J/ApJ/681/1524ivo://CDS.VizieR/J/ApJ/681/1524doi:10.26093/cds/vizier.16811524CDSLai D.K.Bolte M.Johnson J.A.Lucatello S.Heger A.Woosley S.E.2017-11-06T12:23:22Z2010-11-30T12:38:47ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frline-intensitiesmetallicityeffective-temperaturechemically-peculiar-starsWe present the results of an abundance analysis for a sample of stars with -4<[Fe/H]<-2. The data were obtained with the HIRES spectrograph at Keck Observatory. The set includes 28 stars, with effective temperature ranging from 4800 to 6600K. For 13 stars with [Fe/H]<-2.6, including nine with [Fe/H]<-3.0 and one with [Fe/H]=-4.0, these are the first reported detailed abundances. For the most metal-poor star in our sample, CS 30336-049, we measure an abundance pattern that is very similar to stars in the range [Fe/H]~-3.5, including a normal C+N, abundance. We also find that it has very low but measurable Sr and Ba, indicating some neutron-capture activity even at this low of a metallicity. We explore this issue further by examining other very neutron capture-deficient stars and find that, at the lowest levels, [Ba/Sr] exhibits the ratio of the main r-process. We also report on a new r-process-enhanced star, CS 31078-018. This star has [Fe/H]=-2.85, [Eu/Fe]=1.23, and [Ba/Eu]=-0.51. CS 31078-018 exhibits an "actinide boost," i.e., much higher [Th/Eu] than expected and at a similar level to CS 31082-001. Our spectra allow us to further constrain the abundance scatter at low metallicities, which we then use to fit to the zero-metallicity Type II supernova yields of Heger & Woosley (2008arXiv0803.3161H). We find that supernovae with progenitor masses between 10 and 20M_{sun}_ provide the best matches to our abundances.2008ApJ...681.1524Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/681/1524CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/211 : Keck/HIRES Sky Line Atlas (Osterbrock+ 1997)J/A+A/305/245 : Fe I in metal-poor stars (Magain+, 1996)J/A+A/356/238 : Atmospheric parameters in metal-poor stars. III. (Carretta+,J/A+A/404/187 : Equivalent widths for metal-poor stars (Gratton+, 2003)J/AJ/128/2402 : Extremely metal-poor star candidates abundances (Lai+, 2004)J/A+A/422/527 : Metal-poor star uvby-beta photometry. X. (Schuster+, 2004)J/A+A/440/321 : Chemical abundances in 43 metal-poor stars (Jonsell+, 2005)J/A+A/522/A26 : Fe Abundances in metal-poor stars (Sbordone+ 2010)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/681/1524https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/681/1524http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/681/1524https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/681/1524https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/681/1524http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/681/1524GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/681/1524/table5 (Stellar parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/681/1524/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/681/1524/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/681/1524/table5?GETtext/xml+votable180.050000true75.31925814.11028360.0055555555555555566/51 5406 6159 8244 8766 8864 10149 10173 10430 11543 17357 18683 19017 19566 19602 23011 28540 28594 30891 30963 31377 31595 32468 36837 48286 48526 48625 48734https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/681/1524?format=asciiOpticaldefaultJ/ApJ/681/1524/table5Stellar parametersNNumber of FeI lines used for all linesmeta.numberintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar identificationmeta.id;meta.maincharprimary[Fe/H]Metallicitylog(Sun)phys.abund.ZfloatTeffEffective temperature (1)Kphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloatvtMicroturbulence velocitykm/sphys.veloc.microTurbfloatChiSlope of the trend for all lines (2)log(eV)stat.fit.paramfloatrCorresponding correlation coefficient for all linesstat.correlationfloatChi02Slope of the trend for {chi}>0.2eVlog(eV)stat.fit.paramfloatr02Corresponding correlation coefficient for {chi}>0.2eVstat.correlationfloatN02Number of FeI lines used for {chi}>0.2eVmeta.numberintChi12Slope of the trend for {chi}>1.2eVlog(eV)stat.fit.paramfloatr12Corresponding correlation coefficient for {chi}>1.2eVstat.correlationfloatN12Number of FeI lines used for {chi}>1.2eVmeta.numberintSimbadNameSimbad column added by the CDSmeta.idchar_RAPositions from Simbad (right ascension part)degpos.eq.ra;meta.main_DEPositions from Simbad (declination part)degpos.eq.dec;meta.mainJ/ApJ/681/1524/widthEquivalent widths and atomic parameters for the 28 stars (tables 2, 3 and 4 of the paper)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar designationmeta.id;meta.maincharWaveWavelength in Angstroms0.1nmem.wlfloatf_Wave[*] Flag on Wave (1)meta.codecharElementElement identificationmeta.id;phys.atmol.elementfloatlog(gf)Log of the oscillator strengthphys.atmol.oscStrengthfloatExPotExcitation potentialeVphys.atmol.excitationfloatEW? Equivalent width (m{AA})1e-13mspect.line.eqWidthfloatnullable