to identify the origin of a recent discrepancy between the metallicity recovered from nebular lines and absorption lines. As expected, we show that the young population dominates the former while the old population the latter. We have investigated the dependence on the stellar models used and find that older stellar population synthesis codes do not produce a clear result. Finally, we have explored the relationship between cluster environment and metallicity, and find a strong correlation in the sense that galaxies in high density regions have high metallicity.

  11. Luminosity-metallicity relation for stars on the lower main sequence

    E-Print Network [OSTI]

    Eira Kotoneva; Chris Flynn; Raul Jimenez

    2002-03-07

    We present a comparison of the predictions of stellar models with the luminosity of the lower main sequence ($5.5 < M_V < 7.3$) using K dwarfs in the Hipparcos catalog. The parallaxes of our comparison stars are known to better than 15% and metallicities have been recently determined from photometry. A major advantage of our comparison is that distances in our sample are known with good accuracy, while tests that involve open and globular clusters are constrained by potentially inaccurate distances. We show that the luminosity of the lower main sequence relative to a fiducial (solar metallicity) isochrone is a simple function of metallicity: $\\Delta M_V = 0.84375 \\times {\\rm [ Fe/H]} - 0.04577$. We compare the data with a range of isochrones from the literature. None of the models fit all the data, although some models do clearly better than others. In particular, metal rich isochrones seem to be difficult to construct. The relationship between luminosity, colour and metallicity for K dwarfs is found to be very tight. We are thus able to derive metallicities for K dwarfs based on their position in the Hipparcos colour-magnitude diagram with accuracies better than 0.1 dex. The metallicity-luminosity relation for K dwarfs leads to a new distance indicator with a wide range of possible applications.

  12. IONIZING RADIATION FROM z = 4-10 GALAXIES

    SciTech Connect (OSTI)

    Razoumov, Alexei O. [Institute for Computational Astrophysics, Department of Astronomy and Physics, Saint Mary's University, Halifax, NS, B3H 3C3 (Canada); Sommer-Larsen, Jesper, E-mail: razoumov@ap.smu.c, E-mail: jslarsen@astro.ku.d [Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstrasse 2, D-85748 Garching (Germany)

    2010-02-20

    We compute the escape of ionizing radiation from galaxies in the redshift interval z = 4-10, i.e., during and after the epoch of reionization, using a high-resolution set of galaxies, formed in fully cosmological simulations. The simulations invoke early, energetic feedback, and the galaxies evolve into a realistic population at z = 0. Our galaxies cover nearly four orders of magnitude in masses (10{sup 7.8}-10{sup 11.5} M{sub sun}) and more than five orders in star formation rates (10{sup -3.5}-10{sup 1.7} M{sub sun} yr{sup -1}), and we include an approximate treatment of dust absorption. We show that the source-averaged Lyman limit escape fraction at z = 10.4 is close to 80% declining monotonically with time as more massive objects build up at lower redshifts. Although the amount of dust absorption is uncertain to 1-1.5 dex, it is tightly correlated with metallicity; we find that dust is unlikely to significantly impact the observed UV output. These results support reionization by stellar radiation from low-luminosity dwarf galaxies and are also compatible with Lyman continuum observations and theoretical predictions at z {approx} 3-4.

  13. Keck and VLT Observations of Super-damped Lyman-alpha Absorbers at z=2=2.5: Constraints on Chemical Compositions and Physical Conditions

    E-Print Network [OSTI]

    Kulkarni, Varsha P; Morrison, Sean; Peroux, Celine; Quiret, Samuel; York, Donald G

    2015-01-01

    We report Keck/ESI and VLT/UVES observations of three super-damped Lyman-alpha quasar absorbers with H I column densities log N(HI) >= 21.7 at redshifts z=2-2.5. All three absorbers show similar metallicities (-1.3 to -1.5 dex), and dust depletion of Fe, Ni, and Mn. Two of the absorbers show supersolar [S/Zn] and [Si/Zn]. We combine our results with those for other DLAs to examine trends between N(HI), metallicity, dust depletion. A larger fraction of the super-DLAs lie close to or above the line [X/H]=20.59-log N(HI) in the metallicity vs. N(HI) plot, compared to the less gas-rich DLAs, suggesting that super-DLAs are more likely to be rich in molecules. Unfortunately, our data for Q0230-0334 and Q0743+1421 do not cover H2 absorption lines. For Q1418+0718, some H2 lines are covered, but not detected. CO is not detected in any of our absorbers. For DLAs with log N(HI) 21.7 may have somewhat narrower velocity dispersions delta v_90 than the less gas-rich DLAs, and may arise in cooler and/or less turbulent gas.

  14. Carbon and Strontium Abundances of Metal-Poor Stars

    E-Print Network [OSTI]

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

    2007-06-20

    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.

  15. Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data

    E-Print Network [OSTI]

    Lawler, J E; Cowan, J J; Ivans, I I; Hartog, E A Den

    2009-01-01

    Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 921 lines of Ce II. This improved laboratory data set has been used to determine a new solar photospheric Ce abundance, log epsilon = 1.61 +/- 0.01 (sigma = 0.06 from 45 lines), a value in excellent agreement with the recommended meteoritic abundance, log epsilon = 1.61 +/- 0.02. Revised Ce abundances have also been derived for the r-process-rich metal-poor giant stars BD+17 3248, CS 22892-052, CS 31082-001, HD 115444 and HD 221170. Between 26 and 40 lines were used for determining the Ce abundance in these five stars, yielding a small statistical uncertainty of 0.01 dex similar to the Solar result. The relative abundances in the metal-poor stars of Ce and Eu, a nearly pure r-process element in the Sun, matches r-process ...

  16. Delving into X-ray obscuration of type 2 AGN, near and far

    SciTech Connect (OSTI)

    LaMassa, Stephanie M.; Meg Urry, C.; Yaqoob, Tahir; Ptak, Andrew F.; Gandhi, Poshak

    2014-05-20

    Using self-consistent, physically motivated models, we investigate the X-ray obscuration in 19 Type 2 [O III] 5007 Å selected active galactic nuclei (AGNs), 9 of which are local Seyfert 2 galaxies and 10 of which are Type 2 quasar candidates. We derive reliable line-of-sight and global column densities for these objects, which is the first time this has been reported for an AGN sample; four AGNs have significantly different global and line-of-sight column densities. Five sources are heavily obscured to Compton-thick. We comment on interesting sources revealed by our spectral modeling, including a candidate 'naked' Sy2. After correcting for absorption, we find that the ratio of the rest-frame, 2-10 keV luminosity (L{sub 2-10} {sub keV,} {sub in}) to L{sub [O} {sub III]} is 1.54 ± 0.49 dex which is essentially identical to the mean Type 1 AGN value. The Fe K? luminosity is significantly correlated with L{sub [O} {sub III]} but with substantial scatter. Finally, we do not find a trend between L {sub 2-10keV,} {sub in} and global or line-of-sight column density, between column density and redshift, between column density and scattering fraction, or between scattering fraction and redshift.

  17. The naked nuclei of LINERs

    E-Print Network [OSTI]

    Balmaverde, Barbara

    2015-01-01

    We analyze HST spectra and Chandra observations of a sample of 21 LINERs, at least 18 of which genuine AGN. We find a correlation between the X-rays and emission lines luminosities, extending over three orders of magnitude and with a dispersion of 0.36 dex; no differences emerge between LINERs with and without broad lines, or between radio-loud and radio-quiet sources. The presence of such a strong correlation is remarkable considering that for half of the sample the X-ray luminosity can not be corrected for local absorption. This connection is readily understood since the X-ray light is associated with the same source producing the ionizing photons at the origin of the line emission. This implies that we have a direct view of the LINERs nuclei in the X-rays: the circumnuclear, high column density structure (the torus) is absent in these sources. Such a conclusion is also supported by mid-infrared data. We suggest that this is due to the general paucity of gas and dust in their nuclear regions that causes als...

  18. TRACING THE ORIGIN OF THE AQUARIUS STREAM. I

    SciTech Connect (OSTI)

    Wylie-de Boer, Elizabeth; Freeman, Kenneth; Keller, Stefan [Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT 2611 (Australia); Williams, Mary; Steinmetz, Matthias [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Munari, Ulisse, E-mail: ewylie@mso.anu.edu.au, E-mail: kcf@mso.anu.edu.au, E-mail: mary@aip.de [INAF Astronomical Observatory of Padova, 36012 Asiago (Italy)

    2012-08-10

    We present an abundance analysis of six member stars of the recently discovered Aquarius stream, in an attempt to ascertain whether this halo stream is real and, if so, to understand its origin. The mean metallicities of the six stars have a dispersion of only 0.10 dex, indicating that they are part of a chemically coherent structure. We then investigate whether the stream represents the debris of a disrupted dwarf galaxy or a disrupted globular cluster. The [Ni/Fe]-[Na/Fe] plane provides a good diagnostic: globular cluster stars and dwarf spheroidal galaxy stars are well separated in this plane, and the Aquarius stream stars lie unambiguously in the globular cluster region. The Aquarius stream stars also lie on the distinct [Na/Fe]-[O/Fe] and [Mg/Fe]-[Al/Fe] relations delineated by Galactic globular cluster stars. Spectroscopic parameters for the six Aquarius stars show that they are tightly confined to a 12 Gyr, [Fe/H] =-1.0, {alpha}-enhanced isochrone, consistent with their identification as globular cluster debris. We present evidence that the Aquarius stream may continue through the disk and out into the northern halo. Our results indicate a globular cluster origin for the Aquarius stream and demonstrate the potential for chemical tagging to identify the origins of Galactic substructures.

  19. The Baltimore and Utrecht models for cluster dissolution

    E-Print Network [OSTI]

    Henny J. G. L. M. Lamers

    2008-04-14

    The analysis of the age distributions of star cluster samples of different galaxies has resulted in two very different empirical models for the dissolution of star clusters: the Baltimore model and the Utrecht model. I describe these two models and their differences. The Baltimore model implies that the dissolution of star clusters is mass independent and that about 90% of the clusters are destroyed each age dex, up to an age of about a Gyr, after which point mass-dependent dissolution from two-body relaxation becomes the dominant mechanism. In the Utrecht model, cluster dissolution occurs in three stages: (i) mass-independent infant mortality due to the expulsion of gas up to about 10 Myr; (ii) a phase of slow dynamical evolution with strong evolutionary fading of the clusters lasting up to about a Gyr; and (iii) a phase dominated by mass dependent-dissolution, as predicted by dynamical models. I describe the cluster age distributions for mass-limited and magnitude-limited cluster samples for both models. I refrain from judging the correctness of these models.

  20. Triangulum II: A Very Dense Ultra-Faint Dwarf Galaxy

    E-Print Network [OSTI]

    Kirby, Evan N; Simon, Joshua D; Guhathakurta, Puragra

    2015-01-01

    Laevens et al. recently discovered Triangulum II, a satellite of the Milky Way. Its Galactocentric distance is 36 kpc, and its luminosity is only 450 L_sun. We measured the radial velocities of six members stars with Keck/DEIMOS, and we found a velocity dispersion of sigma_v = 5.1 -1.4 +4.0 km/s. We also measured the metallicities of three stars and found a range of 0.8 dex in [Fe/H]. The velocity and metallicity dispersions identify Triangulum II as a dark matter-dominated galaxy. The galaxy is moving very quickly toward the Galactic center (v_GSR = -262 km/s). Although it might be in the process of being tidally disrupted as it approaches pericenter, there is no strong evidence for disruption. The ellipticity is low, and the mean velocity, = -382.1 +/- 2.9 km/s, rules out an association with the Triangulum-Andromeda substructure or the Pan-Andromeda Archaeological Survey (PAndAS) stellar stream. If Triangulum II is in dynamical equilibrium, then it would have a mass-to-light ratio of 3600 -2100 +3500 M_sun...

  1. 3D Model Atmospheres for Extremely Low-Mass White Dwarfs

    E-Print Network [OSTI]

    Tremblay, P -E; Kilic, M; Ludwig, H -G; Steffen, M; Freytag, B; Hermes, J J

    2015-01-01

    We present an extended grid of mean three-dimensional (3D) spectra for low-mass, pure-hydrogen atmosphere DA white dwarfs (WDs). We use CO5BOLD radiation-hydrodynamics 3D simulations covering Teff = 6000-11,500 K and logg = 5-6.5 (cgs units) to derive analytical functions to convert spectroscopically determined 1D temperatures and surface gravities to 3D atmospheric parameters. Along with the previously published 3D models, the 1D to 3D corrections are now available for essentially all known convective DA WDs (i.e., logg = 5-9). For low-mass WDs, the correction in temperature is relatively small (a few per cent at the most), but the surface gravities measured from the 3D models are lower by as much as 0.35 dex. We revisit the spectroscopic analysis of the extremely low-mass (ELM) WDs, and demonstrate that the 3D models largely resolve the discrepancies seen in the radius and mass measurements for relatively cool ELM WDs in eclipsing double WD and WD + milli-second pulsar binary systems. We also use the 3D cor...

  2. nIFTY galaxy cluster simulations III: The Similarity & Diversity of Galaxies & Subhaloes

    E-Print Network [OSTI]

    Elahi, Pascal J; Pearce, Frazer R; Power, Chris; Yepes, Gustavo; Cui, Weiguang; Cunnama, Daniel; Kay, Scott T; Sembolini, Federico; Beck, Alexander M; Davé, Romeel; February, Sean; Huang, Shuiyao; Katz, Neal; McCarthy, Ian G; Murante, Giuseppe; Perret, Valentin; Puchwein, Ewald; Saro, Alexandro; Teyssier, Romain

    2015-01-01

    We examine subhaloes and galaxies residing in a simulated LCDM galaxy cluster ($M^{\\rm crit}_{200}=1.1\\times10^{15}M_\\odot/h$) produced by hydrodynamical codes ranging from classic Smooth Particle Hydrodynamics (SPH), newer SPH codes, an adaptive mesh code and a moving mesh scheme. These codes use subgrid models to capture galaxy formation physics. We compare how well these codes reproduce the same subhaloes/galaxies in gravity only, non-radiative hydrodynamics and full radiative physics runs by looking at the overall subhalo/galaxy distribution and on an individual objects basis. We find the subhalo population is reproduced to within $\\lesssim10\\%$ for both dark matter only and non-radiative runs, with individual objects showing code-to-code scatter of $\\lesssim0.1$ dex, although the gas in non-radiative simulations shows significant scatter. Including radiative physics significantly increases the diversity seen. The subhalo mass and $V_{max}$ distributions vary by $\\approx20\\%$, a result of feedback moving ...

  3. A very reduced upper limit on the interstellar abundance of beryllium

    E-Print Network [OSTI]

    Guillaume Hébrard; Martin Lemoine; Roger Ferlet; Alfred Vidal-Madjar

    1997-02-26

    We present the results of observations of the $\\lambda 3130.4$ \\AA interstellar absorption line of Be II in the direction of zeta Per. The data were obtained at the Canada-France-Hawaii 3.6m Telescope using the Coud\\'e f/4 Gecko spectrograph at a resolving power $\\simeq 1.1 \\times 10^5$, and a signal-to-noise ratio S/N $\\simeq$ 2000. The Be II line is not detected, and we obtain an upper limit on the equivalent width $W_{3130.4}\\leq30$ $\\mu$\\AA. This upper limit is 7 times below the lowest upper limit ever reported hitherto. The derived interstellar abundance is ($^9$Be/H) $\\leq 7 \\times 10^{-13}$, not corrected for the depletion of Be onto interstellar grains; it corresponds to an upper limit $\\delta_{Be} \\leq -1.5$ dex on the depletion factor of Be. As such, it argues in favour of models of formation of dust grains in stellar atmospheres.

  4. Spectroscopic Study on the Beryllium Abundances of Red Giant Stars

    E-Print Network [OSTI]

    Takeda, Yoichi

    2014-01-01

    An extensive spectroscopic study was carried out for the beryllium abundances of 200 red giants (mostly of late G and early K type), which were determined from the near-UV Be II 3131.066 line based on high-dispersion spectra obtained by Subaru/HDS, with an aim of investigating the nature of surface Be contents in these evolved giants; e.g., dependence upon stellar parameters, degree of peculiarity along with its origin and build-up timing. We found that Be is considerably deficient (to widely different degree from star to star) in the photosphere of these evolved giants by ~1-3 dex (or more) compared to the initial abundance. While the resulting Be abundances (A(Be)) appear to weakly depend upon T_eff, log g, [Fe/H], M, age, and v_sin i, this may be attributed to the metallicity dependence of A(Be) coupled with the mutual correlation between these stellar parameters, since such tendencies almost disappear in the metallicity-scaled Be abundance ([Be/Fe]). By comparing the Be abundances (as well as their correl...

  5. The GAPS Programme with HARPS-N@TNG V. A comprehensive analysis of the XO-2 stellar and planetary systems

    E-Print Network [OSTI]

    Damasso, M; Bonomo, A S; Desidera, S; Lanza, A F; Nascimbeni, V; Esposito, M; Scandariato, G; Sozzetti, A; Cosentino, R; Gratton, R; Malavolta, L; Rainer, M; Gandolfi, D; Poretti, E; Sanchez, R Zanmar; Ribas, I; Santos, N; Affer, L; Andreuzzi, G; Barbieri, M; Bedin, L R; Benatti, S; Bernagozzi, A; Bertolini, E; Bonavita, M; Borsa, F; Borsato, L; Boschin, W; Calcidese, P; Carbognani, A; Cenadelli, D; Christille, J M; Claudi, R U; Covino, E; Cunial, A; Giacobbe, P; Granata, V; Harutyunyan, A; Lattanzi, M G; Leto, G; Libralato, M; Lodato, G; Lorenzi, V; Mancini, L; Fiorenzano, A F Martinez; Marzari, F; Masiero, S; Micela, G; Molinari, E; Molinaro, M; Munari, U; Murabito, S; Pagano, I; Pedani, M; Piotto, G; Rosenberg, A; Silvotti, R; Southworth, J

    2015-01-01

    XO-2 is the first confirmed wide stellar binary system where the almost twin components XO-2N and XO-2S have planets. This stimulated a detailed characterization study of the stellar and planetary components based on new observations. We collected high-resolution spectra with the HARPS-N spectrograph and multi-band light curves. Spectral analysis led to an accurate determination of the stellar atmospheric parameters and characterization of the stellar activity. We collected 14 transit light curves of XO-2Nb used to improve the transit parameters. Photometry provided accurate magnitude differences between the stars and a measure of their rotation periods. The iron abundance of XO-2N was found to be +0.054 dex greater, within more than 3-sigma, than that of XO-2S. We confirm a long-term variation in the radial velocities of XO-2N, and we detected a turn-over with respect to previous measurements. We suggest the presence of a second massive companion in an outer orbit or the stellar activity cycle as possible ca...

  6. Thorium-rich halo star HD221170: further evidence against the universality of the r-process

    E-Print Network [OSTI]

    Alexander Yushchenko; Vera Gopka; Stephane Goriely; Faig Musaev; Angelina Shavrina; Chulhee Kim; Young Woon Kang; Juliana Kuznietsova; Vladimir Yushchenko

    2004-09-22

    We report the abundance determination in the atmosphere of the bright halo star HD221170. The spectra were taken with the Terskol Observatory's 2.0-m telescope with a resolution R=45000 and signal-to-noise ratio up to 250 in the wavelength region 3638-10275 \\AA. The adopted atmospheric parameters correspond to an effective temperature \\Tef=4475 K, a surface gravity \\lgg=1.0, a microturbulent velocity \\vmi=1.7 \\kms, and a macroturbulent velocity \\vma=4 \\kms. The abundances of 43 chemical elements were determined with the method of spectrum synthesis. The large overabundances (by 1 dex relative to iron) of elements with Z$>38$ are shown to follow the same pattern as the solar r-abundances. The present HD221170 analysis confirms the non-universality of the r-process, or more exactly the observation that the astrophysical sites hosting the r-process do not always lead to a unique relative abundance distribution for the bulk Ba to Hg elements, the Pb-peak elements, and the actinides.

  7. A NEW COSMOLOGICAL DISTANCE MEASURE USING ACTIVE GALACTIC NUCLEUS X-RAY VARIABILITY

    SciTech Connect (OSTI)

    Franca, Fabio La; Bianchi, Stefano; Branchini, Enzo; Matt, Giorgio [Dipartimento di Matematica e Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146, Roma (Italy); Ponti, Gabriele, E-mail: lafranca@fis.uniroma3.it [Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany)

    2014-05-20

    We report the discovery of a luminosity distance estimator using active galactic nuclei (AGNs). We combine the correlation between the X-ray variability amplitude and the black hole (BH) mass with the single-epoch spectra BH mass estimates which depend on the AGN luminosity and the line width emitted by the broad-line region. We demonstrate that significant correlations do exist that allow one to predict the AGN (optical or X-ray) luminosity as a function of the AGN X-ray variability and either the H? or the Pa? line widths. In the best case, when the Pa? is used, the relationship has an intrinsic dispersion of ?0.6 dex. Although intrinsically more disperse than supernovae Ia, this relation constitutes an alternative distance indicator potentially able to probe, in an independent way, the expansion history of the universe. With respect to this, we show that the new mission concept Athena should be able to measure the X-ray variability of hundreds of AGNs and then constrain the distance modulus with uncertainties of 0.1 mag up to z ? 0.6. We also discuss how our estimator has the prospect of becoming a cosmological probe even more sensitive than the current supernovae Ia samples by using a new dedicated wide-field X-ray telescope able to measure the variability of thousands of AGNs.

  8. Metallicities of M Dwarf Planet Hosts from Spectral Synthesis

    E-Print Network [OSTI]

    Jacob L. Bean; G. Fritz Benedict; Michael Endl

    2006-11-02

    We present the first spectroscopic metallicities of three M dwarfs with known or candidate planetary mass companions. We have analyzed high resolution, high signal-to-noise spectra of these stars which we obtained at McDonald Observatory. Our analysis technique is based on spectral synthesis of atomic and molecular features using recently revised cool-star model atmospheres and spectrum synthesis code. The technique has been shown to yield results consistent with the analyses of solar-type stars and allows measurements of M dwarf [M/H] values to 0.12 dex precision. From our analysis, we find [M/H] = -0.12, -0.32, and -0.33 for GJ 876, GJ 436, and GJ 581 respectively. These three M dwarf planet hosts have sub-solar metallicities, a surprising departure from the trend observed in FGK-type stars. This study is the first part of our ongoing work to determine the metallicities of the M dwarfs included in the McDonald Observatory planet search program.

  9. A New Color-Magnitude Diagram for Palomar 11

    E-Print Network [OSTI]

    M. S. Lewis; W. M. Liu; N. E. Q. Paust; Brian Chaboyer

    2006-01-13

    We present new photometry for the Galactic thick disk globular cluster Palomar 11 extending well past the main sequence turn-off in the V and I bands. This photometry shows noticeable red giant and subgiant branches. The difference in magnitude between the red horizontal branch (red clump) and the subgiant branch is used to determine that Palomar 11 has an age of 10.4+/-0.5 Gyr. The red clump is used to derive a distance d_\\sun=14.3+/-0.4 kpc, and a mean cluster reddening of E(V-I)=0.40+/-0.03. There is differential reddening across the cluster, of order \\delta E(V-I)~0.07. The colour magnitude diagram of Palomar 11 is virtually identically to that of the thick disk globular cluster NGC 5927, implying that these two clusters have a similar age and metallicity. Palomar 11 has a slightly redder red giant branch than 47 Tuc, implying that Palomar 11 is 0.15 dex more metal-rich, or 1 Gyr older than 47 Tuc. Ca II triplet observations (Rutledge et al. 1997) favour the hypothesis that Palomar 11 is the same age as 47 Tuc, but slightly more metal-rich.

  10. Dark-ages reionization & galaxy formation simulation IV: UV luminosity functions of high-redshift galaxies

    E-Print Network [OSTI]

    Liu, Chuanwu; Angel, P W; Duffy, Alan R; Geil, Paul M; Poole, Gregory B; Mesinger, Andrei; Wyithe, J Stuart B

    2015-01-01

    In this paper we present calculations of the UV luminosity function predictions from the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulations (DRAGONS) project, which combines N-body, semi-analytic and semi-numerical modeling designed to study galaxy formation during the Epoch of Reionization. Using galaxy formation physics including supernova feedback, the model naturally reproduces the UV LFs for high-redshift star-forming galaxies from $z{\\sim}5$ through to $z{\\sim}10$. We investigate the predicted luminosity-star formation rate (SFR) relation, finding that variable SFR histories of galaxies result in a scatter around the mean relation of $0.1$-$0.3$ dex depending on UV luminosity. We find close agreement between the model and observationally derived SFR functions. We use our predicted luminosities to investigate the luminosity function below current detection limits, and the ionizing photon budget for reionization. We predict that the slope of the UV LF remains steep below cu...

  11. Operators Manual and Technical Reference for the Z-Beamlet Phase Modulation Failsafe System: Version 1.

    SciTech Connect (OSTI)

    Armstrong, Darrell J.

    2014-09-01

    The need for pulse energies exceeding 4 kJ and pulse lengths [?] 2 ns in Sandia's Z-Beamlet laser (ZBL) requires that the single-frequency spectrum of its fiber-laser master oscillator be converted to a phase modulated spectrum with a modulation in dex [?] 5. Because accidental injection of single-frequency light into ZBL could result i n damage to optical materials from transverse stimulated Brillouin scattering, the presence of phase modulated (PM) light must be monitored by a reliable failsafe system that can stop a las er shot within of a few 10's of ns following a failure of the PM system. This requirement is met by combining optical heterodyne detection with high-speed electronics to indicate the pres ence or absence of phase modulated light. The transition time for the failsafe signal resultin g from a sudden failure using this technique is approximately 35 ns. This is sufficiently short to safely stop a single-frequency laser pulse from leaving ZBL's regenerative amplifier with a n approximately 35 ns margin of safety. This manual and technical reference contains detai led instructions for daily use of the PM failsafe system and provides enough additional informat ion for its maintenance and repair.

  12. Z-FIRE: ISM properties of the z = 2.095 COSMOS Cluster

    E-Print Network [OSTI]

    Kewley, Lisa J; Nanayakkara, Themiya; Kacprzak, Glenn G; Tran, Kim-Vy H; Glazebrook, Karl; Spitler, Lee; Cowley, Michael; Dopita, Michael; Straatman, Caroline; Labbe, Ivo; Tomczak, Adam

    2015-01-01

    We investigate the ISM properties of 13 star-forming galaxies within the z~2 COSMOS cluster. We show that the cluster members have [NII]/Ha and [OIII]/Hb emission-line ratios similar to z~2 field galaxies, yet systematically different emission-line ratios (by ~0.17 dex) from the majority of local star-forming galaxies. We find no statistically significant difference in the [NII]/Ha and [OIII]/Hb line ratios or ISM pressures among the z~2 cluster galaxies and field galaxies at the same redshift. We show that our cluster galaxies have significantly larger ionization parameters (by up to an order of magnitude) than local star-forming galaxies. We hypothesize that these high ionization parameters may be associated with large specific star formation rates (i.e. a large star formation rate per unit stellar mass). If this hypothesis is correct, then this relationship would have important implications for the geometry and/or the mass of stars contained within individual star clusters as a function of redshift.

  13. Normal and outlying populations of the Milky Way stellar halo at [Fe/H] <–2

    SciTech Connect (OSTI)

    Cohen, Judith G.; Christlieb, Norbert; Thompson, Ian; McWilliam, Andrew; Shectman, Stephen; Reimers, Dieter; Wisotzki, Lutz; Kirby, Evan E-mail: N.Christlieb@lsw.uni-heidelberg.de E-mail: shec@obs.carnegiescience.edu E-mail: dreimers@hs.uni-hamburg.de E-mail: ekirby@uci.edu

    2013-11-20

    From detailed abundance analysis of >100 Hamburg/ESO candidate extremely metal-poor (EMP) stars we find 45 with [Fe/H] < –3.0 dex. We identify a heretofore unidentified group: Ca-deficient stars with sub-solar [Ca/Fe] ratios and the lowest neutron-capture abundances; the Ca-deficient group comprises ?10% of the sample, excluding Carbon stars. Our radial velocity distribution shows that the carbon-enhanced stars with no s-process enhancements, CEMP-no, and which do not show C{sub 2} bands are not preferentially binary systems. Ignoring Carbon stars, approximately 15% of our sample are strong (?5?) outliers in one or more elements between Mg and Ni; this rises to ?19% if very strong (?10?) outliers for Sr and Ba are included. Examples include: HE0305–0554 with the lowest [Ba/H] known; HE1012–1540 and HE2323–0256, two (non-velocity variable) C-rich stars with very strong [Mg,Al/Fe] enhancements; and HE1226–1149, an extremely r-process rich star.

  14. Stellar masses from the CANDELS survey: the GOODS-South and UDS fields

    E-Print Network [OSTI]

    Santini, P; Fontana, A; Mobasher, B; Barro, G; Castellano, M; Finkelstein, S L; Grazian, A; Hsu, L T; Lee, B; Lee, S -K; Pforr, J; Salvato, M; Wiklind, T; Wuyts, S; Almaini, O; Cooper, M C; Galametz, A; Weiner, B; Amorin, R; Boutsia, K; Conselice, C J; Dahlen, T; Dickinson, M E; Giavalisco, M; Grogin, N A; Guo, Y; Hathi, N P; Kocevski, D; Koekemoer, A M; Kurczynski, P; Merlin, E; Mortlock, A; Newman, J A; Paris, D; Pentericci, L; Simons, R; Willner, S P

    2014-01-01

    We present the public release of the stellar mass catalogs for the GOODS-S and UDS fields obtained using some of the deepest near-IR images available, achieved as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) project. We combine the effort from ten different teams, who computed the stellar masses using the same photometry and the same redshifts. Each team adopted their preferred fitting code, assumptions, priors, and parameter grid. The combination of results using the same underlying stellar isochrones reduces the systematics associated with the fitting code and other choices. Thanks to the availability of different estimates, we can test the effect of some specific parameters and assumptions on the stellar mass estimate. The choice of the stellar isochrone library turns out to have the largest effect on the galaxy stellar mass estimates, resulting in the largest distributions around the median value (with a semi interquartile range larger than 0.1 dex). On the other ha...

  15. CALIBRATING C-IV-BASED BLACK HOLE MASS ESTIMATORS

    SciTech Connect (OSTI)

    Park, Daeseong; Woo, Jong-Hak; Shin, Jaejin [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Denney, Kelly D., E-mail: pds2001@astro.snu.ac.kr, E-mail: woo@astro.snu.ac.kr, E-mail: jjshin@astro.snu.ac.kr, E-mail: kelly@dark-cosmology.dk [Dark Cosmology Centre, Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark)

    2013-06-20

    We present the single-epoch black hole mass estimators based on the C IV {lambda}1549 broad emission line, using the updated sample of the reverberation-mapped active galactic nuclei and high-quality UV spectra. By performing multi-component spectral fitting analysis, we measure the C IV line widths (FWHM{sub C{sub IV}} and line dispersion, {sigma}{sub C{sub IV}}) and the continuum luminosity at 1350 A (L{sub 1350}) to calibrate the C-IV-based mass estimators. By comparing with the H{beta} reverberation-based masses, we provide new mass estimators with the best-fit relationships, i.e., M{sub BH}{proportional_to}L{sub 1350}{sup 0.50{+-}0.07}{sigma}{sub C{sub IV}{sup 2}} and M{sub BH}{proportional_to}L{sub 1350}{sup 0.52{+-}0.09} FWHM{sub C{sub IV}{sup 0.56{+-}0.48}}. The new C-IV-based mass estimators show significant mass-dependent systematic difference compared to the estimators commonly used in the literature. Using the published Sloan Digital Sky Survey QSO catalog, we show that the black hole mass of high-redshift QSOs decreases on average by {approx}0.25 dex if our recipe is adopted.

  16. de r eche r che INSTITUT NATIONAL DE RECHERCHE EN INFORMATIQUE ET EN AUTOMATIQUE

    E-Print Network [OSTI]

    Girault, Alain

    embarqu#s R#sum# : Ce rapport expose les probl#mes li#s # la tol#rance aux pannes dans les syst#mes r Architecture, SynDEx, ordonnancement statique, heuris­ tiques de r#partition. #12; Fault­Tolerant Static

  17. sistemA de CotAs PArA negros dA

    E-Print Network [OSTI]

    Maier, Rudolf Richard

    Decanato de Extensão (DEX) thérèse Hofmann gatti rodrigues da Costa Decanato de Pesquisa e Pós Planejamento e Orçamento (DPO) Carlos Alberto müller lima torres Diretor-Geral Paulo Henrique Portela de edivânio Alves nogueira Coordenador de Educação Corporativa e Eventos roger Werkhauser escalante

  18. THE COS/UVES ABSORPTION SURVEY OF THE MAGELLANIC STREAM. II. EVIDENCE FOR A COMPLEX ENRICHMENT HISTORY OF THE STREAM FROM THE FAIRALL 9 SIGHTLINE

    SciTech Connect (OSTI)

    Richter, Philipp; Fechner, Cora [Institut fuer Physik und Astronomie, Universitaet Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, D-14476 Golm (Potsdam) (Germany); Fox, Andrew J. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Wakker, Bart P. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Lehner, Nicolas; Howk, J. Christopher [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Bland-Hawthorn, Joss [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Ben Bekhti, Nadya [Argelander-Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany)

    2013-08-01

    We present a multi-wavelength study of the Magellanic Stream (MS), a massive gaseous structure in the Local Group that is believed to represent material stripped from the Magellanic Clouds. We use ultraviolet, optical and radio data obtained with HST/COS, VLT/UVES, FUSE, GASS, and ATCA to study metal abundances and physical conditions in the Stream toward the quasar Fairall 9. Line absorption in the MS from a large number of metal ions and from molecular hydrogen is detected in up to seven absorption components, indicating the presence of multi-phase gas. From the analysis of unsaturated S II absorption, in combination with a detailed photoionization model, we obtain a surprisingly high {alpha} abundance in the Stream toward Fairall 9 of [S/H] = -0.30 {+-} 0.04 (0.50 solar). This value is five times higher than what is found along other MS sightlines based on similar COS/UVES data sets. In contrast, the measured nitrogen abundance is found to be substantially lower ([N/H] = -1.15 {+-} 0.06), implying a very low [N/{alpha}] ratio of -0.85 dex. The substantial differences in the chemical composition of MS toward Fairall 9 compared to other sightlines point toward a complex enrichment history of the Stream. We favor a scenario, in which the gas toward Fairall 9 was locally enriched with {alpha} elements by massive stars and then was separated from the Magellanic Clouds before the delayed nitrogen enrichment from intermediate-mass stars could set in. Our results support (but do not require) the idea that there is a metal-enriched filament in the Stream toward Fairall 9 that originates in the LMC.

  19. The solar photospheric abundance of hafnium and thorium. Results from CO5BOLD 3D hydrodynamic model atmospheres

    E-Print Network [OSTI]

    Elisabetta Caffau; L. Sbordone; H. -G. Ludwig; P. Bonifacio; M. Steffen; N. T. Behara

    2008-03-25

    Context: The stable element hafnium (Hf) and the radioactive element thorium (Th) were recently suggested as a suitable pair for radioactive dating of stars. The applicability of this elemental pair needs to be established for stellar spectroscopy. Aims: We aim at a spectroscopic determination of the abundance of Hf and Th in the solar photosphere based on a \\cobold 3D hydrodynamical model atmosphere. We put this into a wider context by investigating 3D abundance corrections for a set of G- and F-type dwarfs. Method: High-resolution, high signal-to-noise solar spectra were compared to line synthesis calculations performed on a solar CO5BOLD model. For the other atmospheres, we compared synthetic spectra of CO5BOLD 3D and associated 1D models. Results: For Hf we find a photospheric abundance A(Hf)=0.87+-0.04, in good agreement with a previous analysis, based on 1D model atmospheres. The weak Th ii 401.9 nm line constitutes the only Th abundance indicator available in the solar spectrum. It lies in the red wing of an Ni-Fe blend exhibiting a non-negligible convective asymmetry. Accounting for the asymmetry-related additional absorption, we obtain A(Th)=0.09+-0.03, consistent with the meteoritic abundance, and about 0.1 dex lower than obtained in previous photospheric abundance determinations. Conclusions: Only for the second time, to our knowledge, has am non-negligible effect of convective line asymmetries on an abundance derivation been highlighted. Three-dimensional hydrodynamical simulations should be employed to measure Th abundances in dwarfs if similar blending is present, as in the solar case. In contrast, 3D effects on Hf abundances are small in G- to mid F-type dwarfs and sub-giants, and 1D model atmospheres can be conveniently used.

  20. Decoding the message from meteoritic stardust silicon carbide grains

    SciTech Connect (OSTI)

    Lewis, Karen M.; Lugaro, Maria; Gibson, Brad K.; Pilkington, Kate

    2014-05-02

    SiC mainstream grains are presolar grains believed to form in the envelopes of carbon rich asymptotic giant branch (AGB) stars with masses between 1.5 and 3 solar masses. These grains represent a conundrum as the {sup 29}Si and {sup 30}Si abundances indicate that they formed in stars of super-solar metallicity, before the solar system formed. To shed light on this problem, we use silicon isotopic abundances to derive an age-metallicity relation for the stars believed to have produced the SiC mainstream grains. For 2732 mainstream SiC grains listed in the Presolar Grain Database, we use the {sup 29}Si abundances with the latest galactic chemical evolution (GCE) models to derive [Fe/H], and {sup 30}Si abundances along with the models of Zinner et al. (2006) to determine an approximate birth age for the parent AGB star. Comparing our age-metallicity relation with observational relationships derived for nearby stars, we find that the spread of [Fe/H] is in agreement, but the mean [Fe/H] in our relation is higher by 0.2 dex. We propose that this difference is because stars with higher [Fe/H] produce more dust and thus are over-represented in our age metallicity diagram, a finding consistent with previous published works. This result offers a solution for the long-standing problem of silicon in Stardust SiC grains, confirms the necessity of coupling chemistry and dynamics in simulations of the chemical evolution of our Galaxy, and constrains the modelling of dust condensation in stellar winds as a function of the metallicity.

  1. New insights into the nature of the peculiar star theta Carinae

    E-Print Network [OSTI]

    S. Hubrig; M. Briquet; T. Morel; M. Schoeller; J. F. Gonzalez; P. De Cat

    2008-07-13

    We acquired high resolution spectroscopic and low resolution spectropolarimetric observations to achieve the following goals: a) to improve the orbital parameters to allow a more in-depth discussion on the possibility of mass transfer in the binary system, b) to carry out a non-local thermodynamic equilibrium (NLTE) abundance analysis, and c) to search for the presence of a magnetic field. The study of the radial velocities using CORALIE spectra allowed us to significantly improve the orbital parameters. A comparative NLTE abundance analysis was undertaken for theta Car and two other early B-type stars with recently detected magnetic fields, tau Sco and xi^1 CMa. The analysis revealed significantly different abundance patterns: a one-order-of-magnitude nitrogen overabundance and carbon depletion was found in theta Car, while the oxygen abundance is roughly solar. For the stars xi^1 CMa and tau Sco the carbon abundance is solar and, while an N excess is also detected, it is of much smaller amplitude (0.4-0.6dex). Such an N overabundance is typical of the values already found for other slowly-rotating (magnetic) B-type dwarfs. For theta Car, we attribute instead the chemical peculiarities to a past episode of mass transfer between the two binary components. The results of the search for a magnetic field using FORS1 at the VLT consisting of 26 measurements over a time span of ~1.2h are rather inconclusive: only few measurements have a significance level of 3sigma. Although we detect a periodicity of the order of ~8.8min in the dataset involving the measurements on all hydrogen Balmer lines with the exception of the Halpha and Hbeta lines, these results have to be confirmed by additional time-resolved magnetic field observations.

  2. Comparing the host galaxies of type Ia, type II, and type Ibc supernovae

    SciTech Connect (OSTI)

    Shao, X.; Liang, Y. C.; Chen, X. Y.; Zhong, G. H.; Deng, L. C.; Zhang, B.; Shi, W. B.; Zhou, L. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Dennefeld, M. [Institut d'Astrophysique de Paris, CNRS, and Universite P. et M. Curie, 98bis Bd Arago, F-75014 Paris (France); Hammer, F.; Flores, H., E-mail: xshao@bao.ac.cn, E-mail: ycliang@bao.ac.cn [GEPI, Observatoire de Paris-Meudon, F-92195 Meudon (France)

    2014-08-10

    We compare the host galaxies of 902 supernovae (SNe), including SNe Ia, SNe II, and SNe Ibc, which are selected by cross-matching the Asiago Supernova Catalog with the Sloan Digital Sky Survey (SDSS) Data Release 7. We selected an additional 213 galaxies by requiring the light fraction of spectral observations to be >15%, which could represent well the global properties of the galaxies. Among these 213 galaxies, 135 appear on the Baldwin-Phillips-Terlevich diagram, which allows us to compare the hosts in terms of whether they are star-forming (SF) galaxies, active galactic nuclei (AGNs; including composites, LINERs, and Seyfert 2s) or absorption-line galaxies (Absorps; i.e., their related emission lines are weak or non-existent). The diagrams related to the parameters D{sub n}(4000), H?{sub A}, stellar masses, star formation rates (SFRs), and specific SFRs for the SNe hosts show that almost all SNe II and most of the SNe Ibc occur in SF galaxies, which have a wide range of stellar masses and low D{sub n}(4000). The SNe Ia hosts as SF galaxies following similar trends. A significant fraction of SNe Ia occurs in AGNs and absorption-line galaxies, which are massive and have high D{sub n}(4000). The stellar population analysis from spectral synthesis fitting shows that the hosts of SNe II have a younger stellar population than hosts of SNe Ia. These results are compared with those of the 689 comparison galaxies where the SDSS fiber captures less than 15% of the total light. These comparison galaxies appear biased toward higher 12+log(O/H) (?0.1 dex) at a given stellar mass. Therefore, we believe the aperture effect should be kept in mind when the properties of the hosts for different types of SNe are discussed.

  3. The K giant stars from the LAMOST survey data. I. Identification, metallicity, and distance

    SciTech Connect (OSTI)

    Liu, Chao; Deng, Li-Cai; Li, Jing; Gao, Shuang; Yang, Fan; Xu, Yan; Zhang, Yue-Yang; Xin, Yu; Wu, Yue [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Datun Road 20A, Beijing 100012 (China); Carlin, Jeffrey L.; Newberg, Heidi Jo [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Smith, Martin C. [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Xue, Xiang-Xiang [Max Planck Institute for Astronomy, Königstuhl 17, Heidelberg D-69117 (Germany); Jin, Ge, E-mail: liuchao@nao.cas.cn [University of Science and Technology of China, Hefei 230026 (China)

    2014-08-01

    We present a support vector machine classifier to identify the K giant stars from the LAMOST survey directly using their spectral line features. The completeness of the identification is about 75% for tests based on LAMOST stellar parameters. The contamination in the identified K giant sample is lower than 2.5%. Applying the classification method to about two million LAMOST spectra observed during the pilot survey and the first year survey, we select 298,036 K giant candidates. The metallicities of the sample are also estimated with an uncertainty of 0.13 ? 0.29 dex based on the equivalent widths of Mg{sub b} and iron lines. A Bayesian method is then developed to estimate the posterior probability of the distance for the K giant stars, based on the estimated metallicity and 2MASS photometry. The synthetic isochrone-based distance estimates have been calibrated using 7 globular clusters with a wide range of metallicities. The uncertainty of the estimated distance modulus at K = 11 mag, which is the median brightness of the K giant sample, is about 0.6 mag, corresponding to ?30% in distance. As a scientific verification case, the trailing arm of the Sagittarius stream is clearly identified with the selected K giant sample. Moreover, at about 80 kpc from the Sun, we use our K giant stars to confirm a detection of stream members near the apo-center of the trailing tail. These rediscoveries of the features of the Sagittarius stream illustrate the potential of the LAMOST survey for detecting substructures in the halo of the Milky Way.

  4. Fundamental Parameters and Abundances of Metal-Poor Stars: The SDSS Standard BD +17 4708

    E-Print Network [OSTI]

    I. Ramirez; C. Allende Prieto; S. Redfield; D. L. Lambert

    2006-08-25

    The atmospheric parameters and iron abundance of the Sloan Digital Sky Survey (SDSS) spectrophotometric standard star BD +17 4708 are critically examined using up-to-date Kurucz model atmospheres, LTE line formation calculations, and reliable atomic data. We find Teff = 6141+-50 K, log g = 3.87+-0.08, and [Fe/H]=-1.74+-0.09. The line-of-sight interstellar reddening, bolometric flux, limb-darkened angular diameter, stellar mass, and the abundances of Mg, Si, and Ca are also obtained. This star is a unique example of a moderately metal-poor star for which the effective temperature can be accurately constrained from the observed spectral energy distribution (corrected for reddening). Such analysis leads to a value that is higher than most spectroscopic results previously reported in the literature (~5950 K). We find that the ionization balance of Fe lines is satisfied only if a low Teff (~5950 K) is adopted. With our preferred Teff (6141 K), the mean iron abundance we obtain from the FeII lines is lower by about 0.15 dex than that from the FeI lines, and therefore, the discrepancy between the mean iron abundance from FeI and FeII lines cannot be explained by overionization by UV photons as the main non-LTE effect. We also comment on non-LTE effects and the importance of inelastic collisions with neutral H atoms in the determination of oxygen abundances in metal-poor stars from the 777 nm OI triplet. (Abridged)

  5. Hydrocarbon in Catalyst in

    E-Print Network [OSTI]

    Ladkin, Peter B.

    #12;Hydrocarbon in Steam in Catalyst in Vent 1 Vent 2 Product out Tank Pressure controller Computer;#12;Vent 1 Vent 2 Product outHydrocarbon in Steam in Catalyst in light Warning Computer controller Tank

  6. Hydrocarbon in Catalyst in

    E-Print Network [OSTI]

    Ladkin, Peter B.

    Hydrocarbon in Steam in Catalyst in Vent 1 Vent 2 Product out Tank Pressure #12;#12;#12;#12;#12;#12;#12;#12;Hydrocarbon in Steam in Catalyst in Vent 1 Vent 2 Product out Tank Pressure controller Computer operator

  7. CD Tau: a detached eclipsing binary with a solar-mass companion

    E-Print Network [OSTI]

    Ignasi Ribas; Carme Jordi; Jordi Torra

    1999-05-10

    We present a detailed analysis of the detached eclipsing binary CD Tau. A large variety of observational data, in form of IR photometry, CORAVEL radial velocity observations and high-resolution spectra, are combined with the published light curves to derive accurate absolute dimensions and effective temperature of the components, as well as the metal abundance of the system. We obtain: MA=1.442(16) Mo, RA=1.798(17) Ro, TeffA=6200(50) K, MB=1.368(16) Msun, RB=1.584(20) Run and TeffB=6200(50) K. The metal content of the system is determined to be [Fe/H]=+0.08(15) dex. In addition, the eclipsing binary has a K-type close visual companion at about 10-arcsec separation, which is shown to be physically linked, thus sharing a common origin. The effective temperature of the visual companion (Teff=5250(200) K) is determined from synthetic spectrum fitting, and its luminosity (log L/Lo=-0.27(6)), and therefore its radius (R=0.89(9) Ro), are obtained from comparison with the apparent magnitude of the eclipsing pair. The observed fundamental properties of the eclipsing components are compared with the predictions of evolutionary models, and we obtain good agreement for an age of 2.6 Gyr and a chemical composition of Z=0.026 and Y=0.26. Furthermore, we test the evolutionary models for solar-mass stars and we conclude that the physical properties of the visual companion are very accurately described by the same isochrone that fits the more massive components.

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

    SciTech Connect (OSTI)

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

    2011-08-10

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

  9. A KINE-CHEMICAL INVESTIGATION OF THE AB DOR MOVING GROUP 'STREAM'

    SciTech Connect (OSTI)

    Barenfeld, Scott A.; Bubar, Eric J.; Mamajek, Eric E. [University of Rochester, Department of Physics and Astronomy, Rochester, NY 14627-0171 (United States)] [University of Rochester, Department of Physics and Astronomy, Rochester, NY 14627-0171 (United States); Young, Patrick A. [Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287-1404 (United States)] [Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287-1404 (United States)

    2013-03-20

    The AB Dor Moving Group consists of a 'nucleus' of {approx}10 stars at d {approx_equal} 20 pc, along with dozens of purported 'stream' members distributed across the sky. We perform a chemical and kinematic analysis of a subsample of AB Dor stream stars to test whether they constitute a physical stellar group. We use the NEMO Galactic kinematic code to investigate the orbits of the stream members, and perform a chemical abundance analysis using high resolution spectra taken with the Magellan Clay 6.5 m telescope. Using a {chi}{sup 2} test with the measured abundances for 10 different elements, we find that only half of the purported AB Dor stream members could possibly constitute a statistically chemically homogeneous sample. Some stream members with three-dimensional velocities were hundreds of parsecs from the AB Dor nucleus {approx}10{sup 8} yr ago, and hence were unlikely to share a common origin. We conclude that the published lists of AB Dor moving group stream members are unlikely to represent the dispersed remnant of a single star formation episode. A subsample of the stream stars appears to be both statistically chemically homogeneous and in the vicinity of the AB Dor nucleus at birth. Their mean metallicity is [Fe/H] = 0.02 {+-} 0.02 dex, which we consider representative for the AB Dor group. Finally, we report a strong lower limit on the age of the AB Dor nucleus of >110 Myr based on the pre-main sequence contraction times for K-type members which have reached the main sequence.

  10. THE FUTURE OF THE SUN: AN EVOLVED SOLAR TWIN REVEALED BY CoRoT

    SciTech Connect (OSTI)

    Do Nascimento, J.-D. Jr.; Da Costa, J. S.; Castro, M.; Takeda, Y.; Melendez, J.

    2013-07-10

    The question of whether the Sun is peculiar within the class of solar-type stars has been the subject of active investigation over the past three decades. Although several solar twins have been found with stellar parameters similar to those of the Sun (albeit in a range of Li abundances and with somewhat different compositions), their rotation periods are unknown, except for 18 Sco, which is younger than the Sun and with a rotation period shorter than solar. It is difficult to obtain rotation periods for stars of solar age from ground-based observations, as a low-activity level implies a shallow rotational modulation of their light curves. CoRoT has provided space-based long time series from which the rotation periods of solar twins as old as the Sun could be estimated. Based on high-signal-to-noise, high-resolution spectroscopic observations gathered at the Subaru Telescope, we show that the star CoRoT ID 102684698 is a somewhat evolved solar twin with a low Li abundance. Its rotation period is 29 {+-} 5 days, compatible with its age (6.7 Gyr) and low lithium content, A{sub Li} {approx}< 0.85 dex. Interestingly, our CoRoT solar twin seems to have enhanced abundances of the refractory elements with respect to the Sun, a typical characteristic of most nearby twins. With a magnitude V {approx_equal} 14.1, ID 102684698 is the first solar twin revealed by CoRoT, the farthest field solar twin so far known, and the only solar twin older than the Sun for which a rotation period has been determined.

  11. Uncovering Additional Clues to Galaxy Evolution. II. The Environmental Impact of the Virgo Cluster on the Evolution of Dwarf Irregular Galaxies

    E-Print Network [OSTI]

    Henry Lee; Marshall L. McCall; Michael G. Richer

    2003-03-17

    The impact of the cluster environment on the evolution of dwarf galaxies is investigated by comparing the properties of a sample of dwarf irregulars (dIs) in the Virgo Cluster with a control sample of nearby ("field") dIs having oxygen abundances derived from [O III]4363 measurements and measured distances from resolved stellar constituents. Spectroscopic data are obtained for H II regions in 11 Virgo dIs distributed in the central and outer regions of the cluster. To ensure that oxygen abundances are derived in a homogeneous manner, oxygen abundances for field and Virgo dIs are computed using the bright-line method and compared with abundances directly obtained from [O III]4363, where available. They are found to agree to within about 0.2 dex with no systematic offset. At a given optical luminosity, there is no systematic difference in oxygen abundance between the sample of Virgo dIs and the sample of nearby dIs. However, five of the eleven Virgo dIs exhibit much lower baryonic gas fractions than field dIs at comparable oxygen abundances. Using field dIs as a reference, a gas-deficiency index for dIs is constructed, making it possible quantitatively to identify which galaxies have lost gas. For the Virgo sample, some of the dwarfs are gas-deficient by a factor of 30. The gas-deficiency correlates roughly with the X-ray surface brightness of the intracluster gas. Ram-pressure stripping can best explain the observed gas-poor dIs in the cluster sample. Together with the lack of significant fading and reddening of the gas-poor dIs compared to gas-normal dIs, these observations suggest that the gas-poor dIs in Virgo have recently encountered the intracluster medium for the first time. Faded remnants of gas-poor dIs in Virgo will resemble bright dwarf ellipticals presently seen in the cluster core.

  12. METALLICITIES OF EMISSION-LINE GALAXIES FROM HST ACS PEARS AND HST WFC3 ERS GRISM SPECTROSCOPY AT 0.6 < z < 2.4

    SciTech Connect (OSTI)

    Xia Lifang; Malhotra, Sangeeta; Rhoads, James; Cohen, Seth; Windhorst, Rogier A. [School of Earth and Space Exploration, Arizona State University, AZ 85287-1404 (United States); Pirzkal, Nor [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Straughn, Amber [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Finkelstein, Steven [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Kuntschner, Harald; Kuemmel, Martin; Walsh, Jeremy [European Southern Observatory, Karl Schwarzschild Str. 2, D-85748 Garching (Germany); O'Connell, Robert, E-mail: lifang.xia@asu.edu [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)

    2012-07-15

    Galaxies selected on the basis of their emission-line strength show low metallicities, regardless of their redshifts. We conclude this from a sample of faint galaxies at redshifts between 0.6 < z < 2.4, selected by their prominent emission lines in low-resolution grism spectra in the optical with the Advanced Camera for Surveys on the Hubble Space Telescope and in the near-infrared using Wide-Field Camera 3. Using a sample of 11 emission-line galaxies at 0.6 < z < 2.4 with luminosities of -22 {approx}< M{sub B} {approx}< -19 which have [O II], H{beta}, and [O III] line flux measurements from the combination of two grism spectral surveys, we use the R23 method to derive the gas-phase oxygen abundances: 7.5 < 12 + log (O/H) < 8.5. The galaxy stellar masses are derived using Bayesian-based Markov Chain Monte Carlo ({pi}MC{sup 2}) fitting of their spectral energy distribution, and span the mass range 8.1 < log (M{sub *}/M{sub Sun} ) < 10.1. These galaxies show mass-metallicity (M-Z) and luminosity-metallicity (L-Z) relations, which are offset by -0.6 dex in metallicity at given absolute magnitude and stellar mass relative to the local Sloan Digital Sky Survey galaxies, as well as continuum-selected DEEP2 samples at similar redshifts. The emission-line-selected galaxies most resemble the local 'green peas' galaxies and Ly{alpha} galaxies at z {approx_equal} 0.3 and z {approx_equal} 2.3 in the M-Z and L-Z relations and their morphologies. The G - M{sub 20} morphology analysis shows that 10 out of 11 show disturbed morphology, even as the star-forming regions are compact. These galaxies may be intrinsically metal poor, being at early stages of formation, or the low metallicities may be due to gas infall and accretion due to mergers.

  13. PROBING THE LOW-REDSHIFT STAR FORMATION RATE AS A FUNCTION OF METALLICITY THROUGH THE LOCAL ENVIRONMENTS OF TYPE II SUPERNOVAE

    SciTech Connect (OSTI)

    Stoll, R.; Stanek, K. Z.; Pogge, R. W. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210-1173 (United States); Prieto, J. L. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544 (United States)

    2013-08-10

    Type II supernovae (SNe) can be used as a star formation tracer to probe the metallicity distribution of global low-redshift star formation. We present oxygen and iron abundance distributions of Type II SN progenitor regions that avoid many previous sources of bias. Because iron abundance, rather than oxygen abundance, is of key importance for the late stage evolution of the massive stars that are the progenitors of core-collapse supernovae, and because iron enrichment lags oxygen enrichment, we find a general conversion from oxygen abundance to iron abundance. The distributions we present here are the best yet observational standard of comparison for evaluating how different classes of supernovae depend on progenitor metallicity. We spectroscopically measure the gas-phase oxygen abundance near a representative subsample of the hosts of Type II SNe from the first-year Palomar Transient Factory (PTF) SN search, using a combination of Sloan Digital Sky Survey (SDSS) spectra near the SN location (9 hosts) and new longslit spectroscopy (25 hosts). The median metallicity of these 34 hosts at or near the SN location is 12+log(O/H) = 8.65, with a median error of 0.09. The median host galaxy stellar mass from fits to SDSS photometry is 10{sup 9.9} M{sub Sun }. They do not show a systematic offset in metallicity or mass from a redshift-matched sample of the MPA/JHU value-added catalog. In contrast to previous SN host metallicity studies, this sample is drawn from a single survey. It is also drawn from an areal rather than a targeted survey, so SNe in the lowest-mass galaxies are not systematically excluded. Indeed, the PTF SN search has a slight bias toward following up transients in low mass galaxies. The progenitor region metallicity distribution we find is statistically indistinguishable from the metallicity distribution of Type II SN hosts found by targeted surveys and by samples from multiple surveys with different selection functions. Using the relationship between iron and oxygen abundances found for Milky Way disk, bulge, and halo stars, we translate our distribution of Type II SN environments as a function of oxygen abundance into an estimate of the iron abundance, since iron varies more steeply than oxygen. We find that though this sample spans only 0.65 dex in oxygen abundance, the gap between the iron and oxygen abundance is 50% wider at the low-metallicity end of our sample than at the high-metallicity end.

  14. TU-F-17A-08: The Relative Accuracy of 4D Dose Accumulation for Lung Radiotherapy Using Rigid Dose Projection Versus Dose Recalculation On Every Breathing Phase

    SciTech Connect (OSTI)

    Lamb, J; Lee, C; Tee, S; Lee, P; Iwamoto, K; Low, D; Valdes, G; Robinson, C

    2014-06-15

    Purpose: To investigate the accuracy of 4D dose accumulation using projection of dose calculated on the end-exhalation, mid-ventilation, or average intensity breathing phase CT scan, versus dose accumulation performed using full Monte Carlo dose recalculation on every breathing phase. Methods: Radiotherapy plans were analyzed for 10 patients with stage I-II lung cancer planned using 4D-CT. SBRT plans were optimized using the dose calculated by a commercially-available Monte Carlo algorithm on the end-exhalation 4D-CT phase. 4D dose accumulations using deformable registration were performed with a commercially available tool that projected the planned dose onto every breathing phase without recalculation, as well as with a Monte Carlo recalculation of the dose on all breathing phases. The 3D planned dose (3D-EX), the 3D dose calculated on the average intensity image (3D-AVE), and the 4D accumulations of the dose calculated on the end-exhalation phase CT (4D-PR-EX), the mid-ventilation phase CT (4D-PR-MID), and the average intensity image (4D-PR-AVE), respectively, were compared against the accumulation of the Monte Carlo dose recalculated on every phase. Plan evaluation metrics relating to target volumes and critical structures relevant for lung SBRT were analyzed. Results: Plan evaluation metrics tabulated using 4D-PR-EX, 4D-PR-MID, and 4D-PR-AVE differed from those tabulated using Monte Carlo recalculation on every phase by an average of 0.14±0.70 Gy, - 0.11±0.51 Gy, and 0.00±0.62 Gy, respectively. Deviations of between 8 and 13 Gy were observed between the 4D-MC calculations and both 3D methods for the proximal bronchial trees of 3 patients. Conclusions: 4D dose accumulation using projection without re-calculation may be sufficiently accurate compared to 4D dose accumulated from Monte Carlo recalculation on every phase, depending on institutional protocols. Use of 4D dose accumulation should be considered when evaluating normal tissue complication probabilities as well as in clinical situations where target volumes are directly inferior to mobile critical structures.

  15. IN SICKNESS AND IN HEALTH

    E-Print Network [OSTI]

    Hill, Wendell T.

    IN SICKNESS AND IN HEALTH #12;The UHC Cares for YOU! #12;#12;ABOUTUS Location;HERE'S ONLY SOME OF WHAT WE CAN DO FORYOU! Health Clinic Health Health Health

  16. New colour-transformations for the Sloan photometry and revised metallicity calibration and equations for photometric parallax estimation

    E-Print Network [OSTI]

    S. Karaali; S. Bilir; S. Tuncel

    2004-07-13

    We evaluated new colour-transformations for the Sloan photometry by 224 standards and used them to revise both the equations for photometric parallax estimation and metallicity calibration cited by Karaali et al. (2003). This process improves the metallicity and absolute magnitude estimations by [Fe/H]<=0.3 dex and M^{H}_{g} <= 0.1 mag respectively. There is a high correlation for metallicities and absolute magnitudes derived for two systems, UBV and Sloan, by means of the revised calibrations.

  17. OPPORTUNITIES IN

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

    in Science and Nature on early supernova evolution, energization of the radiation belts, weathering of rocks on Mars, thunderstorm disruption of the ionosphere, and the...

  18. In progress

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInInInIn

  19. In progress

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInInInInNo data

  20. In Memoriam

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation CurrentHenry Bellamy,Impact AssessmentsImprovingIn Case of DifficultyInIn

  1. Federal Participation in LEED in 2005

    E-Print Network [OSTI]

    Payne, Christopher; Dyer, Beverly

    2005-01-01

    Federal Participation in LEED. In Proceedings, GreenbuildFederal Participation in LEED in 2005 Christopher PayneEnergy & Environmental Design (LEED) Green Building Rating

  2. InDemandInDemandInDemand Energize Your Career

    E-Print Network [OSTI]

    Wolberg, George

    InDemandInDemandInDemand Energize Your Career You can join the next generation of workers who in Energy #12;#12;In Demand | 1 No, this isn't a quiz...but if you answered yes to any or all and Training Administration wants you to have this publication, In Demand: Careers in Energy. It will let you

  3. In Focus

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory ofDid you notHeat Pumps Heat Pumpsfacility doe logoIn Focus Our Vision

  4. Estimating stellar atmospheric parameters based on LASSO and support-vector regression

    E-Print Network [OSTI]

    Lu, Yu

    2015-01-01

    A scheme for estimating atmospheric parameters T$_{eff}$, log$~g$, and [Fe/H] is proposed on the basis of Least Absolute Shrinkage and Selection Operator (LASSO) algorithm and Haar wavelet. The proposed scheme consists of three processes. A spectrum is decomposed using the Haar wavelet transform and low-frequency components at the fourth level are considered as candidate features. Then, spectral features from the candidate features are detected using the LASSO algorithm to estimate the atmospheric parameters. Finally, atmospheric parameters are estimated from the extracted spectral features using the support-vector regression (SVR) method. The proposed scheme was evaluated using three sets of stellar spectra respectively from Sloan Digital Sky Survey (SDSS), Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST), and Kurucz's model, respectively. The mean absolute errors are as follows: for 40~000 SDSS spectra, 0.0062 dex for log~T$_{eff}$ (85.83 K for T$_{eff}$), 0.2035 dex for log$~g$ and 0.1512...

  5. University Roles in Technological Innovation in California

    E-Print Network [OSTI]

    King, C. Judson

    2007-01-01

    Roles in Technological Innovation Eyal Press and JenniferROLES IN TECHNOLOGICAL INNOVATION IN CALIFORNIA 1 May 2007through technological innovation and the formation of

  6. Living in Liminality: Chinese Migrancy in Ghana

    E-Print Network [OSTI]

    Ho, Conal Guan-Yow

    2012-01-01

    Architecture: The Structure of Nationalism in Accra, Ghana. Africaarchitecture style. The National Museum, in These companies included: the United Africa

  7. Iran in History Iran in History

    E-Print Network [OSTI]

    Mohaghegh, Shahab

    1 Iran in History Iran in History by Bernard Lewis In attempting to attain some perspective on Iran. These events have been variously seen in Iran: by some as a blessing, the advent of the true faith, the end remarkable difference between what happened in Iran and what happened in all the other countries

  8. Transport and Pathogenicity of Salmonella enterica Subspecies in Groundwater: In vitro, in vivo, and in silico

    E-Print Network [OSTI]

    Haznedaroglu, Berat Zeki

    2009-01-01

    also assist the bacteria in resistance to antibiotics suchIn Antimicrobial resistance in bacteria of animal origin,of antibiotic resistance in bacteria. Environmental signals

  9. Walkability Planning in Jakarta

    E-Print Network [OSTI]

    Lo, Ria S. Hutabarat

    2011-01-01

    key goals in relation to pedestrian planning? What trends dotransportation and planning in Jakarta in the future?pedestrian research or planning in Indonesia, the notion of

  10. HVEM IN CERAMICS RESEARCH

    E-Print Network [OSTI]

    Thomas, G.

    2010-01-01

    DOCUMENTS SECTION tnnaM IN CERAMICS RESEARCH Gareth Thomaswell to problems in ceramics. In previous conferencesproperties re- lationships in ceramic materials lags ,,'eU

  11. Federal Participation in LEED in 2005

    SciTech Connect (OSTI)

    Payne, Christopher; Dyer, Beverly

    2005-11-01

    The federal government is an active participant in promotingsustainable design, construction and operations and in the use of USGBC'sLeadership in Energy and Environmental Design (LEED) Green BuildingRating System. This paper presents an overview of sustainableconstruction activities in the federal sector in 2005.

  12. Neuroinflammation in Alzheimer's disease

    E-Print Network [OSTI]

    2015-01-01

    pathogens. Activation of the proteolytic complement cascade results in opsonisation and, ultimately, in lysis of microorganisms.

  13. Overcoming ambiguities in decentralisation

    E-Print Network [OSTI]

    Richner, Heinz

    such challenges of local governance. Sustaining local governance in Kerala (India) In Kerala decentralisation

  14. Divorce in Scotland 

    E-Print Network [OSTI]

    Wasoff, Fran

    This briefing explored divorce in Scotland, setting it in its historical context, and examining recent trends.

  15. THE MASS DEPENDENCE BETWEEN PROTOPLANETARY DISKS AND THEIR STELLAR HOSTS

    SciTech Connect (OSTI)

    Andrews, Sean M.; Rosenfeld, Katherine A.; Kraus, Adam L.; Wilner, David J., E-mail: sandrews@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-07-10

    We present a substantial extension of the millimeter (mm) wave continuum photometry catalog for circumstellar dust disks in the Taurus star-forming region, based on a new ''snapshot'' {lambda} = 1.3 mm survey with the Submillimeter Array. Combining these new data with measurements in the literature, we construct a mm-wave luminosity distribution, f(L{sub mm}), for Class II disks that is statistically complete for stellar hosts with spectral types earlier than M8.5 and has a 3{sigma} depth of roughly 3 mJy. The resulting census eliminates a longstanding selection bias against disks with late-type hosts, and thereby demonstrates that there is a strong correlation between L{sub mm} and the host spectral type. By translating the locations of individual stars in the Hertzsprung-Russell diagram into masses and ages, and adopting a simple conversion between L{sub mm} and the disk mass, M{sub d} , we confirm that this correlation corresponds to a statistically robust relationship between the masses of dust disks and the stars that host them. A Bayesian regression technique is used to characterize these relationships in the presence of measurement errors, data censoring, and significant intrinsic scatter: the best-fit results indicate a typical 1.3 mm flux density of {approx}25 mJy for 1 M{sub Sun} hosts and a power-law scaling L{sub mm}{proportional_to}M{sub *}{sup 1.5-2.0}. We suggest that a reasonable treatment of dust temperature in the conversion from L{sub mm} to M{sub d} favors an inherently linear M{sub d} {proportional_to}M{sub *} scaling, with a typical disk-to-star mass ratio of {approx}0.2%-0.6%. The measured rms dispersion around this regression curve is {+-}0.7 dex, suggesting that the combined effects of diverse evolutionary states, dust opacities, and temperatures in these disks imprint a full width at half-maximum range of a factor of {approx}40 on the inferred M{sub d} (or L{sub mm}) at any given host mass. We argue that this relationship between M{sub d} and M{sub *} likely represents the origin of the inferred correlation between giant planet frequency and host star mass in the exoplanet population, and provides some basic support for the core accretion model for planet formation. Moreover, we caution that the effects of incompleteness and selection bias must be considered in comparative studies of disk evolution, and illustrate that fact with statistical comparisons of f(L{sub mm}) between the Taurus catalog presented here and incomplete subsamples in the Ophiuchus, IC 348, and Upper Sco young clusters.

  16. Nanotechnology in Biomaterials: Nanofibers in Tissue Engineering

    E-Print Network [OSTI]

    Hasýrcý, Vasýf

    195 10 Nanotechnology in Biomaterials: Nanofibers in Tissue Engineering Deniz Yucel, Halime Kenar and Chemistry, Middle East Technical University, Ankara, Turkey 10.1 Biomaterials Devices made of synthetic. There are various de nitions of biomaterials expressed in different ways given in the literature, but more or less

  17. Individual variation in cooperative behaviour in meerkats

    E-Print Network [OSTI]

    English, Sinéad

    2010-04-13

    experiences are known to have important and lasting effects on later fitness and behaviour: in Chapter 5, I demonstrate that, in female meerkats only, growing up in a group with more helpers is correlated with reduced cooperation later in life. This result...

  18. Topics in network communications

    E-Print Network [OSTI]

    Cannons, Jillian Leigh

    2008-01-01

    in Electrical Engineering (Communication Theory and Systems)in Electrical Engineering (Communication Theory and Systems)Ph.D. in Electrical Engineering (Communication Theory and

  19. Acid Violence in Pakistan

    E-Print Network [OSTI]

    Zia, Taiba

    2013-01-01

    women’s rights advocate in Pakistan believe that a woman canViolence Legislation in Pakistan,” Huffington Post, Octoberagainst Women in Pakistan. Karachi: Oxford University Press,

  20. Carnage in Sacramento

    E-Print Network [OSTI]

    Brosnan, Douglas

    2009-01-01

    L egislative Carnage in Sacramento Douglas Brosnan, MD, JDpolitical landscape in Sacramento. Since the option of taxMedicine Carnage in Sacramento detention. This bill provides

  1. Spring in Sacramento

    E-Print Network [OSTI]

    Fields, Wesley

    2005-01-01

    41 LETTERS Spring in Sacramento Wesley Fields, MD, FACEPIt is spring again in Sacramento. The fruit trees are inthe rivers that meet in Sacramento. Returning to the capitol

  2. Essays in behavioral economics

    E-Print Network [OSTI]

    Eil, David Holding

    2011-01-01

    Essays in Behavioral Economics A dissertation submitted inDoctor of Philosophy in Economics by David Holding Eilfunction,” The Review of Economics and Statistics, 1995,

  3. In situ groundwater bioremediation

    E-Print Network [OSTI]

    Hazen, Terry C.

    2010-01-01

    degradation of phenols in groundwater. J Contam. Hydrol.Bioimmobilization of Cr(VI) in Groundwater Using Hydrogenof bacterial activity in groundwater containing petroleum

  4. In vivo dosimetry in external beam radiotherapy

    SciTech Connect (OSTI)

    Mijnheer, Ben [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam 1066 CX (Netherlands); Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Izewska, Joanna [Division of Human Health, International Atomic Energy Agency, Vienna 1400 (Austria); Reft, Chester [Department of Radiation and Cellular Oncology, University of Chicago Medical Center, Chicago, Illinois 60637 (United States)

    2013-07-15

    In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.

  5. Understanding pop-ins in spherical nanoindentation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Pathak, Siddhartha; Riesterer, Jessica L.; Kalidindi, Surya R.; Michler, Johann

    2014-10-24

    In this study, pop-ins, or sudden displacement-bursts at constant load in a nanoindentation test, are typically attributed to the difficulty of setting up potent dislocation sources in the very small indentation zones in these experiments. Such displacement (and strain) bursts would intuitively indicate a sharp drop in stress during the pop-in event itself. However, spherical indentation stress-strain curves routinely exhibit a high and stable indentation stress value during the pop-in, and the indentation stresses decrease only after a further finite amount of additional indentation displacement has been applied. In order to understand this discrepancy, we utilize a combination of interruptedmore »spherical indentation tests along with depth profiling of the residual indentation surfaces using in-situ atomic force microscopy (AFM) to study pop-ins. The AFM surface profile maps show that there is an asymmetric profile change over a limited region around the indentation contact area for a single pop-in; the asymmetry disappears upon further loading beyond the pop-in. A plausible sequence of physical processes (related to metal plasticity) occurring underneath the indenter during and immediately after the occurrence of the pop-in is proposed to explain these observations.« less

  6. Recent Trends in Land Tenure in Texas. 

    E-Print Network [OSTI]

    Motheral, Joe

    1944-01-01

    IN TEXAS JOE MOTHERAL Division of Farm and Ranch Economics [Blank Page in Original Bulletin] Public interest in the subject of land tenure has been height- ened by the swift changes, in the tenure pattern of the Southwest during the last decade.... In Texas, Common methods of renting farm land such as the "third-and-fourth" system, which is adapted to the growing of annual cash crops, proved to be inadequate in numerous instances where cotton acreage was reduced and a live- stock program...

  7. Open Season in Sacramento

    E-Print Network [OSTI]

    Brosnan, Douglas

    2009-01-01

    egislative Open Season in Sacramento Douglas Brosnan, MD, JDs open season again in Sacramento: The legislative session

  8. Essays in Energy Economics

    E-Print Network [OSTI]

    MYERS, ERICA CATHERINE

    2014-01-01

    to wholesale electricity prices in Germany. We focus on theWholesale Electricity Prices in Germany,” Economics Letters,

  9. Developments in oil shale in 1987

    SciTech Connect (OSTI)

    Knutson, C.F.; Dana, G.F.; Solti, G.; Qian, J.L.; Ball, F.D.; Hutton, A.C.; Hanna, J.; Russell, P.L.; Piper, E.M.

    1988-10-01

    Oil shale development continued at a slow pace in 1987. The continuing interest in this commodity is demonstrated by the 342 oil shale citations added to the US Department of Energy Energy Database during 1987. The Unocal project in Parachute, Colorado, produced 600,000 bbl of synfuel in 1987. An appreciable amount of 1987's activity was associated with the nonsynfuel uses of oil shale. 4 figs., 2 tabs.

  10. Study Abroad in Global Issues in

    E-Print Network [OSTI]

    of learning and fun opportunities to enjoy natural resources. JOIN US IN this unique opportunity to discover: 3, open to all majors. Housing: Various locations, double occupancy. Costs: $2,650. Including Blacksburg, VA 24061 Wind farm tour in Tilar- an VT students at a Croc- odile farm in San Clara Zip

  11. Eliminating MTBE in Gasoline in 2006

    Reports and Publications (EIA)

    2006-01-01

    A review of the market implications resulting from the rapid change from methyl tertiary butyl ether (MTBE) to ethanol-blended reformulated gasoline (RFG) on the East Coast and in Texas. Strains in ethanol supply and distribution will increase the potential for price volatility in these regions this summer.

  12. Loop formation in polymers in crowded environment

    E-Print Network [OSTI]

    K. Haydukivska; V. Blavatska

    2015-11-12

    We analyze the probability of a single loop formation in a long flexible polymer chain in disordered environment in $d$ dimensions. The structural defects are considered to be correlated on large distances $r$ according to a power law $\\sim r^{-a}$. Working within the frames of continuous chain model and applying the direct polymer renormalization scheme, we obtain the values of critical exponents governing the scaling of probabilities of loop formation with various positions along the chain as function of loops length. Our results quantitatively reveal that the presence of structural defects in environment decreases the probability of loop formation in polymer macromolecules.

  13. Tubulin in vitro, in vivo and in silico 

    E-Print Network [OSTI]

    Mershin, Andreas

    2005-02-17

    ACCUMULATION IN DROSOPHILA MUSHROOM BODY NEURONS RESULTS IN NEUROPLASTICITY IMPAIRMENT ............. 43 3.1 Introduction.............................................................................................. 43 3.2 Drosophila................................................................................... 6 2 Schematic of Quantum Teleportation of Dipole States.................................. 39 3 An XOR (exclusive-OR) Logic Gate............................................................. 40 4 Fly Mushroom Bodies (MBs...

  14. Photoreactivation in bacteria and in skin

    SciTech Connect (OSTI)

    Sutherland, B M

    1980-01-01

    In many procaryotic and eucaryotic cells, photoreactivating enzyme mediates light-dependent repair of uv-induced damage; the enzyme binds to a pyrimidine dimer in DNA, and, on absorption of a photon (300 to 600 nm), specifically monomerizes the dimer, thus repairing the DNA. Photoreactivating enzyme has been found in human tissues and human cells in culture can photoreactivate cellular dimers, and can mediate photoreactivation of Herpes (human fibroblasts) and Epstein-Barr virus (human leukocytes). Measurements of pyrimidine dimer formation and repair in human skin indicate that detectable numbers of dimers are formed at 1 minimal erythemal dose, that the dimiers are rapidly removed in skin kept in the absence of light, and they are more rapidly removed when the skin is exposed to visible light. Whether this apparent photorecovery is true, enzymatic photoreactivation is yet to be determined.

  15. THE MASSIVE SATELLITE POPULATION OF MILKY-WAY-SIZED GALAXIES

    SciTech Connect (OSTI)

    Rodriguez-Puebla, Aldo; Avila-Reese, Vladimir; Drory, Niv, E-mail: apuebla@astro.unam.mx [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A. P. 70-264, 04510 Mexico, DF (Mexico)

    2013-08-20

    Several occupational distributions for satellite galaxies more massive than m{sub *} Almost-Equal-To 4 Multiplication-Sign 10{sup 7} M{sub Sun} around Milky-Way (MW)-sized hosts are presented and used to predict the internal dynamics of these satellites as a function of m{sub *}. For the analysis, a large galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with currently available observations, namely the galaxy stellar mass function decomposed into centrals and satellites, and the two-point correlation functions at different masses. We find that 6.6% of MW-sized galaxies host two satellites in the mass range of the Small and Large Magellanic Clouds (SMC and LMC, respectively). The probabilities of the MW-sized galaxies having one satellite equal to or larger than the LMC, two satellites equal to or larger than the SMC, or three satellites equal to or larger than Sagittarius (Sgr) are Almost-Equal-To 0.26, 0.14, and 0.14, respectively. The cumulative satellite mass function of the MW, N{sub s} ({>=}m{sub *}) , down to the mass of the Fornax dwarf is within the 1{sigma} distribution of all the MW-sized galaxies. We find that MW-sized hosts with three satellites more massive than Sgr (as the MW) are among the most common cases. However, the most and second most massive satellites in these systems are smaller than the LMC and SMC by roughly 0.7 and 0.8 dex, respectively. We conclude that the distribution N{sub s} ({>=}m{sub *}) for MW-sized galaxies is quite broad, the particular case of the MW being of low frequency but not an outlier. The halo mass of MW-sized galaxies correlates only weakly with N{sub s} ({>=}m{sub *}). Then, it is not possible to accurately determine the MW halo mass by means of its N{sub s} ({>=}m{sub *}); from our catalog, we constrain a lower limit of 1.38 Multiplication-Sign 10{sup 12} M{sub Sun} at the 1{sigma} level. Our analysis strongly suggests that the abundance of massive subhalos should agree with the abundance of massive satellites in all MW-sized hosts, i.e., there is not a missing (massive) satellite problem for the {Lambda}CDM cosmology. However, we confirm that the maximum circular velocity, v{sub max}, of the subhalos of satellites smaller than m{sub *} {approx} 10{sup 8} M{sub Sun} is systematically larger than the v{sub max} inferred from current observational studies of the MW bright dwarf satellites; different from previous works, this conclusion is based on an analysis of the overall population of MW-sized galaxies. Some pieces of evidence suggest that the issue could refer only to satellite dwarfs but not to central dwarfs, then environmental processes associated with dwarfs inside host halos combined with supernova-driven core expansion should be on the basis of the lowering of v{sub max}.

  16. Electromagnetic Wave Dynamics in

    E-Print Network [OSTI]

    Kaiser, Robin

    Mesoscopic Electromagnetic Wave Dynamics in Ultracold Atomic Gases Robin Kaiser and Mark D. Havey Mesoscopic Electromagnetic Wave Dynamics in Ultracold Atomic Gases #12;39 E xperimental developments permit in the transport proper- ties of electromagnetic radiation in strongly scattering random media. Even in weakly

  17. Graduate Studies in Education

    E-Print Network [OSTI]

    , early childhood education, and curriculum and instruction. Beyond the master's degree, Furman offers and skills in a real­world setting. Early Childhood Education Designed to add endorsement in early childhood in the education core and 18 credits in early childhood courses--concluding in the master's seminar. The program

  18. CP violation in SUSY

    E-Print Network [OSTI]

    S. Kraml

    2007-10-26

    CP violation in supersymmetric models is reviewd with focus on explicit CP violation in the MSSM. The topics covered in particular are CP-mixing in the Higgs sector and its measurement at the LHC, CP-odd observables in the gaugino sector at the ILC, EDM constraints, and the neutralino relic density.

  19. Curriculum development in Informatics in Lithuania

    E-Print Network [OSTI]

    Gilbert, D.

    Gilbert,D. Innovations in Teaching of Computing 2: Imporving the Quality of Teaching and Learning. Editor M Smith pp ch.5 43-50

  20. Living in Liminality: Chinese Migrancy in Ghana

    E-Print Network [OSTI]

    Ho, Conal Guan-Yow

    2012-01-01

    to early fifties, from Dalian, China. Married. Husband andcontainer to arrive from Dalian, China. Once the containercareers. One was a woman from Dalian, a major port city in

  1. Statistics in Excel

    E-Print Network [OSTI]

    Dave

    2012-03-25

    Statistics in Excel. 1. Type the measurement data into consecutive cells in Excel. NOTE: they do not need to be in one column, but the cells should be adjacent.

  2. Shakespeare Studies in China

    E-Print Network [OSTI]

    Meng, Hui

    2012-05-31

    , the characteristic of Shakespeare studies in China is closely associated with the political and cultural situation of the time. This thesis chronicles and analyzes noteworthy scholarship of Shakespeare studies in China, especially since the 1990s, in terms...

  3. PCs in Business Environment

    E-Print Network [OSTI]

    Colak, Mijo Todor

    1994-07-29

    "PCs in Business Environment" is a project that contains two parts. First part is a real life application developed for Nordic Meat Inc. a small food - manufacturer in the KC area, developed in MS Excel 5.0 spreadsheet ...

  4. Entrepreneurialship Considerations in

    E-Print Network [OSTI]

    .S. Department of Energy ENERGY SOURCES cont. · Hydrogen · Fuel Cells · Efficiency and Conservation #12 economy ­ Increase in carbon intensity ­ Decline in efficiency of CO2 sinks on land and in oceans

  5. Bacteria in shear flow

    E-Print Network [OSTI]

    Marcos, Ph.D. Massachusetts Institute of Technology

    2011-01-01

    Bacteria are ubiquitous and play a critical role in many contexts. Their environment is nearly always dynamic due to the prevalence of fluid flow: creeping flow in soil, highly sheared flow in bodily conduits, and turbulent ...

  6. Ontology evolution in physics 

    E-Print Network [OSTI]

    Chan, Michael

    2013-07-02

    With the advent of reasoning problems in dynamic environments, there is an increasing need for automated reasoning systems to automatically adapt to unexpected changes in representations. In particular, the automation ...

  7. Willows in the Spring

    E-Print Network [OSTI]

    Hill, DaMaris B.

    2012-05-31

    gestational period of adolescence. It fictionalizes the oppressions and opportunities that emerged as a result of the Women's Suffrage Movement in the United States. Inspired by the glorious achievements of women in Kansas' history, Willows in the Spring is a...

  8. Charmonium in Hot Medium 

    E-Print Network [OSTI]

    Zhao, Xingbo

    2012-02-14

    We investigate charmonium production in the hot medium created by heavy-ion collisions by setting up a framework in which in-medium charmonium properties are constrained by thermal lattice QCD (lQCD) and subsequently ...

  9. Feed-in-Tariff

    Broader source: Energy.gov [DOE]

    Note: In August of 2013 the Hawaii Public Utility Commission (PUC) initiated an investigation into the Feed-In-Tariff Program in Docket No. 2013-0194. On December 5th, 2014 the Hawaii PUC issued...

  10. Essays in organizational economics

    E-Print Network [OSTI]

    Powell, Michael Leslie

    2011-01-01

    The first chapter examines the interaction of heterogeneous firms in a competitive market in which firms motivate their workers using relational incentive contracts. In the steady-state rational-expectations equilibrium, ...

  11. Representation in Municipal Government

    E-Print Network [OSTI]

    Warshaw, Christopher

    Municipal governments play a vital role in American democracy, as well as in governments around the world. Despite this, little is known about the degree to which cities are responsive to the views of their citizens. In ...

  12. Representation in Municipal Government

    E-Print Network [OSTI]

    Tausanovitch, Chris

    2014-07-30

    Municipal governments play a vital role in American democracy, as well as in governments around the world. Despite this, little is known about the degree to which cities are responsive to the views of their citizens. In ...

  13. Foreign Deities in Egypt

    E-Print Network [OSTI]

    Zivie-Coche, Christiane

    2011-01-01

    fig. 211. ) Foreign Deities in Egypt, Zivie-Coche, UEE 2011god Hauron and his cult in Egypt. Göttinger Miszellen 107,2011, Foreign Deities in Egypt. UEE. Full Citation: Zivie-

  14. TRANSFORMATION TOUGHENING IN CERAMICS

    E-Print Network [OSTI]

    Evans, A.G.

    2013-01-01

    Preprint ~. Submitted to Advances in Ceramics TRANSFORMATIONTOUGHENING IN CERAMICS A.G. Evans, D.B. Marshall, and N.H.TRANSFORMATION TOUGHENING IN CERAMICS by Ao Go Evans, D. Be

  15. Toponym Resolution in Text 

    E-Print Network [OSTI]

    Leidner, Jochen Lothar

    2007-06-26

    Background. In the area of Geographic Information Systems (GIS), a shared discipline between informatics and geography, the term geo-parsing is used to describe the process of identifying names in text, which in computational ...

  16. Corruption in Developing Countries

    E-Print Network [OSTI]

    Olken, Benjamin A.

    Recent years have seen a remarkable expansion in economists' ability to measure corruption. This in turn has led to a new generation of well-identified, microeconomic studies. We review the evidence on corruption in ...

  17. Symmetries in physics

    E-Print Network [OSTI]

    Roelof Bijker

    2005-09-02

    The concept of symmetries in physics is briefly reviewed. In the first part of these lecture notes, some of the basic mathematical tools needed for the understanding of symmetries in nature are presented, namely group theory, Lie groups and Lie algebras, and Noether's theorem. In the second part, some applications of symmetries in physics are discussed, ranging from isospin and flavor symmetry to more recent developments involving the interacting boson model and its extension to supersymmetries in nuclear physics.

  18. Fraud Detection in Healthcare

    SciTech Connect (OSTI)

    Chandola, Varun; Schryver, Jack C; Sukumar, Sreenivas R

    2015-01-01

    We discuss the problem of fraud detection in healthcare in this chapter. Given the recent scrutiny of the ineciencies in the US healthcare system, identifying fraud has been on the forefront of the eorts towards reducing the healthcare costs. In this chapter we will focus on understanding the issue of healthcare fraud in detail, and review methods that have been proposed in the literature to combat this issue using data driven approach.

  19. Essays in empirical microeconomics

    E-Print Network [OSTI]

    Tang, Yuan Emily

    2007-01-01

    We find that charter school performance in San Diego varieswe find that charter school performance is indistinguishableWe find that charter school performance in San Diego varies

  20. Top quark in theory

    E-Print Network [OSTI]

    Eric Laenen

    2008-09-18

    I review how the top quark is embedded in the Standard Model and some its proposed extensions, and how it manifests itself in various hadron collider signals.

  1. Essays in Development Economics

    E-Print Network [OSTI]

    Bazzi, Samuel Ali

    are weak,” Review of Economics and Statistics, 2004, 86,Essays in Development Economics A dissertation submitted indegree Doctor of Philosophy in Economics by Samuel Ali Bazzi

  2. Acid Violence in Pakistan

    E-Print Network [OSTI]

    Zia, Taiba

    2013-01-01

    Jordan. “Acid Attacks: Bangladesh’s Efforts to Stop thesubcontinent, especially in Bangladesh and Pakistan, and inon acid crimes in Bangladesh, for instance). Reliable data

  3. article in press

    E-Print Network [OSTI]

    2005-01-31

    United States alone (Russo, 2004). In response, several measures ..... where dr and dc are the death rates of the rats and the birds respectively. In the following,.

  4. Nucleosynthesis in barium stars

    E-Print Network [OSTI]

    Trimble, V; Trimble, V

    1984-01-01

    problem of apparent nucleosynthesis in barium stars, thoughSE24 9JF. Astronomy Nucleosynthesis in barium stars fromopportunity to see that nucleosynthesis really is taking

  5. UF in Osnabrck Understanding Engineering in Europe

    E-Print Network [OSTI]

    Hill, Jeffrey E.

    will: 1) be introduced to various industries in Germany with the engineering and energy use highlighted; 2) learn cultural and historical information about Germany and the European Union; 3) learn how the chance to climb a 100 meter tall wind generator tower! About the Location Osnabrück is located in Lower

  6. Metacognition in Animals Metacognition in animals

    E-Print Network [OSTI]

    Indiana University

    , first-order explanations are representations about stimuli in the world (i.e., beliefs about the world, an assessment of what is `lost' (in terms of existing methods and data) necessitates the development of new, innovative methods for metacognition. Development of new methods may prompt the establishment of new

  7. Trends in stationary energy

    SciTech Connect (OSTI)

    2013-04-01

    Trends in Stationary Energy Lunch Presentation for the 2013 Building Technologies Office's Program Peer Review

  8. study programs in mathematics

    E-Print Network [OSTI]

    ?umer, Slobodan

    study programs in m mathematics #12;#12;3 CONTENTS 5 Introduction 7 Mathematics at the University of Ljubljana 9 Department of Mathematics information page Academic study program in Mathematics Academic study program in Financial Mathematics Single cycle master's study program in Mathematics education

  9. RESEARCH IN PARTICLE PHYSICS

    SciTech Connect (OSTI)

    Kearns, Edward

    2013-07-12

    This is the final report for the Department of Energy Grant to Principal Investigators in Experimental and Theoretical Particle Physics at Boston University. The research performed was in the Energy Frontier at the LHC, the Intensity Frontier at Super-Kamiokande and T2K, the Cosmic Frontier and detector R&D in dark matter detector development, and in particle theory.

  10. Reading context in design

    E-Print Network [OSTI]

    Agrawal, Vivek

    1993-01-01

    This study explores how, in the process of design, the reading of an existing order in the organizing features of a setting potentiates form. For this purpose, a design exercise on a site in the city of Jaipur in India has ...

  11. Problems in Engineering and

    E-Print Network [OSTI]

    Eagar, Thomas W.

    Problems in Engineering and Science Education Why Do We Have a Weakness in Materials Synthesis, Materials Science and Engineering in the 1990s: Maintaining Competitiveness in the Age of Materials science and engi- neering alone; it is symptomatic of the way we teach all science and engineering. We

  12. CORRELATIONS IN STOCHASTIC SYSTEMS

    E-Print Network [OSTI]

    Karney, Charles

    LONG-TIME CORRELATIONS IN STOCHASTIC SYSTEMS Charles F. F. Karney Plasma Physics Laboratory in understand- ing the motion in Hamiltonian systems when phase space is divided into stochastic and integrable in the stochastic sea when there is a small island present. The results show that the particle can be stuck close

  13. Gilgit in Ancient Times

    E-Print Network [OSTI]

    Prakash, Buddha

    1970-11-20

    , the younger brother of the king of Bukhara reached the Chinese court, in 727, the king of Kesh sent an envoy. there, in 728, the kings of Wakhan and Maimargh, in 729, thoseof Wakhan and Khuttal, in7 30, that of Maimargh, in 73 I, that of Samarkand and... in Central Asia. In 739 one of their generals cooperated with the kings of Kesh and Samarkand to imprison Su-Iu's son T'ou-ho-sien near Tukmak whereas another army joined hands with the king of Ferghanah for suppressing the Kagan of the Black tribes...

  14. Nuclear spirals in galaxies

    E-Print Network [OSTI]

    Witold Maciejewski

    2006-11-08

    Recent high-resolution observations indicate that nuclear spirals are often present in the innermost few hundred parsecs of disc galaxies. My models show that nuclear spirals form naturally as a gas response to non-axisymmetry in the gravitational potential. Some nuclear spirals take the form of spiral shocks, resulting in streaming motions in the gas, and in inflow comparable to the accretion rates needed to power local Active Galactic Nuclei. Recently streaming motions of amplitude expected from the models have been observed in nuclear spirals, confirming the role of nuclear spirals in feeding of the central massive black holes.

  15. Investments in children in developing countries

    E-Print Network [OSTI]

    Nelson, Leah Kyung

    2012-01-01

    3.2. Summary Statistics for India . . . . . . . . . . . .Table 3.2. Summary Statistics for India All Male Female Meanstatistics for mother characteristics are presented in Appendix Table 2 for India (

  16. Statement of In??s Triay

    Office of Environmental Management (EM)

    SNM and SNF. EM cleanup objectives will continue to be advanced in FY 2011 by the infusion of 6 billion from the American Recovery and Reinvestment Act of 2009 (Recovery Act)....

  17. Energy Efficiency in Buildings in Switzerland 

    E-Print Network [OSTI]

    Chuard, J.

    2004-01-01

    In Switzerland, a culture for low energy concepts is established. The procedure for quality assurance during design, elaboration, construction, and acceptance phases is based on detailed technical checklists. These procedures are similar...

  18. Dihadron fragmentation: in vacuum and in matter

    E-Print Network [OSTI]

    A. Majumder

    2005-03-08

    Two particle correlations within a single jet produced in deeply inelastic scattering (DIS) off a large nucleus as well as in heavy-ion collisions are explored. This is performed within the framework of the medium modified dihadron fragmentation functions. The modification occurs due to gluon bremsstrahlung induced by multiple scattering. The modified fragmentation functions for dihadrons are found to follow closely that of single hadrons leading to a weak nuclear suppression of their ratios as measured by HERMES in DIS experiments. Meanwhile, a moderate medium enhancement of the near-side correlation of two high $p_T$ hadrons is found in central heavy-ion collisions, partially due to trigger bias caused by the competition between parton energy loss and the initial Cronin effect.

  19. Films in the Archive: Hollywood in Detroit

    E-Print Network [OSTI]

    Shell, Hanna Rose

    The Prelinger Archives, a collection of over 60,000 so-called ephemeral films, approximately 6,500 of which are freely available online for viewing and public download, is an amazing resource for research and teaching in ...

  20. Quantum control in spintronics

    E-Print Network [OSTI]

    A. Ardavan; G. A. D. Briggs

    2011-02-08

    Superposition and entanglement are uniquely quantum phenomena. Superposition incorporates a phase which contains information surpassing any classical mixture. Entanglement offers correlations between measurements in quantum systems that are stronger than any which would be possible classically. These give quantum computing its spectacular potential, but the implications extend far beyond quantum information processing. Early applications may be found in entanglement enhanced sensing and metrology. Quantum spins in condensed matter offer promising candidates for investigating and exploiting superposition and entanglement, and enormous progress is being made in quantum control of such systems. In GaAs, individual electron spins can be manipulated and measured, and singlet-triplet states can be controlled in double-dot structures. In silicon, individual electron spins can be detected by ionisation of phosphorous donors, and information can be transferred from electron spins to nuclear spins to provide long memory times. Electron and nuclear spins can be manipulated in nitrogen atoms incarcerated in fullerene molecules, which in turn can be assembled in ordered arrays. Spin states of charged nitrogen vacancy centres in diamond can be manipulated and read optically. Collective spin states in a range of materials systems offer scope for holographic storage of information. Conditions are now excellent for implementing superposition and entanglement in spintronic devices, thereby opening up a new era of quantum technologies.

  1. Dust Measurements in Tokamaks

    SciTech Connect (OSTI)

    Rudakov, D; Yu, J; Boedo, J; Hollmann, E; Krasheninnikov, S; Moyer, R; Muller, S; Yu, A; Rosenberg, M; Smirnov, R; West, W; Boivin, R; Bray, B; Brooks, N; Hyatt, A; Wong, C; Fenstermacher, M; Groth, M; Lasnier, C; McLean, A; Stangeby, P; Ratynskaia, S; Roquemore, A; Skinner, C; Solomon, W M

    2008-04-23

    Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering resolves size of particles between 0.16-1.6 {micro}m in diameter; the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast-framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in 2D with a single camera or 3D using multiple cameras, but determination of particle size is problematic. In order to calibrate diagnostics and benchmark dust dynamics modeling, pre-characterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase of carbon atomic, C2 dimer, and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.

  2. Iron efficiency in sorghum 

    E-Print Network [OSTI]

    Esty, James Craig

    1979-01-01

    . DeKoch (28) indicated that the total amount of Fe in the roots of plants bears little relation to chlorosis, as roots of chlorotic plants may contain a higher percentage of Fe than roots of healthy plants. Fe was internally inactivated in soybeans...) developed a technique to de- termine Fe efficiency in plants, they stated that some control of pH was needed in the growth medium and they + accomplished this by using NO 3 nitrogen and NH 4 nitrogen in nutrient solutions. A decrease in pH of the growth...

  3. Heat transmission in Relativity

    E-Print Network [OSTI]

    A. Brotas; J. C. Fernandes

    2003-07-16

    The simultaneous study of deformation and heat transmission in a bar was ignored for about 150 years. The traditional Fourier equation just allows to study the evolution of temperature in a undeformable bar. The search for its relativistic variant is a task which must fail because in Relativity there are no undeformable bars. Rigid bodies, in the sense as rigid as possible, are deformables. In this work we show how to write in Relativity the system of equations necessary to study simultaneously deformation and temperature evolution along a rigid bar.

  4. Nuclear Masses in Astrophysics

    E-Print Network [OSTI]

    Christine Weber; Klaus Blaum; Hendrik Schatz

    2008-12-09

    Among all nuclear ground-state properties, atomic masses are highly specific for each particular combination of N and Z and the data obtained apply to a variety of physics topics. One of the most crucial questions to be addressed in mass spectrometry of unstable radionuclides is the one of understanding the processes of element formation in the Universe. To this end, accurate atomic mass values of a large number of exotic nuclei participating in nucleosynthesis are among the key input data in large-scale reaction network calculations. In this paper, a review on the latest achievements in mass spectrometry for nuclear astrophysics is given.

  5. Fire Size in Tunnels 

    E-Print Network [OSTI]

    Carvel, Ricky O

    In recent years, a number of high profile accidental fires have occurred in several road and rail tunnels throughout the world. Many of these fires grew rapidly to catastrophic size and claimed many lives. The processes ...

  6. Locative Inversion In Cantonese

    E-Print Network [OSTI]

    Mok, Sui-Sang

    1992-01-01

    This paper proposes that locative inversion is a widespread syntactic process in Cantonese. The sentence-initial locative phrases in the Locative Inversion sentences are argued to be subjects which come from the postverbal complement position...

  7. In Her Nature

    E-Print Network [OSTI]

    Scribner, Rachel

    2014-05-31

    /, includes nine oil paintings displayed on the walls of the gallery. The paintings are based on structures existing in nature, but suggest an interior landscape and personal expression. Ranging in size and orientation, the paintings compromise...

  8. LPG in Venezuela

    SciTech Connect (OSTI)

    Romero, O.

    1986-01-01

    The use of LPG for domestic consumption in Venezuela began in late 1929 when LPG was imported in lots of 500 cylinders. These cylinders were then returned to the U.S. for refilling. Total consumption at that time was some 40M/sup 3/ (250 barrels) per year and by 1937 had grown to some 540M/sup 3/ (3,400 barrels) per year. Local production of LPG from gas began in the mid thirties with a small cooling plant in the Mene Grande Field in the Lake Maracaibo area, the first field to produce oil in Venezuela (1914). This plant produced gasoline for a refinery and some of the first LPG used in Venezuela for domestic consumption. The capacity of this plant was insufficient to satisfy the growing demand for LPG which was supplied from refinery production until the development of the natural gas processing industry. At the present time, Venezuelan refineries are net consumers of LPG.

  9. Random Walks in Applications

    E-Print Network [OSTI]

    Whitt, Ward

    section we discuss the engineering significance of the queueing model and the (heavy­traffic) stochastic prices, the Kolmogorov­Smirnov test statistic and a queueing model for a buffer in a switch. In the final

  10. In situ measurement system

    DOE Patents [OSTI]

    Lord, D.E.

    1980-11-24

    A multipurpose in situ underground measurement system comprising a plurality of long electrical resistance elements in the form of rigid reinforcing bars, each having an open loop hairpin configuration of shorter length than the other resistance elements. The resistance elements are arranged in pairs in a unitized structure, and grouted in place in the underground volume. Measurement means are provided for obtaining for each pair the electrical resistance of each element and the difference in electrical resistance of the paired elements, which difference values may be used in analytical methods involving resistance as a function of temperature. A scanner means sequentially connects the resistance-measuring apparatus to each individual pair of elements. A source of heating current is also selectively connectable for heating the elements to an initial predetermined temperature prior to electrical resistance measurements when used as an anemometer.

  11. Allies in Sport Organizations 

    E-Print Network [OSTI]

    Melton, Elizabeth

    2012-10-19

    Employee support is a key factor in creating more welcoming and accepting work environments for lesbian, gay, bisexual, and transgender (LGBT) individuals in sport. As such, organizations need to understand what factors ...

  12. Nouns In Tutelo

    E-Print Network [OSTI]

    Oliverio, Giulia R. M.

    1992-01-01

    My purpose in this paper is to sketch the different features of noun grammar in Tutelo, a Siouan language of the East. A description of derivational processes will not be attempted here though as much more study is required ...

  13. Cutaneous leishmaniasis in Pakistan

    E-Print Network [OSTI]

    Khan, Shiraz Jamal; Muneeb, Syed

    2005-01-01

    from various regions of Pakistan. J Coll Physicians SurgR. Cutaneous Leishmaniasis in Pakistan. Int J Dermatol. 2001cutaneous leishmaniasis in Pakistan: a 6-year study. Int J

  14. Essays in financial economics

    E-Print Network [OSTI]

    Edmans, Alex

    2007-01-01

    This thesis consists of three essays in financial economics. Chapter 1 is entitled "Inside Debt." Existing theories advocate the use of cash and equity in executive compensation. However, recent empirical studies have ...

  15. Essays in empirical finance

    E-Print Network [OSTI]

    Kumar, Pavithra Kamakshi

    2008-01-01

    The first chapter in my thesis investigates the association between selected hedge fund characteristics and persistence in performance over time. Analyzing TASS data from 1996-2006, I observe a positive correlation between ...

  16. Essays in development economics

    E-Print Network [OSTI]

    Keniston, Daniel Eben

    2011-01-01

    Chapter 1 looks at the empirical estimation of the welfare impacts of bargaining. Bargaining for retail goods is common in developing countries, but rare in the developed world. The welfare implications of this difference ...

  17. The subjunctive in Spanish

    E-Print Network [OSTI]

    Solano, J. Miguel

    1980-01-01

    The various analyses for the subjunctive in Spanish that have been proposed can be classified into two major categories: syntactic and semantic. Syntactic analyses consist mainly of classifications of instances in which the subjunctive must be used...

  18. Essays in capital markets

    E-Print Network [OSTI]

    Papanikolaou, Dimitris, Ph. D. Massachusetts Institute of Technology

    2007-01-01

    In the first chapter, I provide evidence that investment-specific technological change is a source of systematic risk. In contrast to neutral productivity shocks, the economy needs to invest to realize the benefits of ...

  19. Advertising in computer games

    E-Print Network [OSTI]

    Vedrashko, Ilya

    2006-01-01

    This paper suggests advertisers should experiment with in-game advertising to gain skills that could become vital in the near future. It compiles, arranges and analyzes the existing body of academic and industry knowledge ...

  20. URANIUM IN ALKALINE ROCKS

    E-Print Network [OSTI]

    Murphy, M.

    2011-01-01

    1962. "Diatremes and Uranium Deposits in the Hopi Buttes,H. , 1970. "Low-Grade Uranium Deposits in Agpaitic NephelineL. Torkild, 1974B. "The Uranium Deposit at Kvanefjeld, The

  1. Credit derivatives in Brazil

    E-Print Network [OSTI]

    Rüther, Henrique

    2007-01-01

    The amounts outstanding of credit derivatives have grown exponentially over the past years, and these financial intruments that allow market participants to trade credit risk have become very popular in Europe and in the ...

  2. Endocytosis in filamentous fungi 

    E-Print Network [OSTI]

    Kalkman, Edward R I C

    2007-01-01

    Endocytosis is little understood in filamentous fungi. For some time it has been controversial as to whether endocytosis occurs in filamentous fungi. A comparative genomics analysis between Saccharomyces cerevisiae and ...

  3. Federal participation in LEED

    SciTech Connect (OSTI)

    Payne, Christopher; Dyer, Beverly

    2004-11-10

    The federal government has been an active participant in the development and use of USGBC's Leadership in Energy & Environmental Design Green Building Rating System (LEED). This paper presents a review of this participation and some expectations for ongoing partnership.

  4. Energy Refits in Philadelphia

    Broader source: Energy.gov [DOE]

    The Greater Philadelphia region's historic buildings and homes are among the most significant in American history, but they predate modern energy-efficient designs by centuries. In fact, some...

  5. Scheduling in Multiprocess Systems

    E-Print Network [OSTI]

    Dou, Ji Adam

    2011-01-01

    in the lifetime of the WSN. As flash-based devices becomean attached battery. Traditional WSN data collection and in-PRESTO [79] is a two-tier WSN system which makes use of

  6. HRM in the USA

    E-Print Network [OSTI]

    Strauss, George

    1991-01-01

    Tower 8-2-91 page 1 HRM in the USA George Strauss* This is aHuman Resources Management (HRM) in the United States duringhuman resources management (HRM) during the late 1970s and

  7. Energy Use in Manufacturing

    Reports and Publications (EIA)

    2006-01-01

    This report addresses both manufacturing energy consumption and characteristics of the manufacturing economy related to energy consumption. In addition, special sections on fuel switching capacity and energy-management activities between 1998 and 2002 are also featured in this report.

  8. Transport in granular systems

    E-Print Network [OSTI]

    Wendell, Dawn M. (Dawn Marie), 1983-

    2011-01-01

    There are many situations in which a continuum view of granular systems does not fully capture the relevant mechanics. In order for engineers to be able to design systems for transporting granular materials, there needs ...

  9. Safety in Buildings 

    E-Print Network [OSTI]

    Hutcheon, N. B.

    Building codes are essentially sets of safety regulations in respect of structure, fire, and health. They were originally developed in response to frequently demonstrated hazards of structural collapse, catastrophic fires, ...

  10. Specific light in sculpture

    E-Print Network [OSTI]

    Powell, John William

    1989-01-01

    Specific light is defined as light from artificial or altered natural sources. The use and manipulation of light in three dimensional sculptural work is discussed in an historic and contemporary context. The author's work ...

  11. Muslim Leadership in America 

    E-Print Network [OSTI]

    Mobeen, Noor 1982-

    2012-11-27

    Leadership has been a foundational component of any society, religion, culture, and human development. The purpose of this study was six fold: to examine the concept of leadership in Muslim communities in America, to observe the first...

  12. Essays in Public Economics

    E-Print Network [OSTI]

    Lee, Insook

    2013-01-01

    in the taxation, since each taxpayer can take advantage ofverify the true amount of taxpayer’s earnings, unlike theirutility of risk-averse taxpayers from an increment in the

  13. Three essays in macroeconomics

    E-Print Network [OSTI]

    Auer, Raphael Anton Maximilian Peter Gabriel

    2006-01-01

    This thesis is a collection of three essays on international trade and economic growth. Chapter 1 analyzes the dynamic gains from trade in a Hecksher-Ohlin economy with endogenous factor accumulation. In a framework where ...

  14. Electrotechnologies in Process Industries 

    E-Print Network [OSTI]

    Amarnath, K. R.

    1989-01-01

    applications of innovative electrotechnologies in these sectors. APPLICATIONS Electricity is predominantly used in three ways in process industries: 1. Motor Drives 2. Process Heating 3. Electrochemical Processes Motor drives are mainly used in prime..., infrared, and ultraviolet heating have found a variety of applications, and more are under development. ElectrOChemical processes for separation and synthesis (such as Chlor-Alkali production) are significant users of electricity. New processes...

  15. Partnership in Computational Science

    SciTech Connect (OSTI)

    Huray, Paul G.

    1999-02-24

    This is the final report for the "Partnership in Computational Science" (PICS) award in an amount of $500,000 for the period January 1, 1993 through December 31, 1993. A copy of the proposal with its budget is attached as Appendix A. This report first describes the consequent significance of the DOE award in building infrastructure of high performance computing in the Southeast and then describes the work accomplished under this grant and a list of publications resulting from it.

  16. Spectral Functions in QFT

    E-Print Network [OSTI]

    Pablo Pisani

    2015-05-16

    We present a pedagogical exposition of some applications of functional methods in quantum field theory: we use heat-kernel and zeta-function techniques to study the Casimir effect, the pair production in strong electric fields, quantum fields at finite temperature and beta-functions for a self-interacting scalar field, QED and pure Yang-Mills theories. The more recent application to the UV/IR mixing phenomenon in noncommutative theories is also discussed in this framework.

  17. Motion in Quantum Gravity

    E-Print Network [OSTI]

    Karim Noui

    2010-03-31

    We tackle the question of motion in Quantum Gravity: what does motion mean at the Planck scale? Although we are still far from a complete answer we consider here a toy model in which the problem can be formulated and resolved precisely. The setting of the toy model is three dimensional Euclidean gravity. Before studying the model in detail, we argue that Loop Quantum Gravity may provide a very useful approach when discussing the question of motion in Quantum Gravity.

  18. article in press

    E-Print Network [OSTI]

    2007-11-28

    Nov 28, 2007 ... Please cite this article in press as: R. Liu et al., Bifurcation analysis of a plant–

  19. Electroluminescence in photovoltaic cell

    E-Print Network [OSTI]

    Petraglia, Antonio; 10.1088/0031-9120/46/5/F01

    2011-01-01

    Here we propose two methods to get electroluminescence images from photovoltaic cells in a school or home lab.

  20. Breakfast in a Hurry. 

    E-Print Network [OSTI]

    Reasonover, Frances L.

    1980-01-01

    reconstituted frozen juice or dry powder ed fruit drin k mix in a covered container in the refrigerator with in easy reach. Applesauce can be used directly from the con tainer. Buy applesauce in a jar for easy serving and storage. Wash apples and store... and toppings. Quick toppings that add variety are brown sugar, peanut butter and honey, jam, jelly, preserves and fruits such as applesauce, bananas, peaches, strawberries, blueberries and dried fruits. Nuts also may be used as toppings. Beverages ? Use...

  1. Optimization in Networks

    E-Print Network [OSTI]

    Adilson E. Motter; Zoltan Toroczkai

    2007-07-07

    The recent surge in the network modeling of complex systems has set the stage for a new era in the study of fundamental and applied aspects of optimization in collective behavior. This Focus Issue presents an extended view of the state of the art in this field and includes articles from a large variety of domains where optimization manifests itself, including physical, biological, social, and technological networked systems.

  2. Women in STEM

    Broader source: Energy.gov [DOE]

    A page showcasing the great contributions of women in the energy sector and encouraging girls to continue studying STEM.

  3. Point specificity in acupuncture

    E-Print Network [OSTI]

    Choi, Emma M; Jiang, Fang; Longhurst, John C

    2012-01-01

    assessed heart rate variability (HRV) in 111 subjects afterand increased the high-frequency HRV index of cardiac vagal

  4. Innovation Concepts in Healthcare

    ScienceCinema (OSTI)

    None

    2011-04-25

    AbstractDemographic change and advances in medical science pose increased challenges to healthcare systems globally: The economic basis is aging and thus health is becoming more and more a productivity factor. At the same time, with today?s new communication possibilities the demand and expectations of effective medical treatment have been increased. This presentation will illustrate the need for the ?industrialization? of healthcare in order to achieve highest results at limited budgets. Thereby, industrialization is not meaning the medical treatment based on the assembly line approach. Rather it is to recognize the cost of medical care as an investment with respective expectations on the return of the investment. Innovations in imaging and pharmaceutical products as well as in processes - that lead to similar medical results, but with lower efforts - are keys in such scenarios.BiographyProf. Dr. Hermann Requardt, 54, is a member of the Managing Board of Siemens AG and Chief Executive Officer of the Healthcare Sector. In addition he is the CTO of Siemens AG and Head of Corporate Technology, the central research department at Siemens.After completing his studies in physics and philosophy at the Darmstadt University of Technology and Johann Wolfgang Goethe University in Frankfurt and receiving a doctorate in biophysics, he worked at the Institute of Aerospace Medicine at the German Aerospace Center.In 1984 he joined the Medical Technology Group of Siemens AG, where he was responsible for projects in the Magnetic Resonance (MR) division. He was appointed head of the division in 1995. From 2001 to 2006, as a member of the Executive Management of the Medical Solutions Group, he was responsible for several areas, including technological development.In 2006 he became a Member of the Siemens? Managing Board and head of Corporate Technology. He was additionally appointed as the Sector Healthcare CEO in 2008.Since 2006 he is an honorary professor in physics of the Johann Wolfgang Goethe University in Frankfurt.                                                                                

  5. Entanglement in quantum catastrophes

    E-Print Network [OSTI]

    Clive Emary; Neill Lambert; Tobias Brandes

    2005-03-17

    We classify entanglement singularities for various two-mode bosonic systems in terms of catastrophe theory. Employing an abstract phase-space representation, we obtain exact results in limiting cases for the entropy in cusp, butterfly, and two-dimensional catastrophes. We furthermore use numerical results to extract the scaling of the entropy with the non-linearity parameter, and discuss the role of mixing entropies in more complex systems.

  6. Innovation Concepts in Healthcare

    SciTech Connect (OSTI)

    2011-01-06

    AbstractDemographic change and advances in medical science pose increased challenges to healthcare systems globally: The economic basis is aging and thus health is becoming more and more a productivity factor. At the same time, with today’s new communication possibilities the demand and expectations of effective medical treatment have been increased. This presentation will illustrate the need for the “industrialization” of healthcare in order to achieve highest results at limited budgets. Thereby, industrialization is not meaning the medical treatment based on the assembly line approach. Rather it is to recognize the cost of medical care as an investment with respective expectations on the return of the investment. Innovations in imaging and pharmaceutical products as well as in processes - that lead to similar medical results, but with lower efforts - are keys in such scenarios.BiographyProf. Dr. Hermann Requardt, 54, is a member of the Managing Board of Siemens AG and Chief Executive Officer of the Healthcare Sector. In addition he is the CTO of Siemens AG and Head of Corporate Technology, the central research department at Siemens.After completing his studies in physics and philosophy at the Darmstadt University of Technology and Johann Wolfgang Goethe University in Frankfurt and receiving a doctorate in biophysics, he worked at the Institute of Aerospace Medicine at the German Aerospace Center.In 1984 he joined the Medical Technology Group of Siemens AG, where he was responsible for projects in the Magnetic Resonance (MR) division. He was appointed head of the division in 1995. From 2001 to 2006, as a member of the Executive Management of the Medical Solutions Group, he was responsible for several areas, including technological development.In 2006 he became a Member of the Siemens’ Managing Board and head of Corporate Technology. He was additionally appointed as the Sector Healthcare CEO in 2008.Since 2006 he is an honorary professor in physics of the Johann Wolfgang Goethe University in Frankfurt.                                                                                

  7. Materials in design 

    E-Print Network [OSTI]

    Perata, Alfredo Ferando

    1970-01-01

    gears so the alloy content has to be higher. Gear shape -17- $11 these considerations can be summarized in three reasons for selecting a terial. 1) The mechanical properties of the material selected had to satisfy the service requirements 2... of materials at the various temperatures encountered in service and during the process of manufacturing. He must know other properties such as resistance to corrosion in the expected environment and their rate of change in mechanical properties with time...

  8. Individual variation in cooperative behaviour in meerkats

    E-Print Network [OSTI]

    English, Sinéad

    2010-04-13

    foraging behaviour and vocalizations 92 7.1 Abstract 93 7.2 Introduction 93 7.3 Methods 97 7.3.1 Do adults modify their foraging behaviour in the presence of pups? 97 7.3.2 Do adults modify their vocalizations in the presence of pups? 99 7.3.3 What... depending on the environment (Luttbeg and Warner, 1999). There is increasing evidence, however, that behaviour may be constrained within individuals (Pigliucci, 2001), just as there are limits on other aspects of phenotypic plasticity (DeWitt et al., 1998...

  9. Outrigger in Scandinavia

    E-Print Network [OSTI]

    station in Poznan, Poland, in the 2009-2011 timeframe. SKA Square Kilometre Array. Australia or South diagnostics. Can we do better? The Westerbork array of 14 dishes, each 25 m in diameter sees nearby objects, Växjö, 9 June, 2008 LOFAR Low Frequency Array (10­240 MHz). Test station at Exloo operational 2004, full

  10. Outrigger in Scandinavia

    E-Print Network [OSTI]

    , 2008. Full- scale station in Poznan, Poland, in the 2009-2011 timeframe. SKA Square Kilometre Array? The Westerbork array of 14 dishes, each 25 m in diameter sees nearby objects emitting 1420.4 MHz (21 cm H of Warwick, UK, January 16, 2008 LOFAR Low Frequency Array (10­240 MHz). Test station at Exloo operational

  11. The cartel in retreat

    E-Print Network [OSTI]

    Adelman, Morris Albert

    1993-01-01

    In 1981, the price of oil was $34 in current dollars ($50 at 1992 price levels). The consensus was that it would keep rising toward the cost of synthetic crude oil or some such long-run ceiling. In fact, the cartel had ...

  12. Expert systems in transportation

    SciTech Connect (OSTI)

    O'Leary, K.P.

    1988-01-01

    The 5 papers in the report deal with the following areas: Knowledge representation and software selection for expert-systems design; Expert-system architecture for retaining-wall design; Development of expert-systems technology in the California Department of Transportation; Development of an expert system to assist in the interactive graphic transit system design process; Expert systems development for contingency transportation planing.

  13. Extinction curves in AGN

    E-Print Network [OSTI]

    B. Czerny

    2006-12-16

    The presence of the dust in the circumnuclear region strongly affects our view of the nucleus itself. The effect is strong in type 2 objects but weaker effect is likely to be present in type 1 objects as well. In these objects a correction to the observed optical/UV spectrum must be done in order to recover the intrinsic spectrum of a nucleus. The approach based on the extinction curve is convenient for that purpose so significant effort has been recently done in order to determine the extinction curve for the circumnuclear material. It seems clear that the circumnuclear dust is different from the average properties of the dust in the Interstellar Medium in our galaxy: the well known 2175 A feature is weak or absent in AGN nuclear dust, and the extinction curve at shorter wavelength does not seem to be rising as steeply. The circumnuclear dust is therefore more similar to SMC dust, or more likely, to the dust in very dense molecular clouds in our Galaxy. However, the exact shape of the extinction curve in the far UV is still a matter of debate, and various effects are difficult to disentangle.

  14. in Economics and Finance

    E-Print Network [OSTI]

    van der Torre, Leon

    Master's in Economics and Finance ­ #12;2 3 "A research-centred institution with a personal REASONS TO STUDY The Master's in Economics and Finance programme targets students wishing to obtain a comprehensive and rigorous education in Economics and Finance. It emphasizes the complementary nature

  15. Developments in Human Communication

    E-Print Network [OSTI]

    Thompson, Michael

    CMST 1B03 Developments in Human Communication: Part & Present Amanda Etches-Johnson Mills Research in Human Communication Session Outline 1. Finding Books Using MORRIS 2. Finding Journal Articles using: Developments in Human Communication What is MORRIS anyway? · MORRIS is McMaster's library catalogue · Shows

  16. Aging in community

    E-Print Network [OSTI]

    Fay, Justin (Justin Thomas)

    2008-01-01

    Baby Boomers are on the brink of retirement. According to U.S. Census Bureau projections, the number of people aged 65 and over will more than double in the coming decades, growing from 35 million in 2000 to 72 million in ...

  17. Emergent gravity in graphene

    E-Print Network [OSTI]

    M. A. Zubkov; G. E. Volovik

    2013-08-09

    We reconsider monolayer graphene in the presence of elastic deformations. It is described by the tight - binding model with varying hopping parameters. We demonstrate, that the fermionic quasiparticles propagate in the emergent 2D Weitzenbock geometry and in the presence of the emergent U(1) gauge field. Both emergent geometry and the gauge field are defined by the elastic deformation of graphene.

  18. Anaerobic Hydrocarbon Degradation in

    E-Print Network [OSTI]

    Bruns, Tom

    Anaerobic Hydrocarbon Degradation in Petroleum-Contaminated Harbor Sediments under Sulfate of iron(III) oxide to stimulate in- situ hydrocarbon degradation in anaerobic petroleum- contaminated did not stimulate anaerobic hydrocarbon oxidation. Exposure of the sediment to air [to reoxidize Fe

  19. In the Profession: Peer Review in Academic Publishing

    E-Print Network [OSTI]

    Bucholtz, M

    2010-01-01

    Robin Queen. 2007. In the profession: Academic publication.Barbara. 2009. In the profession: Choosing the right journaleng.sagepub.com In the Profession: Peer Review in Academic

  20. Shared Space vs. In-Unit Upgrades in Multifamily Buildings |...

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

    Shared Space vs. In-Unit Upgrades in Multifamily Buildings Shared Space vs. In-Unit Upgrades in Multifamily Buildings Better Buildings Neighborhood Program Multifamily Peer...

  1. Neutron inelastic scattering in natural Pb as a background in...

    Office of Scientific and Technical Information (OSTI)

    Neutron inelastic scattering in natural Pb as a background in neutrinoless double-beta decay experiments Citation Details In-Document Search Title: Neutron inelastic scattering in...

  2. Regulation and Moral Hazard in Forest Concessions in Brazil

    E-Print Network [OSTI]

    Balbinotto Neto, Giácomo; Tillmann, Eduardo A; Ratnieks, Ianes

    2012-01-01

    and Forest Concessions in Brazil. Planejamento e Políticaswelfare maximization in Brazil. Rio de Janeiro: IPEA, 1998.in Forest Concessions in Brazil Eduardo A. Tillmann MS.

  3. Substantial improvements in methyl ketone production in E. coli...

    Office of Scientific and Technical Information (OSTI)

    Substantial improvements in methyl ketone production in E. coli and insights on the pathway from in vitro studies Citation Details In-Document Search Title: Substantial...

  4. Childhood in Premodern China

    E-Print Network [OSTI]

    Dardess, John W.

    1991-03-01

    instruction.20 Hand in hand with the scholarly effort to repossess the antique program of primary instruction there also was set in motion a long series of concrete attempts to set up elementary schools in the here and now. These reforms did not, as a rule... or meditative study. The rest will not. Slight, but interesting differences among families arise in connection with the question of what to do about the young washouts. Huo T'ao's solution was, as far as I know, unusual in its enthusiasm for physical labor...

  5. Secular evolution in galaxies

    E-Print Network [OSTI]

    F. Combes

    2006-08-29

    New observations in favour of a significant role of secular evolution are reviewed: central star formation boosted in pseudo-bulge barred galaxies, relations between bulge and disk, evidence for rejuvenated bulges. Numerical simulations have shown that secular evolution can occur through a cycle of bar formation and destruction, in which the gas plays a major role. Since bars are weakened or destroyed in gaseous disks, the high frequency of bars observed today requires external cold gas accretion, to replenish the disk and allow a new bar formation. The rate of gas accretion from external filaments is compatible with what is observed in cosmological simulations.

  6. In Other News

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIn MemoriamIn OtherInInIn

  7. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningIn otherInInInIn

  8. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInIn otherInInIn

  9. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInInIn otherInIn

  10. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInInInIn otherIn

  11. Vortices In Circumstellar Disks

    E-Print Network [OSTI]

    Fred Adams; Richard Watkins

    1995-01-12

    We discuss the physics of vortices in the circumstellar disks associated with young stellar objects. We elucidate the basic physical properties of these localized storm systems. In particular, we consider point vortices, linear vortices, the effects of self-gravity, magnetic fields, and nonlinear aspects of the problem. We find that these vortices can exist in many different forms in the disks of young stellar objects and may play a role in the formation of binary companions and/or giant planets. Vortices may enhance giant planet formation via gravitational instability by allowing dust grains (heavy elements) to settle to the center on a short timescale; the gravitational instability itself is also enhanced because the vortices also create a larger local surface density in the disk. In addition, vortices can enhance energy dissipation in disks and thereby affect disk accretion. Finally, we consider the possibility that vortices of this type exist in molecular clouds and in the disk of the galaxy itself. On all of these size scales, vortices can produce long-lived structures which may correspond to observed structures in these systems.

  12. CORRECT TRACKING IN FFAGS.

    SciTech Connect (OSTI)

    BERG, J.S.

    2006-01-30

    Fixed field alternating gradient accelerators have many features which require careful modeling in simulation. They accept beams over an extremely large momentum range, generally at least a factor of 2. They often use magnets whose lengths are comparable to their apertures. The beam often makes large angles with respect to the magnet axis and pole face normal. In some applications (muons in particular), the beam occupies a substantial fraction of the magnet aperture. The longitudinal dynamics in these machines often differ significantly from what one finds in more conventional machines such as synchrotrons. These characteristics require that simulation codes be careful to avoid inappropriate approximations in describing particle motion in FFAGs. One must properly treat the coordinate system geometry independently from the magnetic fields. One cannot blindly assume that phase space variables are small. One must take magnet end fields properly into account. Finally, one must carefully consider what it means to have a ''matched'' distribution that is injected into these machines.

  13. Quantum control in spintronics

    E-Print Network [OSTI]

    Ardavan, A

    2011-01-01

    Superposition and entanglement are uniquely quantum phenomena. Superposition incorporates a phase which contains information surpassing any classical mixture. Entanglement offers correlations between measurements in quantum systems that are stronger than any which would be possible classically. These give quantum computing its spectacular potential, but the implications extend far beyond quantum information processing. Early applications may be found in entanglement enhanced sensing and metrology. Quantum spins in condensed matter offer promising candidates for investigating and exploiting superposition and entanglement, and enormous progress is being made in quantum control of such systems. In GaAs, individual electron spins can be manipulated and measured, and singlet-triplet states can be controlled in double-dot structures. In silicon, individual electron spins can be detected by ionisation of phosphorous donors, and information can be transferred from electron spins to nuclear spins to provide long memor...

  14. Photoneutron reactions in astrophysics

    SciTech Connect (OSTI)

    Varlamov, V. V., E-mail: Varlamov@depni.sinp.msu.ru; Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.; Stopani, K. A. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

    2014-12-15

    Among key problems in nuclear astrophysics, that of obtaining deeper insight into the mechanism of synthesis of chemical elements is of paramount importance. The majority of heavy elements existing in nature are produced in stars via radiative neutron capture in so-called s- and r processes, which are, respectively, slow and fast, in relation to competing ?{sup ?}-decay processes. At the same time, we know 35 neutron-deficient so-called bypassed p-nuclei that lie between {sup 74}Se and {sup 196}Hg and which cannot originate from the aforementioned s- and r-processes. Their production is possible in (?, n), (?, p), or (?, ?) photonuclear reactions. In view of this, data on photoneutron reactions play an important role in predicting and describing processes leading to the production of p-nuclei. Interest in determining cross sections for photoneutron reactions in the threshold energy region, which is of particular importance for astrophysics, has grown substantially in recent years. The use of modern sources of quasimonoenergetic photons obtained in processes of inverse Compton laser-radiation scattering on relativistic electronsmakes it possible to reveal rather interesting special features of respective cross sections, manifestations of pygmy E1 and M1 resonances, or the production of nuclei in isomeric states, on one hand, and to revisit the problem of systematic discrepancies between data on reaction cross sections from experiments of different types, on the other hand. Data obtained on the basis of our new experimental-theoretical approach to evaluating cross sections for partial photoneutron reactions are invoked in considering these problems.

  15. Mobility in Wireless Sensor Networks

    E-Print Network [OSTI]

    Mehta, Ankur Mukesh

    2012-01-01

    rate communication in an empirical WSN installation . Motecommunication for mobile MANET- WSN scenarios”. In: IEEEof Nodes in Mobile WSN”. In: IEEE Inter- national Conference

  16. Spintronics in antiferromagnets

    SciTech Connect (OSTI)

    Soh, Yeong-Ah; Kummamuru, Ravi K.

    2012-05-10

    Magnetic domains and the walls between are the subject of great interest because of the role they play in determining the electrical properties of ferromagnetic materials and as a means of manipulating electron spin in spintronic devices. However, much less attention has been paid to these effects in antiferromagnets, primarily because there is less awareness of their existence in antiferromagnets, and in addition they are hard to probe since they exhibit no net magnetic moment. In this paper, we discuss the electrical properties of chromium, which is the only elemental antiferromagnet and how they depend on the subtle arrangement of the antiferromagnetically ordered spins. X-ray measurement of the modulation wavevector Q of the incommensurate antiferromagnetic spin-density wave shows thermal hysteresis, with the corresponding wavelength being larger during cooling than during warming. The thermal hysteresis in the Q vector is accompanied with a thermal hysteresis in both the longitudinal and Hall resistivity. During cooling, we measure a larger longitudinal and Hall resistivity compared with when warming, which indicates that a larger wavelength at a given temperature corresponds to a smaller carrier density or equivalently a larger antiferromagnetic ordering parameter compared to a smaller wavelength. This shows that the arrangement of the antiferromagnetic spins directly influences the transport properties. In thin films, the sign of the thermal hysteresis for Q is the same as in thick films, but a distinct aspect is that Q is quantized.

  17. Parity Violation in Astrophysics

    E-Print Network [OSTI]

    C. J. Horowitz

    2004-10-17

    Core collapse supernovae are gigantic explosions of massive stars that radiate 99% of their energy in neutrinos. This provides a unique opportunity for large scale parity or charge conjugation violation. Parity violation in a strong magnetic field could lead to an asymmetry in the neutrino radiation and recoil of the newly formed neutron star. Charge conjugation violation in the neutrino-nucleon interaction reduces the ratio of neutrons to protons in the neutrino driven wind above the neutron star. This is a problem for r-process nucleosynthesis in this wind. On earth, parity violation is an excellent probe of neutrons because the weak charge of a neutron is much larger than that of a proton. The Parity Radius Experiment (PREX) at Jefferson Laboratory aims to precisely measure the neutron radius of $^{208}$Pb with parity violating elastic electron scattering. This has many implications for astrophysics, including the structure of neutron stars, and for atomic parity nonconservation experiments.}

  18. Superfluids in Curved Spacetime

    E-Print Network [OSTI]

    Villegas, Kristian Hauser A

    2015-01-01

    Superfluids under an intense gravitational field are typically found in neutron star and quark star cores. Most treatments of these superfluids, however, are done in a flat spacetime background. In this paper, the effect of spacetime curvature on superfluidity is investigated. An effective four-fermion interaction is derived by integrating out the mediating scalar field. The fermions interacting via the mediating gauge vector bosons is also discussed. Two possible cases are considered in the mean-field treatment: antifermion-fermion and fermion-fermion pairings. An effective action, quadratic in fermion field, and a self-consistent equation are derived for both cases. The effective Euclidean action and the matrix elements of the heat kernel operator, which are very useful in curved-spacetime QFT calculations, are derived for the fermion-fermion pairing. Finally, explicit numerical calculation of the gravitational correction to the pairing order parameter is performed for the scalar superfluid case. It is foun...

  19. Livestock Auctions in Texas. 

    E-Print Network [OSTI]

    McKenzie, Travis M. (Travis McDonald); Brotherton, Charles B. (Charles Benjamin); McNeely, John G.

    1951-01-01

    . . . . . . . . . . . . . . . . . . . . . . . . 29 1 I Sheep Sales by Weight and by the Head . . . . . . . . . . . . . . . . . . . . . . . . . 33 1 Hog Sales by Weight and by the Mead . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Horse Sales by Weight and by the Head... in the number of livestock auctions and in the numbers of cattle, sheep and hogs mar- keted by this method. A few Texas auctions were established before 1930, but the greatest growth has occurred during the past 15 years. con an( in 1 at , Several...

  20. Vegetable Gardening in Containers. 

    E-Print Network [OSTI]

    Cotner, Sam

    1981-01-01

    for a productive mini-garden. Prob lems with soil -borne diseases, nematodes or poor soil condi tions can be easily overcome by switching to a container garden. ? Extension horticu ltur ist, The Texas A&M University System. 3 Crop Selection.... Variety selection is of extreme importance. Most varieties that will do well when planted in a yard garden will also do well in containers. Some varieties of selected vegetables which are ideally suited for these mini gardens are indicated in Table...

  1. Embodiment in social psychology

    E-Print Network [OSTI]

    Meier, Brian P.; Schnall, Simone; Schwarz, Norbert; Bargh, John A.

    2012-01-01

    Embodiment in Social Psychology Brian P. Meier,a Simone Schnall,b Norbert Schwarz,c John A. Barghd aDepartment of Psychology, Gettysburg College bDepartment of Social and Developmental Psychology, University of Cambridge cDepartment of Psychology, University... of Michigan dDepartment of Psychology, Yale University Received 24 January 2011; received in revised form 20 January 2012; accepted 19 May 2012 Abstract Psychologists are increasingly interested in embodiment based on the assumption that thoughts, feelings...

  2. Microcracking in fibrous composites 

    E-Print Network [OSTI]

    Conrad, Nicholas

    1973-01-01

    Composites. (August 1973) Nicholas Conrad, B. S. , Texas A&M University Directed by: Dr. R. A, Schapery Microcracking is investigated as an important cause of nonlinear viscoelastic behavior in fibrous composites. Mechanical properties tests... are conducted on a unidirectional graphite fiber-reinforced epoxy in order to determine some aspects of nonlinear behavior, and the results of microcracking. The nature. of the microstructure of composites and the microcracking that occurs in composites...

  3. Time in quantum mechanics 

    E-Print Network [OSTI]

    Chapin, Kimberly R.

    1997-01-01

    TIME IN QUANTUM MECHANICS A Thesis by KIMBERLY R. CHAPIN Submitted to Texas A8M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Marian O. Scully (Chair... of Committee) Edward S. Fry (Member) aan Laane (Member) Thomas W. Adair, III (Head of Department) August 1997 Major Subject: Physics TIME IN QIJANTUM MECHANICS A Thesis by KIMBERLY R. CHAPIN Submitted to the Oflice of Graduate Studies of Texas A...

  4. Phototransduction in Drosophila

    E-Print Network [OSTI]

    Hardie, Roger C.; Juusola, Mikko

    2015-01-29

    alternative candidate. Indeed, evidence for an excitatory role for DAG has come from mutants of rdgA¸ encoding DAG kinase (DGK), which controls DAG levels by phosphorylating it to phosphatidic acid (PA, Figure 2B). In rdgA mutants TRP and TRPL channels... , in an energy efficient manner [54]. Conclusions Ultracompartmentalization inherent in the microvillar design, combined with Ca2+-dependent feedback, can account for many aspects of the performance of fly photoreceptors. Nevertheless, the final “messenger...

  5. Citizen science in archaeology

    E-Print Network [OSTI]

    Smith, ML

    2014-01-01

    Ge- ographic Information (VGI) in Theory and Practice,Geographic Information (VGI) encompasses both field data andlarge data sets generated by VGI also cap- ture the variable

  6. Definability in Physics

    E-Print Network [OSTI]

    David J. BenDaniel

    2008-06-11

    This paper has been withdrawn because the content has been substantially improved in a later paper, arXiv:0806.1165.

  7. Adventures in Infectious Diseases

    ScienceCinema (OSTI)

    Fisher-Hoch, Susan [University of Texas School of Public Health

    2014-06-25

    Dr. Susan Fisher-Hoch, Virologist and Epidemiologist, will discuss her research and travels associated with viral hemorrhagic fevers. From the Ebola outbreak in Reston, Virginia to outbreaks of Crimean Congo Hemorrhagic Fever in South Africa, Senegal, and Saudi Arabia, Dr. Fisher-Hoch has studied and tracked the pathophysiology of these viral diseases. These studies have led her from the Center for Disease Control in the United States, to Lyon, France where she was instrumental in designing, constructing, and rendering operational a laboratory capable of containing some of the world's most dangerous diseases.

  8. Biomarkers in autism.

    E-Print Network [OSTI]

    Goldani, AA; Downs, SR; Widjaja, F; Lawton, B; Hendren, RL

    2014-01-01

    P, Sharp F. Mechanistic biomarkers for autism treatment. MedEtiological heterogeneity in autism spectrum disorders: more8. Won H, Mah W, Kim E. Autism spectrum disorder causes,

  9. Computer Forensics In Forensis

    E-Print Network [OSTI]

    Peisert, Sean; Bishop, Matt; Marzullo, Keith

    2008-01-01

    and response team in Kansas City). KC to join high-tech ?ghtagainst high-tech crimes: FBI to open $2 million center

  10. Essays in Resource Economics

    E-Print Network [OSTI]

    Stevens, Reid Blake

    2015-01-01

    Supply Shocks in the Crude Oil Market. ” American Economicin the Global Market for Crude Oil. ” Journal of Appliedlowering the price of crude oil. The second chapter examines

  11. Ergonomics in the Biosciences

    E-Print Network [OSTI]

    Janowitz, Ira

    2010-01-01

    Gilson (ND) Laboratory ergonomics: Things you should know…Mason E, Dukes S (2003 ). Ergonomics and cytotechnologists:Ergonomics in the Biosciences Ira Janowitz, PT, CPE Lawrence

  12. Gravity in Gauge Mediation

    E-Print Network [OSTI]

    Zygmunt Lalak; Stefan Pokorski; Krzysztof Turzynski

    2008-08-18

    We investigate O'Raifeartaigh-type models for F-term supersymmetry breaking in gauge mediation scenarios in the presence of gravity. It is pointed out that the vacuum structure of those models is such that in metastable vacua gravity mediation contribution to scalar masses is always suppressed to the level below 1 percent, almost sufficient for avoiding FCNC problem. Close to that limit, gravitino mass can be in the range 10-100 GeV, opening several interesting possibilities for gauge mediation models, including Giudice-Masiero mechanism for mu and Bmu generation. Gravity sector can include stabilized moduli.

  13. Lighting in Commercial Buildings

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

    Motivation and Computation of Lighting Measures Floorspace by Lighting Equipment Configuration As described in Appendix A, for each building b, the CBECS data set has the total...

  14. Castor Beans in Texas. 

    E-Print Network [OSTI]

    Bringham, Raymond D.; Spears, Ben R.

    1960-01-01

    comprised most of the acreage in 1958 and 1959. It yielded more than 3,000 pounds per acre in 1958 where moisture and fertilizer were optimum; yields over 2,000 pounds per acre were common. DAWN is a late-maturing variety that pro- duces a few large... 296 is favored over Dawn in the Plainview area be- cause of its earlier maturity and less likelihood of frost damage before the seed mature. Sev- eral hundred acres of Dawn were grown in 1957 but an early frost seriously reduced yields ; only...

  15. Autobiography in Kenyan History

    E-Print Network [OSTI]

    Ochieng, William R.

    1985-01-01

    13 see Harry ThulAutobiography, Nairobi, 1970, pp.Press, 1960, p. 148. in Autobiography, Harvard see Ogingaxii and Pilling, J. , Autobiography and Imagination, London,

  16. Spin waves in the (

    SciTech Connect (OSTI)

    Lipscombe, O. J.; Chen, G. F.; Fang, Chen; Perring, T. G.; Abernathy, Douglas L; Christianson, Andrew D; Egami, Takeshi; Wang, Nanlin; Hu, Jiangping; Dai, Pengcheng

    2011-01-01

    We use neutron scattering to show that spin waves in the iron chalcogenide Fe{sub 1.05}Te display novel dispersion clearly different from both the first principles density functional calculations and recent observations in the related iron pnictide CaFe{sub 2}As{sub 2}. By fitting to a Heisenberg Hamiltonian, we find that although the nearest-neighbor exchange couplings in the two systems are quite different, their next-nearest-neighbor (NNN) couplings are similar. This suggests that superconductivity in the pnictides and chalcogenides share a common magnetic origin that is intimately associated with the NNN magnetic coupling between the irons.

  17. Astronomy in Ukraine

    E-Print Network [OSTI]

    Ya. V. Pavlenko; I. B. Vavilova; T. Kostiuk

    2005-12-16

    The current and prospective status of astronomical research in Ukraine is discussed. A brief history of astronomical research in Ukraine is presented and the system organizing scientific activity is described, including astronomy education, institutions and staff, awarding higher degrees/titles, government involvement, budgetary investments and international cooperation. Individuals contributing significantly to the field of astronomy and their accomplishments are mentioned. Major astronomical facilities, their capabilities, and their instrumentation are described. In terms of the number of institutions and personnel engaged in astronomy, and of past accomplishments, Ukraine ranks among major nations of Europe. Current difficulties associated with political, economic and technological changes are addressed and goals for future research activities presented.

  18. Essays in Energy Economics

    E-Print Network [OSTI]

    Spurlock, Cecily Anna

    2013-01-01

    is apparent in the electricity consumption behavior ofthe off-peak electricity consumption is not statisticallyI develop a model of electricity consumption utility and

  19. Visual Arts in Microfiche

    E-Print Network [OSTI]

    Levine, Stuart

    1978-01-01

    can then use it as a guide to go from place to place. Good in theory, but not in practice, for the thick plastic plaque kept catching on the guide mechanism, and within five minutes mine had become bent at the edges and thus prone to foul... the crudity of the mechanism, it would in practice be impossible not to jiggle the captions into view from time to time). But the result, for someone using this material in order to find something, is infuriating. With no central guide to tell you what each...

  20. Lighting in Commercial Buildings

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

    more comprehensive understanding of commercial lighting and the potential for lighting energy savings. Steps to build on this analysis can be taken in many directions. One...

  1. Hard physics in PHENIX

    E-Print Network [OSTI]

    D. Peressounko; for the PHENIX collaboration

    2005-12-08

    We review recent results on hard observables in p+p, d+A and A+A collisions obtained by the PHENIX experiment. Emphasis is put on those measurements that provide insight into the properties of hot QCD media expected to be created in nucleus-nucleus collisions at RHIC energies. Direct photon spectra, jet properties and heavy quarks production measured in p+p and d+Au collisions are compared to the same observables extracted in heavy ion collisions to find modifications due to the presence of hot QCD matter.

  2. Physical Vacuum in Superconductors

    E-Print Network [OSTI]

    Clovis Jacinto de Matos

    2009-08-31

    Although experiments carried out by Jain et al. showed that the Cooper pairs obey the strong equivalence principle, The measurement of the Cooper pairs inertial mass by Tate et al. revealed an anomalous excess of mass. In the present paper we interpret these experimental results in the framework of an electromagnetic model of dark energy for the superconductors' vacuum. We argue that this physical vacuum is associated with a preferred frame. Ultimately from the conservation of energy for Cooper pairs we derive a model for a variable vacuum speed of light in the superconductors physical vacuum in relation with a possible breaking of the weak equivalence principle for Cooper pairs.

  3. Barley Production in Texas. 

    E-Print Network [OSTI]

    Atkins, I. M.; Gardenhire, J. H.; Porter, K. B.

    1958-01-01

    . DEPARTMENT OF AGRICULTURE SUMMARY Barley is a relatively minor. crop in Texas, but it has a dual value to growers as a grain crop and as winter pasture for livestock. The use of barley as a winter pasture crop for livestock has expanded considerably... in recent years. The barley acreage is distributed widely over the State. The type and varieties of barley grow,n in cm area are determined by winter temperatures and uses made of the .cmp. All barley grown for grain in Texas is used for livestock fezd...

  4. Plasmons in strong superconductors

    E-Print Network [OSTI]

    Marcello Baldo; Camille Ducoin

    2011-06-07

    We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to, or smaller than the pairing gap. As a prototype of these systems we consider the proton component of neutron star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation mode. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high T$_c$ superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.

  5. Lighting in Commercial Buildings

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

    energy are presented in this section. Statistics are presented by subgroups based on building characteristics, and by subgroups based on lighting equipment. The three sets of...

  6. Innovations in Manufacturing

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

    agents such as nanocellulose. Read More ORNL Sponsors Winning Teams at FIRST Robotics Smoky Mountain Regionals Three Continuing on to World Competition in St. Louis Of the...

  7. ALS in the News

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

    techniques.) (Images by Lomvardas lab) Searching for the Solar System's Chemical Recipe Print Wednesday, 20 February 2013 00:00 The ratio of isotopes in elements like oxygen,...

  8. Confusion in Thermodynamics

    E-Print Network [OSTI]

    Jeremy Dunning-Davies; David Sands

    2011-05-17

    For a long time now, confusion has existed in the minds of many over the meaning of various concepts in thermodynamics. Recently, this point has been brought to people's attention by two articles appearing on the well-known archive (arxiv) web site. The content of these two pieces serves to illustrate many of the problems and has occasioned the construction of this answer to at least some of them. The position of the axiom proposed by Carath\\'eodory is central in this matter and here its position is clarified and secured within the framework of thermodynamics. In particular, its relation to the First Law is examined and justified.

  9. Sleep disturbances in psoriasis

    E-Print Network [OSTI]

    2013-01-01

    AB, Dann F, Menter A. Psoriasis and the metabolic syndrome.Sleep disturbances in psoriasis Brandon G Shutty 1 DO,Abstract BACKGROUND: Psoriasis negatively impacts sleep, but

  10. Noun Incorporation in Natchez

    E-Print Network [OSTI]

    Haas, Mary R.

    1982-01-01

    , as in the following use of ?uwah: (4) ?uwahle-hal?is 'to boil... (food, meat)', lit. 'to fire-set' le-hal?is 'to set... ' (-hal?is). And the noun ?ihi can also be incorporated, as in: (5) ?ihilaku·-haw?is 'to rinse the mouth' (laku·- is found only here but clearly... means 'to rinse', -haw? is, transitive aux. ) Besides ?ihi above, another body-part stem used in noun incorporation Kansas Wopking Papeps &n Linguistics. VoZ.7~1982. pp. 1-4. 2 in this language is ?i's 'hand' and it enters into several combinations: (6...

  11. In-Office Services:

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

    3,100 8 Consumer Protection Consumer protection (except for disputes over real estateconstruction matters) 6 Paid-In-Full 350 3 Small Claims Court - Advice and...

  12. Complexity in Big History

    E-Print Network [OSTI]

    Spier, Fred

    2011-01-01

    pressure resulting from nuclear fusion in its core. Anyand thus speeds up the nuclear fusion process. This releasesand thus slows down the nuclear fusion process again. This

  13. Multivariate Cumulates in R

    E-Print Network [OSTI]

    De Leeuw, Jan

    2012-01-01

    and Cumulants from Multivariate Distributions. StatisticsTaylor Expan- sion of a Multivariate Function. International79(3):278–305, 1991. MULTIVARIATE CUMULANTS IN R J. Morton

  14. Essays in Entrepreneurship

    E-Print Network [OSTI]

    Sarada

    2011-01-01

    can pay himself both a salary and shares in the firm. Eveninto a business owner’s salary income. To the extent that

  15. Synchrotrons in cyclotron territory

    SciTech Connect (OSTI)

    Clark, D.J.; Gough, R.A.

    1986-10-01

    Synchrotrons and cyclotrons have an overlap in their particle and energy ranges. In proton radiotherapy, synchrotrons are proposed at 250 MeV, an energy usually served by cyclotrons. Heavy ion therapy has been synchrotron territory, but cyclotrons may be competitive. In nuclear science, heavy ion synchrotrons can be used in the cyclotron energy range of 10-200 MeV/u. Storage rings are planned to increase the flexibility of several cyclotrons. For atomic physics research, several storage rings are under construction for the energy range of 10 MeV/u and below.

  16. Water in the West

    E-Print Network [OSTI]

    Fahlund, Andrew; Choy, Min L. Janny; Szeptycki, Leon

    2014-01-01

    connections between water and energy, advances in knowledgeimportant nexus between water and energy. The demand fortwo reports on the water and energy nexus highlighting the

  17. PROGRESS IN RESEARCH

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

    are performed event by event and are filtered through the experimental acceptance. The reaction products passing the filter are then analyzed in the same way as the experimental...

  18. Scheduling in Multiprocess Systems

    E-Print Network [OSTI]

    Dou, Ji Adam

    2011-01-01

    over heterogeneous mobile devices. In International WorkshopGartner says worldwide mobile device sales to end usersCloud computing on mobile devices using mapreduce. http://

  19. Essays in Entrepreneurship

    E-Print Network [OSTI]

    Sarada

    2011-01-01

    self-employment consumption . . . . . . . . . . . . . . . . .Table 1.8: Variance in Consumption Self Employed SE/Tenurebetween reported wage and consumption for the self-employed.

  20. Scheduling in Multiprocess Systems

    E-Print Network [OSTI]

    Dou, Ji Adam

    2011-01-01

    In RTSS, Lisbon, Portugal, [46] Facebook. Facebook. http://www.facebook.com. [47] Facebook.Facebook info.php? statistics, 2011. statistics. http://

  1. Explosive Nucleosynthesis in Hypernovae

    E-Print Network [OSTI]

    Takayoshi Nakamura; Hideyuki Umeda; Koichi Iwamoto; Ken'ichi Nomoto; Masa-aki Hashimoto; W. Raphael Hix; Friedrich-Karl Thielemann

    2001-03-25

    We examine the characteristics of nucleosynthesis in 'hypernovae', i.e., supernovae with very large explosion energies ($ \\gsim 10^{52} $ ergs). We carry out detailed nucleosynthesis calculations for these energetic explosions and compare the yields with those of ordinary core-collapse supernovae. We find that both complete and incomplete Si-burning takes place over more extended, lower density regions, so that the alpha-rich freezeout is enhanced and produces more Ti in comparison with ordinary supernova nucleosynthesis. In addition, oxygen and carbon burning takes place in more extended, lower density regions than in ordinary supernovae. Therefore, the fuel elements O, C, Al are less abundant while a larger amount of Si, S, Ar, and Ca ("Si") are synthesized by oxygen burning; this leads to larger ratios of "Si"/O in the ejecta. Enhancement of the mass ratio between complete and incomplete Si-burning regions in the ejecta may explain the abundance ratios among iron-peak elements in metal-poor stars. Also the enhanced "Si"/O ratio may explain the abundance ratios observed in star burst galaxies. We also discuss other implications of enhanced [Ti/Fe] and [Fe/O] for Galactic chemical evolution and the abundances of low mass black hole binaries.

  2. Farmland Reforestation in China

    E-Print Network [OSTI]

    Kelly, Peter Alfred

    2010-01-01

    suitability evaluation in desertification-affected northwind erosion and desertification plague much of China’swind erosion and desertification plague much of China’s

  3. Federal participation in LEED

    E-Print Network [OSTI]

    Payne, Christopher; Dyer, Beverly

    2004-01-01

    Federal Participation in LEED Christopher Payne 1 BeverlyBuilding Rating System (LEED). This paper presents a review16 federal buildings under LEED: three buildings using the

  4. Phonon dispersion in graphene

    E-Print Network [OSTI]

    L. A. Falkovsky

    2007-08-11

    Taking into account the constraints imposed by the lattice symmetry, the phonon dispersion is calculated for graphene with interactions between the first and second nearest neighbors in the framework of the Born-von Karman model. Analytical expressions are obtained for the out-of-plane (bending) modes determined only by two force constants as well as for the in-plane modes with four force constants. Values of the force constants are found in fitting to elastic constants and Raman frequencies observed in graphite.

  5. Art in Architecture

    E-Print Network [OSTI]

    Campbell, Robert; Cruikshank, Jeffrey

    1986-01-01

    Art in Architecture Robert Campbell and Jeffrey Cruikshank Iin contexts provided by architecture. More traditional worksto become part of the architecture. They maintain, instead,

  6. Citizen science in archaeology

    E-Print Network [OSTI]

    Smith, ML

    2014-01-01

    Melinda A. Zeder Smith] CITIZEN SCIENCE IN ARCHAEOLOGY 2014and Application of Citizen Science. Biological ConservationHilchey 2011 A Review of Citizen Science and Community-Based

  7. Astrophysics in 2004

    E-Print Network [OSTI]

    Trimble, V; Aschwanden, M

    2005-01-01

    et al. 2004, A&A, 412, 305 Pourbaix, D. , et al. 2004, A&A,is to be applauded. Pourbaix et al. (2004) have succeeded in

  8. Astrophysics in 2001

    E-Print Network [OSTI]

    Trimble, V; Aschwanden, MJ

    2002-01-01

    B. 2001, MNRAS, 322, 343 Pourbaix, D. 2001, A&A, 369, L22in turn was popped by Pourbaix (2001), who pointed out that

  9. Aging in American Convents

    E-Print Network [OSTI]

    Corwin, Anna I.

    2009-01-01

    Schuster. Snowdon, David 2001 Aging with Grace: What the Nunreligion, devotion, and aging. CSW JAN09 update tocAging in American Convents FIELDWORK REPORT by Anna I.

  10. ALS in the News

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

    Budget Request for DOE R&D DOE Scientists Team up to Demonstrate Scientific Potential of Big Data Infrastructure January Timeline Chronicles Lab's Science Highlights in 2014...

  11. In the News

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory ofDid you notHeat Pumps Heat Pumpsfacility doe logoIn Focus OurInIn theIn

  12. In Other News

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIn MemoriamIn OtherInIn

  13. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningIn otherInInIn

  14. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInIn otherInIn

  15. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInInIn otherIn

  16. In other news

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACT EVALUATION PLAN FOR THE SITE-218 58ImprovingIna miningInInInIn other

  17. In the News

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation CurrentHenry Bellamy,Impact AssessmentsImprovingIn Case ofIn SituIn ThetoIn the

  18. At Work in The World

    E-Print Network [OSTI]

    Blanc, Paul D. MD; Dolan, Brian PhD

    2012-01-01

    nuclear things in African places were produced and dissolved in frictions between the transnational politics

  19. New Developments in GIS in Water Resources

    E-Print Network [OSTI]

    Maidment, David

    2008-11-19

    for computer to computer interaction HIS Servers in the WATERS Network HIS Central at San Diego Supercomputer Center Web Services HIS Central National Water Metadata Catalog WaterML Get Data Get Metadata NWIS ArcGIS Excel Academic Unidata NASA Storet NCDC..., Vi Site, Sj End Date Time, t2 Begin Date Time, t1 Time Variables Count, C Vi Sj t2 t1 C CUAHSI National Water Metadata Catalog Indexes: 50 observation networks 1.75 million sites 8.38 million time series 342 million data values NWIS STORET...

  20. Future Trends in Microelectronics

    E-Print Network [OSTI]

    Luryi, Serge

    Future Trends in Microelectronics Reflections on the Road to Nanotechnology edited by Serge Luryi;Proceedings of the NATO Advanced Research Workshop on Future Trends in Microelectronics: Reflections is available from the Library of Congress ISBN 0-7923-4169-4 Published by Kluwer Academic Publishers, P.O. Box

  1. Fire in Buildings 

    E-Print Network [OSTI]

    Shorter, G.

    During the lifetime of any building in Canada it is probable that one or more "unwanted" fires will occur. "Fire Loss in Canada, 1959," the report of the Dominion Fire Commissioner, states that for the period 1950-1959 the average number of reported...

  2. Innovation in Computer Sciences

    E-Print Network [OSTI]

    Ghosh, Joydeep

    power- up Innovation in Computer Sciences Department of Computer Sciences at The University of Texas at Austin #12;#12;Computer science is the enabling science of our age. It is the engine. In the Department of Computer Sciences at The University of Texas at Austin, one of the top ten departments

  3. Genetics in the courts

    SciTech Connect (OSTI)

    Coyle, Heather; Drell, Dan

    2000-12-01

    Various: (1)TriState 2000 Genetics in the Courts (2) Growing impact of the new genetics on the courts (3)Human testing (4) Legal analysis - in re G.C. (5) Legal analysis - GM ''peanots'', and (6) Legal analysis for State vs Miller

  4. Quantum Engineering in Diamond 

    E-Print Network [OSTI]

    Chen, Jeson

    2015-08-06

    of the NV centers yield in bulk diamond, nanodiamond (ND) size reduction, photocurrent study of the defect band-trap electronic structure in diamonds, and optimization of high-speed NV qubit control. For NV centers yield optimization, both the experimental...

  5. Outrigger in Scandinavia

    E-Print Network [OSTI]

    Ronneby, 2007. Full- scale station in Poznan, 2009- 2010? SKA Square Kilometre Array. Australia or South diagnostics of space The Westerbork array of 14 dishes, each 25 m in diameter sees nearby objects emitting Physical Societey, A&M Conference, Uppsala, October 26, 2007 LOFAR Low Frequency Array (10­240 MHz). Test

  6. Outrigger in Scandinavia

    E-Print Network [OSTI]

    in Poznan, Poland, in the 2009-2011 timeframe. SKA Square Kilometre Array. Australia or South Africa, ~2020, Univerity of Halmstad, 5 Sep, 2008 Conventional radio diagnostics. Can we do better? The Westerbork array LOFAR Low Frequency Array (10­240 MHz). Test station at Exloo operational 2004, full scale deployment

  7. Outrigger in Scandinavia

    E-Print Network [OSTI]

    , Poland, in the 2009-2011 timeframe. SKA Square Kilometre Array. Australia or South Africa, ~2020. Very. Thidé et al., Phys. Rev. Lett. 99, 087701 (2007)], we show numerically that vector antenna arrays can? The Westerbork array of 14 dishes, each 25 m in diameter sees nearby objects emitting 1420.4 MHz (21 cm H

  8. Outrigger in Scandinavia

    E-Print Network [OSTI]

    , 2008. Full-scale station in Poznan, Poland, in the 2009-2011 timeframe. SKA Square Kilometre Array image of a nearby galaxy M31 (Andromeda, Local The array of fourteen 25 m dishes at Westerboork (NL the Epoch of Reionisation (EoR)? #12;Bo Thidé 10Asiago, 24October, 2008 LOFAR Low Frequency Array (10

  9. Photon Physics in ALICE

    E-Print Network [OSTI]

    D. Peressounko; Y. Kharlov; for the ALICE collaboration

    2009-09-17

    We give an overview of photon physics which will be studied by the ALICE experiment in proton-proton and heavy ion collisions at LHC. We compare properties of ALICE photon detectors and estimate their ability to measure neutral meson and direct photon spectra as well as gamma-hadron and gamma-jet correlations in pp and Pb+Pb collisions.

  10. Conference Program Extremism in

    E-Print Network [OSTI]

    Meyers, Steven D.

    Department of History, USF The phenomenal rise of the Islamic State in Iraq and Syria, also known as ISIS, has created a profound national security threat to the United States. However, ISIS is only one aspect of a much broader and important phenomenon in the Islamic world, namely extremism. The purpose

  11. Essays in Environmental Economics

    E-Print Network [OSTI]

    Brandes, Julia

    2014-08-31

    policy aimed at decreasing greenhouse gas emissions and its impact on the firm it is regulating. In order to increase the use of renewable energy for electricity generation, a majority of the states in the US have introduced Renewable Portfolio Standards...

  12. High Performance Computing in

    E-Print Network [OSTI]

    Stamatakis, Alexandros

    High Performance Computing in Bioinformatics Thomas Ludwig (t.ludwig@computer.org) Ruprecht PART I: High Performance Computing Thomas Ludwig PART II: HPC Computing in Bioinformatics Alexandros #12;© Thomas Ludwig, Alexandros Stamatakis, GCB'04 3 PART I High Performance Computing Introduction

  13. Renewable Energy in Alaska

    SciTech Connect (OSTI)

    Not Available

    2013-03-01

    This report examines the opportunities, challenges, and costs associated with renewable energy implementation in Alaska and provides strategies that position Alaska's accumulating knowledge in renewable energy development for export to the rapidly growing energy/electric markets of the developing world.

  14. LCLS Laser (in Polish)

    E-Print Network [OSTI]

    Romaniuk, R S

    2013-01-01

    The most powerful now in the world, American X-ray laser LCLS (Linac Coherent Light Source), has been working as a research and user facility since 2009. It is further developed to LCLSII machine at the Stanford National Accelerator Laboratory SLAC in Menlo Park CA. In a certain sense, LCLS is a response to the EXFEL machine and a logical extension of LCLS. All these machines are light sources of the fifth generation. EXFELis expected to open user facility in 2016, at a cost of over 1 bil Euro. LCLS II, which design started in 2010, will be operational in 2017. The lasers LCLS, LCLS II and EXFEL use SASE and SEED methods to generate light and are powered by electron liniacs, LCLS by a wrm one, and EXFEL by a cold one. The liniacs have energies approaching 20 GeV, and are around 2 - 3 km in length. EXFEL liniac uses SRF TESLA cavity technology at 1,3GHz. A prototype of EXFEL was FLASH laser. SLAC Laboratory uses effectively over 50 years experience in research, building and exploitation of linear electron acce...

  15. Polyhydroxyalkanoate synthesis in plants

    DOE Patents [OSTI]

    Srienc, Friedrich (Lake Elmo, MN); Somers, David A. (Roseville, MN); Hahn, J. J. (New Brighton, MN); Eschenlauer, Arthur C. (Circle Pines, MN)

    2000-01-01

    Novel transgenic plants and plant cells are capable of biosynthesis of polyhydroxyalkanoate (PHA). Heterologous enzymes involved in PHA biosynthesis, particularly PHA polymerase, are targeted to the peroxisome of a transgenic plant. Transgenic plant materials that biosynthesize short chain length monomer PHAs in the absence of heterologous .beta.-ketothiolase and acetoacetyl-CoA reductase are also disclosed.

  16. Theory in Biology Computational

    E-Print Network [OSTI]

    Goldbeter, Albert

    Magazine R601 Theory in Biology Computational biology: A propagating wave of interest Albert Goldbeter Systems biology, computational biology, integrative biology... many names are being used and tendency to take a global view of problems in biology. This field is not entirely novel, but what is clear

  17. Undergraduate programmes in Psychology

    E-Print Network [OSTI]

    Miall, Chris

    Undergraduate programmes in Psychology School of Psychology We are one of the UK's strongest psychology departments, combining outstanding research and teaching. Over half of our research was recently recognised as being `world leading', fifth in the UK. Professor Kim Shapiro Head of School of Psychology

  18. Concentration in Green Design

    E-Print Network [OSTI]

    Shewchuk, Jonathan

    , energy, infrastructure or transport. Participants in this specialization area work closely with the GreenConcentration in Green Design Research and Education Opportunities Carnegie Mellon University Civil and Environmental Engineering www.ce.cmu.edu M.S. Concentration Green Design - Course Only Track As an extension

  19. Year in review 2004

    SciTech Connect (OSTI)

    None, None

    2005-01-01

    The federal government must lead the way in reducing its energy consumption and related environmental impacts so that the rest of the country will follow our example. For this reason we often look to our leaders -- energy champions who are providing the innovation and dedication to overcome challenges in pursuing sound energy management.

  20. Mechanisms in Plant Development

    SciTech Connect (OSTI)

    Hake, Sarah

    2013-08-21

    This meeting has been held every other year for the past twenty-two years and is the only regularly held meeting focused specifically on plant development. Topics covered included: patterning in developing tissues; short and long distance signaling; differentiation of cell types; the role of epigenetics in development; evolution; growth.

  1. Tritium retention in TFTR

    SciTech Connect (OSTI)

    Dylla, H.F.; Wilson, K.L. (eds.)

    1988-04-01

    This report discusses the materials physics related to D-T operation in TFTR. Research activities are described pertaining to basic studies of hydrogenic retention in graphite, hydrogen recycling phenomena, first-wall and limiter conditioning, surface analysis of TFTR first-wall components, and estimates of the tritium inventory.

  2. Caching in wireless networks

    E-Print Network [OSTI]

    Niesen, Urs

    We consider the problem of delivering content cached in a wireless network of n nodes randomly located on a square of area n. In the most general form, this can be analyzed by considering the 2[superscript n] timesn-dimensional ...

  3. Learning in Parallel

    E-Print Network [OSTI]

    Vitter, Jeffrey Scott; Lin, Jyh-Han

    1992-01-01

    In this paper, we extend Valiant's sequential model of concept learning from examples [Valiant 1984] and introduce models for the e cient learning of concept classes from examples in parallel. We say that a concept class is NC-learnable if it can...

  4. Computer algebra in gravity

    E-Print Network [OSTI]

    Christian Heinicke; Friedrich W. Hehl

    2001-05-25

    We survey the application of computer algebra in the context of gravitational theories. After some general remarks, we show of how to check the second Bianchi-identity by means of the Reduce package Excalc. Subsequently we list some computer algebra systems and packages relevant to applications in gravitational physics. We conclude by presenting a couple of typical examples.

  5. Progress in colloid propulsion

    E-Print Network [OSTI]

    López Urdiales, Jóse Mariano, 1977-

    2004-01-01

    In the early decades of the Space Age, a great deal of work was put into the development of the Colloid Thruster as an electric propulsion system for spacecraft. In spite of the effort by the end of the 70s the programs ...

  6. We Dwell in POSSIBILITY

    E-Print Network [OSTI]

    Wenderholm, Elaine

    in the hands of our thou- sands of students and professors. And the promise of discovery and innovation and plans set forth at SUNY Oswego in 2013-14: We inhabited new buildings, with shimmering windows and solar panels. Students, including our first class of Possibility Scholars, spread wide their minds to grasp new

  7. Environmental gentrification in Berlin 

    E-Print Network [OSTI]

    Schroder, Nina

    In an age of rising global environmental concerns, cities have come to play a key role in managing environmental issues such as climate change and food security on more regional and local scales and thus have become the locus for sustainable...

  8. Parastillation Process in Operations 

    E-Print Network [OSTI]

    Canfield, F.; Jenkins, O.

    1986-01-01

    The Parastillation process is a new method for multi-stage, counter-current contact between vapor and liquid that results in 33% more ideal stages than distillation for a given tray spacing. Patents have been granted in the U.S.A., U.K., Europe...

  9. International Energy Policy in

    E-Print Network [OSTI]

    Delaware, University of

    of Energy Policies of the U.S., U.K., Germany, France, Japan, China and Korea November 2013 #12;Mailing IN THE AFTERMATH OF THE FUKUSHIMA NUCLEAR DISASTER: An Analysis of Energy Policies of the U.S., U.K., GermanyInternational Energy Policy in the Aftermath of the Fukushima Nuclear Disaster An Analysis

  10. Flax Production in Texas. 

    E-Print Network [OSTI]

    Atkins, I. M.; Reyes, Lucas; Merkle, Owen G.

    1960-01-01

    and Norland have been grown in somelr nl, sons. The Canadian varieties such as Royal# ma Raja are too early maturing and susceptihii to low-temperature injury for fall seeding in Ta ag The same is true of the recently distributed lea rieties Bolley...

  11. Introduction Transport in disordered graphene

    E-Print Network [OSTI]

    Fominov, Yakov

    Introduction Transport in disordered graphene Summary Ballistic transport in disordered graphene P, Gornyi, Mirlin Ballistic transport in disordered graphene #12;Introduction Transport in disordered graphene Summary Outline 1 Introduction Model Experimental motivation Transport in clean graphene 2

  12. Proteolysis in hyperthermophilic microorganisms

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ward, Donald E.; Shockley, Keith R.; Chang, Lara S.; Levy, Ryan D.; Michel, Joshua K.; Conners, Shannon B.; Kelly, Robert M.

    2002-01-01

    Proteases are found in every cell, where they recognize and break down unneeded or abnormal polypeptides or peptide-based nutrients within or outside the cell. Genome sequence data can be used to compare proteolytic enzyme inventories of different organisms as they relate to physiological needs for protein modification and hydrolysis. In this review, we exploit genome sequence data to compare hyperthermophilic microorganisms from the euryarchaeotal genusPyrococcus, the crenarchaeoteSulfolobus solfataricus, and the bacteriumThermotoga maritima. An overview of the proteases in these organisms is given based on those proteases that have been characterized and on putative proteases that have been identified from genomicmore »sequences, but have yet to be characterized. The analysis revealed both similarities and differences in the mechanisms utilized for proteolysis by each of these hyperthermophiles and indicated how these mechanisms relate to proteolysis in less thermophilic cells and organisms.« less

  13. Innovation Concepts in Healthcare

    E-Print Network [OSTI]

    CERN. Geneva

    2010-01-01

    AbstractDemographic change and advances in medical science pose increased challenges to healthcare systems globally: The economic basis is aging and thus health is becoming more and more a productivity factor. At the same time, with today’s new communication possibilities the demand and expectations of effective medical treatment have been increased. This presentation will illustrate the need for the “industrialization” of healthcare in order to achieve highest results at limited budgets. Thereby, industrialization is not meaning the medical treatment based on the assembly line approach. Rather it is to recognize the cost of medical care as an investment with respective expectations on the return of the investment. Innovations in imaging and pharmaceutical products as well as in processes - that lead to similar medical results, but with lower efforts - are keys in such scenarios.BiographyProf. Dr. Hermann Requardt, 54, is a member of the Managing Board of Siemens AG and Chief Executive Officer of the He...

  14. Time scales in LISA

    E-Print Network [OSTI]

    S. Pireaux

    2007-03-23

    The LISA mission is a space interferometer aiming at the detection of gravitational waves in the [$10^{-4}$,$10^{-1}$] Hz frequency band. In order to reach the gravitational wave detection level, a Time Delay Interferometry (TDI) method must be applied to get rid of (most of) the laser frequency noise and optical bench noise. This TDI analysis is carried out in terms of the coordinate time corresponding to the Barycentric Coordinate Reference System (BCRS), TCB, whereas the data at each of the three LISA stations is recorded in terms of each station proper time. We provide here the required proper time versus BCRS time transformation. We show that the difference in rate of station proper time versus TCB is of the order of $5 10^{-8}$. The difference between station proper times and TCB exhibits an oscillatory trend with a maximum amplitude of about $10^{-3}$ s.

  15. Irradiation Creep in Graphite

    SciTech Connect (OSTI)

    Ubic, Rick; Butt, Darryl; Windes, William

    2014-03-13

    An understanding of the underlying mechanisms of irradiation creep in graphite material is required to correctly interpret experimental data, explain micromechanical modeling results, and predict whole-core behavior. This project will focus on experimental microscopic data to demonstrate the mechanism of irradiation creep. High-resolution transmission electron microscopy should be able to image both the dislocations in graphite and the irradiation-induced interstitial clusters that pin those dislocations. The team will first prepare and characterize nanoscale samples of virgin nuclear graphite in a transmission electron microscope. Additional samples will be irradiated to varying degrees at the Advanced Test Reactor (ATR) facility and similarly characterized. Researchers will record microstructures and crystal defects and suggest a mechanism for irradiation creep based on the results. In addition, the purchase of a tensile holder for a transmission electron microscope will allow, for the first time, in situ observation of creep behavior on the microstructure and crystallographic defects.

  16. Coal in China

    SciTech Connect (OSTI)

    Minchener, A.J. [IEA Clean Coal Centre, London (United Kingdom)

    2005-07-01

    The article gives an overview of the production and use of coal in China, for power generation and in other sectors. Coal use for power generation was 850 million tonnes in 2003 and 800 million tonnes in the non-power sector. The majority of power will continue to be produced from coal, with a trend towards new larger pulverised coal fired units and introduction of circulating fluidised bed combustors. Stricter regulations are forcing introduction of improved pollution control technologies. It seems likely that China will need international finance to supplement private and state investment to carry out a programme to develop and apply clean coal technologies. The author concludes that there is evidence of a market economy being established but there is a need to resolve inconsistencies with the planned aspects of the economy and that additional policies are needed in certain sectors to achieve sustainable development. 1 ref., 2 figs., 2 tabs.

  17. Uncertainties in Gapped Graphene

    E-Print Network [OSTI]

    Eylee Jung; Kwang S. Kim; DaeKil Park

    2012-03-20

    Motivated by graphene-based quantum computer we examine the time-dependence of the position-momentum and position-velocity uncertainties in the monolayer gapped graphene. The effect of the energy gap to the uncertainties is shown to appear via the Compton-like wavelength $\\lambda_c$. The uncertainties in the graphene are mainly contributed by two phenomena, spreading and zitterbewegung. While the former determines the uncertainties in the long-range of time, the latter gives the highly oscillation to the uncertainties in the short-range of time. The uncertainties in the graphene are compared with the corresponding values for the usual free Hamiltonian $\\hat{H}_{free} = (p_1^2 + p_2^2) / 2 M$. It is shown that the uncertainties can be under control within the quantum mechanical law if one can choose the gap parameter $\\lambda_c$ freely.

  18. Conditional sterility in plants

    DOE Patents [OSTI]

    Meagher, Richard B. (Athens, GA); McKinney, Elizabeth (Athens, GA); Kim, Tehryung (Taejeon, KR)

    2010-02-23

    The present disclosure provides methods, recombinant DNA molecules, recombinant host cells containing the DNA molecules, and transgenic plant cells, plant tissue and plants which contain and express at least one antisense or interference RNA specific for a thiamine biosynthetic coding sequence or a thiamine binding protein or a thiamine-degrading protein, wherein the RNA or thiamine binding protein is expressed under the regulatory control of a transcription regulatory sequence which directs expression in male and/or female reproductive tissue. These transgenic plants are conditionally sterile; i.e., they are fertile only in the presence of exogenous thiamine. Such plants are especially appropriate for use in the seed industry or in the environment, for example, for use in revegetation of contaminated soils or phytoremediation, especially when those transgenic plants also contain and express one or more chimeric genes which confer resistance to contaminants.

  19. Failure mechanisms in MEMS.

    SciTech Connect (OSTI)

    Walraven, Jeremy Allen

    2003-07-01

    MEMS components by their very nature have different and unique failure mechanisms than their macroscopic counterparts. This paper discusses failure mechanisms observed in various MEMS components and technologies. MEMS devices fabricated using bulk and surface micromachining process technologies are emphasized. MEMS devices offer uniqueness in their application, fabrication, and functionality. Their uniqueness creates various failure mechanisms not typically found in their bulk or IC counterparts. In ICs, electrical precautions are taken to mitigate failure. In MEMS, both electrical and mechanical precautions must be enacted to reduce the risk of failure and increased reliability. Unlike ICs, many MEMS components are designed to interact with their environment, making the fabrication, testing, and packaging processes critical for the success of the device.

  20. Ferromagnetic polarons in manganites

    SciTech Connect (OSTI)

    Batista, C. D.; Eroles, J.; Avignon, M.; Alascio, B.

    2000-12-01

    Using the Lanczos method in linear chains we study the double exchange model in the low concentration limit, including an antiferromagnetic super-exchange K. In the strong-coupling limit we find that the ground state contains ferromagnetic polarons whose length is very sensitive to the value of K/t. We investigate the dispersion relation, the trapping by impurities, and the interaction between these polarons. As the overlap between polarons increases, by decreasing K/t, the effective interaction between them changes from antiferromagnetic to ferromagnetic. The scaling to the thermodynamic limit suggests an attractive interaction in the strong-coupling regime (J{sub h}>t) and no binding in the weak limit (J{sub h}{approx_equal}t).

  1. Catenaries in viscous fluid

    E-Print Network [OSTI]

    Chakrabarti, Brato

    2015-01-01

    This work explores a simple model of a slender, flexible structure in a uniform flow, providing analytical solutions for the translating, axially flowing equilibria of strings subjected to a uniform body force and drag forces linear in the velocities. The classical catenaries are extended to a five-parameter family of curves. A sixth parameter affects the tension in the curves. Generic configurations are planar, represented by a single first order equation for the tangential angle. The effects of varying parameters on representative shapes, orbits in angle-curvature space, and stress distributions are shown. As limiting cases, the solutions include configurations corresponding to "lariat chains" and the towing, reeling, and sedimentation of flexible cables in a highly viscous fluid. Regions of parameter space corresponding to infinitely long, semi-infinite, and finite length curves are delineated. Almost all curves subtend an angle less than $\\pi$ radians, but curious special cases with doubled or infinite ra...

  2. Buddhist Art in Nepal

    E-Print Network [OSTI]

    Deva, Krishna

    .tul BU!lclhist mCDU.Dwnt in Nepal. AccL .. dill!', (f, \\',·;,.W I( cd tl,~,cliU( n, Sl()(rr:bl1 i~ the self-bern or the Ainl'c11 in the fClm.era lntlls. Since (hc h\\'c DhFni Eucldhas pl<1)'cd <1. p,jm2 .• y 1 in dhyana, abhaya, randa anel bh!1Sparsa-mudras, confim1ing that these represent Dhy,"':.ni Budcl!ls. A pal;· of Lichchhvi clu,ityas from the Alko hiLi, lkachhc Tol, P,::.'.n, displaY' in the four niches Dhywl Buddhas seated re'pcctively in the varnda...

  3. Desalination shocks in microstructures

    E-Print Network [OSTI]

    Mani, Ali

    2011-01-01

    Salt transport in bulk electrolytes is limited by diffusion and convection, but in microstructures with charged surfaces (e.g. microfluidic devices, porous media, soils, or biological tissues) surface conduction and electro-osmotic flow also contribute to ionic fluxes. For small applied voltages, these effects lead to well known linear electrokinetic phenomena. In this paper, we predict some surprising nonlinear dynamics that can result from the competition between bulk and interfacial transport at higher voltages. When counter-ions are selectively removed by a membrane or electrode, a "desalination shock" can propagate through the microstructure, leaving in its wake an ultrapure solution, nearly devoid of co-ions and colloidal impurities. We elucidate the basic physics of desalination shocks and develop a mathematical theory of their existence, structure, and stability, allowing for slow variations in surface charge or channel geometry. Via asymptotic approximations and similarity solutions, we show that des...

  4. Dislocations in magnetohydrodynamic waves in a stellar atmosphere

    E-Print Network [OSTI]

    Ariste, A López; Khomenko, E

    2013-01-01

    We describe the presence of wavefront dislocations in magnetohydrodynamic waves in stratified stellar atmospheres. Scalar dislocations such as edges and vortices can appear in Alfv\\'en waves, as well as in general magneto-acoustic waves. We detect those dislocations in observations of magnetohydrodynamic waves in sunspots in the solar chromosphere. Through the measured charge of all the dislocations observed, we can give for the first time estimates of the modal contribution in the waves propagating along magnetic fields in solar sunspots.

  5. Time in Cosmology

    E-Print Network [OSTI]

    R. Brout; R. Parentani

    1999-02-05

    The notion of time in cosmology is revealed through an examination of transition matrix elements of radiative processes occurring in the cosmos. To begin with, the very concept of time is delineated in classical physics in terms of correlations between the succession of configurations which describe a process and a standard trajectory called the clock. The total is an isolated system of fixed energy. This is relevant for cosmology in that the universe is an isolated system which we take to be homogeneous and isotropic. Furthermore, in virtue of the constraint which arises from reparametrization invariance of time, it has total energy zero. Therefore the momentum of the scale factor is determined from the energy of matter. In the quantum theory this is exploited through use of the WKB approximation for the wave function of the scale factor, justified for a large universe. The formalism then gives rise to matrix elements describing matter processes. These are shown to take on the form of usual time dependent quantum amplitudes wherein the temporal dependence is given by a background which is once more fixed by the total energy of matter.

  6. Branes in Supergroups

    E-Print Network [OSTI]

    Thomas Creutzig

    2009-08-13

    In this thesis we initiate a systematic study of branes in Wess-Zumino-Novikov-Witten models with Lie supergroup target space. We start by showing that a branes' worldvolume is a twisted superconjugacy class and construct the action of the boundary WZNW model. Then we consider symplectic fermions and give a complete description of boundary states including twisted sectors. Further we show that the GL(1|1) WZNW model is equivalent to symplectic fermions plus two scalars. We then consider the GL(1|1) boundary theory. Twisted and untwisted Cardy boundary states are constructed explicitly and their amplitudes are computed. In the twisted case we find a perturbative formulation of the model. For this purpose the introduction of an additional fermionic boundary degree of freedom is necessary. We compute all bulk one-point functions, bulk-boundary two-point functions and boundary three-point functions. Logarithmic singularities appear in bulk-boundary as well as pure boundary correlation functions. Finally we turn to world-sheet and target space supersymmetric models. There is N=2 superconformal symmetry in many supercosets and also in certain supergroups. In the supergroup case we find some branes that preserve the topological A-twist and some that preserve the B-twist.

  7. Coarsening in granular systems

    E-Print Network [OSTI]

    Andrea Baldassarri; Andrea Puglisi; Alessandro Sarracino

    2015-04-28

    We review a few representative examples of granular experiments or models where phase separation, accompanied by domain coarsening, is a relevant phenomenon. We first elucidate the intrinsic non-equilibrium, or athermal, nature of granular media. Thereafter, dilute systems, the so-called "granular gases" are discussed: idealized kinetic models, such as the gas of inelastic hard spheres in the cooling regime, are the optimal playground to study the slow growth of correlated structures, e.g. shear patterns, vortices and clusters. In fluidized experiments, liquid-gas or solid-gas separations have been observed. In the case of monolayers of particles, phase coexistence and coarsening appear in several different setups, with mechanical or electrostatic energy input. Phenomenological models describe, even quantitatively, several experimental measures, both for the coarsening dynamics and for the dynamic transition between different granular phases. The origin of the underlying bistability is in general related to negative compressibility from granular hydrodynamics computations, even if the understanding of the mechanism is far from complete. A relevant problem, with important industrial applications, is related to the demixing or segregation of mixtures, for instance in rotating tumblers or on horizontally vibrated plates. Finally, the problem of compaction of highly dense granular materials, which has many important applications, is usually described in terms of coarsening dynamics: there, bubbles of mis-aligned grains evaporate, allowing the coalescence of optimally arranged islands and a progressive reduction of total occupied volume.

  8. Jamming in Hierarchical Networks

    E-Print Network [OSTI]

    Xiang Cheng; Stefan Boettcher

    2014-09-29

    We study the Biroli-Mezard model for lattice glasses on a number of hierarchical networks. These networks combine certain lattice-like features with a recursive structure that makes them suitable for exact renormalization group studies. In our numerical simulations here, we first explore their equilibrium properties with the Wang-Landau algorithm. Then, we investigate their dynamical behavior using a grand-canonical annealing algorithm. We find that the dynamics readily falls out of equilibrium and jams in many of our networks with certain constraints on the neighborhood occupation imposed by the Biroli-Mezard model, even in cases where exact results indicate that no ideal glass transition exists. But while we find that time-scales for the jams diverge, our simulations can not ascertain such a divergence for a packing fraction that would distinctly above random close packing. In cases where we allow hopping in our dynamical simulations, the jams on these networks generally disappear, in contrast to what has been found in lattices simulations previously.

  9. Transition temperature in QCD

    SciTech Connect (OSTI)

    Cheng, M.; Christ, N. H.; Mawhinney, R. D. [Physics Department, Columbia University, New York, New York 10027 (United States); Datta, S.; Jung, C.; Schmidt, C.; Umeda, T. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Heide, J. van der; Kaczmarek, O.; Laermann, E.; Miao, C. [Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany); Karsch, F. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany); Petreczky, P. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States); Petrov, K. [Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen (Denmark)

    2006-09-01

    We present a detailed calculation of the transition temperature in QCD with two light and one heavier (strange) quark mass on lattices with temporal extent N{sub {tau}}=4 and 6. Calculations with improved staggered fermions have been performed for various light to strange quark mass ratios in the range, 0.05{<=}m-circumflex{sub l}/m-circumflex{sub s}{<=}0.5, and with a strange quark mass fixed close to its physical value. From a combined extrapolation to the chiral (m-circumflex{sub l}{yields}0) and continuum (aT{identical_to}1/N{sub {tau}}{yields}0) limits we find for the transition temperature at the physical point T{sub c}r{sub 0}=0.457(7) where the scale is set by the Sommer-scale parameter r{sub 0} defined as the distance in the static quark potential at which the slope takes on the value (dV{sub qq}(r)/dr){sub r=r{sub 0}}=1.65/r{sub 0}{sup 2}. Using the currently best known value for r{sub 0} this translates to a transition temperature T{sub c}=192(7)(4) MeV. The transition temperature in the chiral limit is about 3% smaller. We discuss current ambiguities in the determination of T{sub c} in physical units and also comment on the universal scaling behavior of thermodynamic quantities in the chiral limit.

  10. Earthquake triggering discussed in three Frontiers in Science...

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

    Frontiers in Science lectures Earthquake triggering discussed in three Frontiers in Science lectures Earthquakes and their possible causes is the topic of the next series of...

  11. Delay in diagnosis of tuberculosis in Rawalpindi, Pakistan

    E-Print Network [OSTI]

    2011-01-01

    tuberculosis patients in Pakistan. J Pak Med Assoc 2008, 58(of tuberculosis in Rawalpindi, Pakistan. BMC Research Notestuberculosis in Rawalpindi, Pakistan Muhammad AN Saqib 1 ,

  12. "Dying in Full Detail": Mortality and Duration in Digital Documentary

    E-Print Network [OSTI]

    Malkowski, Jennifer Catherine

    2011-01-01

    historicizes death in documentary film and photography fromin either fiction or documentary film: the deathbed. DouglasMourning in Contemporary Documentary Film and Video,” in The

  13. Social learning in labor markets and in real estate brokerage

    E-Print Network [OSTI]

    Gathright, Graton Marshal Randal

    2010-01-01

    3 Reputation Transmission in Real Estate Brokerage Networksin Labor Markets and in Real Estate Brokerage A dissertationValue of Information in Real Estate Transactions,” Working

  14. Deformation mechanisms in a ferritic superalloy revealed by in...

    Office of Scientific and Technical Information (OSTI)

    Deformation mechanisms in a ferritic superalloy revealed by in situ neutron diffraction studies at elevated temperatures Citation Details In-Document Search Title: Deformation...

  15. Polymers in a vacuum

    E-Print Network [OSTI]

    J. M. Deutsch

    2007-06-13

    In a variety of situations, isolated polymer molecules are found in a vacuum and here we examine their properties. Angular momentum conservation is shown to significantly alter the average size of a chain and its conservation is only broken slowly by thermal radiation. The time autocorrelation for monomer position oscillates with a characteristic time proportional to chain length. The oscillations and damping are analyzed in detail. Short range repulsive interactions suppress oscillations and speed up relaxation but stretched chains still show damped oscillatory time correlations.

  16. Electromagnetic Probes in PHENIX

    E-Print Network [OSTI]

    Gabor David

    2006-09-21

    Electromagnetic probes are arguably the most universal tools to study the different physics processes in high energy hadron and heavy ion collisions. In this paper we summarize recent measurements of real and virtual direct photons at central rapidity by the PHENIX experiment at RHIC in p+p, d+Au and Au+Au collisions. We also discuss the impact of the results and the constraints they put on theoretical models. At the end we report on the immediate as well as on the mid-term future of photon measurements at RHIC.

  17. Water in Asbestos

    E-Print Network [OSTI]

    Fomin, Yu D; Tsiok, E N

    2015-01-01

    We present the molecular simulation study of the behavior of water and sodium chloride solution confined in lizardite asbestos nanotube which is a typical example of hydrophilic confinement. The local structure, orientational and dynamic properties are studied. It is shown that the diffusion coefficient drops about two orders of magnitude comparing to the bulk case, and water in lizardite asbestos tubes experiences vitrification rather then crystallization upon cooling in accordance with the results for some other hydrophilic confinements. The behavior of sodium chloride solutions also considered and the formation of double layer is observed. It is shower that both sodium and chlorine have larger diffusion coefficients then water.

  18. Avalanches in wood compression

    E-Print Network [OSTI]

    Tero Mäkinen; Amandine Miksic; Markus Ovaska; Mikko J. Alava

    2015-06-15

    Wood is a multi-scale material exhibiting a complex viscoplastic response. We study avalanches in small wood samples in compression. "Woodquakes" measured by acoustic emission are surprisingly similar to earthquakes and crackling noise in rocks and laboratory tests on brittle materials. Both the distributions of event energies and of waiting (silent) times follow power-laws. The stress- strain response exhibits clear signatures of localization of deformation to "weak spots" or softwood layers, as identified using Digital Image Correlation. Even though material structure-dependent localization takes place, the avalanche behavior remains scale-free.

  19. BSSN in Spherical Symmetry

    E-Print Network [OSTI]

    David Brown

    2008-08-19

    The BSSN (Baumgarte-Shapiro-Shibata-Nakamura) formulation of the Einstein evolution equations is written in spherical symmetry. These equations can be used to address a number of technical and conceptual issues in numerical relativity in the context of a single Schwarzschild black hole. One of the benefits of spherical symmetry is that the numerical grid points can be tracked on a Kruskal--Szekeres diagram. Boundary conditions suitable for puncture evolution of a Schwarzschild black hole are presented. Several results are shown for puncture evolution using a fourth--order finite difference implementation of the equations.

  20. Superradiance Transition in Graphene

    E-Print Network [OSTI]

    Alexander I. Nesterov; Fermín Aceves de la Cruz; Valeriy A. Luchnikov; Gennady P. Berman

    2015-06-12

    We study theoretically and numerically the conditions required for the appearance of a superradiance transition in graphene. The electron properties of graphene are described in the single $p_z$-orbital tight-binding approximation, in which the model is reduced to the effective two-level pseudo-spin $1/2$ system. For each level we introduce the electron transfer rate of escape into a continuum. We demonstrate that, under some conditions, the superradiance experiences the maximal quantum coherent escape to the continuum.