J/AJ/154/52ivo://CDS.VizieR/J/AJ/154/52doi:10.26093/cds/vizier.51540052CDSMatsuno T.Aoki W.Beers T.C.Lee Y.S.Honda S.2017-12-13T18:42:47Z2017-10-25T14:12:18ZCDS support team

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

cds-question@unistra.frchemically-peculiar-starschemical-abundancesline-intensitiesWe present elemental abundances for eight unevolved extremely metal-poor (EMP) stars with T_eff_>5500K, among which seven have [Fe/H]{<}-3.5. The sample is selected from the Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration (SDSS/SEGUE) and our previous high-resolution spectroscopic follow-up with the Subaru Telescope. Several methods to derive stellar parameters are compared, and no significant offset in the derived parameters is found in most cases. From an abundance analysis relative to the standard EMP star G64-12, an average Li abundance for stars with [Fe/H]<-3.5 is A(Li)=1.90, with a standard deviation of {sigma}=0.10dex. This result confirms that lower Li abundances are found at lower metallicity, as suggested by previous studies, and demonstrates that the star-to-star scatter is small. The small observed scatter could be a strong constraint on Li-depletion mechanisms proposed for explaining the low Li abundance at lower metallicity. Our analysis for other elements obtained the following results: (i) a statistically significant scatter in [X/Fe] for Na, Mg, Cr, Ti, Sr, and Ba, and an apparent bimodality in [Na/Fe] with a separation of ~0.8dex, (ii) an absence of a sharp drop in the metallicity distribution, and (iii) the existence of a CEMP-s star at [Fe/H]{simeq}-3.6 and possibly at [Fe/H]{simeq}-4.0, which may provide a constraint on the mixing efficiency of unevolved stars during their main-sequence phase.2017AJ....154...52Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/154/52CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/337 : Gaia DR1 (Gaia Collaboration, 2016)V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013)J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013)J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007)J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/154/52https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/154/52http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/154/52https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/154/52https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/154/52http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/154/52GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/154/52/table1 (Observation log for the SDSS sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/154/52/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/154/52/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/154/52/table1?GETtext/xml+votable180.050000true205.0103844-0.03854170.0055555555555555566/9072 9438 11442 17555 20171 20474 26025 27589 29777https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/154/52?format=asciidefaultJ/AJ/154/52/table6Results of the chemical abundance analysisrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameAbbreviated object identifiermeta.id;meta.maincharprimarySpeciesSpecies identifiermeta.idcharN[1/78]? Number of lines usedmeta.numberintnullablel_log(e)[<] Upper limit flag on log(e)meta.code.errorcharlog(e)[-2.07/7.34] Abundance log{epsilon}(X) (1)phys.abundfloate_log(e)[0.02/0.29]? The 1{sigma} error in log(e) (2)stat.errorfloatnullablel_[X/Fe][<] Upper limit flag on [X/Fe]meta.code.error;phys.abundchar[X/Fe][-1/6] Log abundance relative to iron (3)log(Sun)phys.abundfloate_[X/Fe][0.01/0.31]? The 1{sigma} error in [X/Fe] (2)log(Sun)stat.error;phys.abundfloatnullableJ/AJ/154/52/table1Observation log for the SDSS sampleNamemeta.idcharprimaryExpExposure timestime.duration;obs.exposurecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObjectObject name (1)meta.id;meta.maincharAbdNumber of abundances (table6)meta.numberintnullableEWNumber of measured equivalent widths (table5)meta.numberintnullableDate1Starting date of the observing runtime.startnullableDate2Second/ending date of the observing runtime.epochnullableDate3Ending date of the observing runtime.endnullableVmag? The V band magnitudemagphot.mag;em.opt.VfloatnullableS/N1? Signal-to-Noise ratio at 4877{AA}stat.snrintnullableS/N2? Signal-to-Noise ratio at 6708{AA}stat.snrintnullableRV? Radial velocity (v_r_)km/sphys.veloc;pos.heliocentricfloatnullablePapIDisplay the data from Paper I (Aoki et al. 2013,Cat. J/AJ/145/13) within 1.5''meta.ref.urlintnullableSDSSDisplay the SDSS DR9 and DR12 data within 1''meta.ref.urlcharSloanDisplay the online SDSS data for the nearest objectmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar_RAPosition from Simbad database (right ascension part)degpos.eq.ra;meta.main_DEPosition from Simbad database (declination part)degpos.eq.dec;meta.mainJ/AJ/154/52/table5Measured equivalent widthsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameAbbreviated object identifiermeta.id;meta.maincharprimarySpeciesSpecies identifiermeta.idcharlambda[4045.8/6495] Wavelength {lambda}; in {AA}0.1nmem.wldoubleEP[0/4.35] Excitation potentialeVphys.atmol.excitationfloatlog(gf)[-3.36/0.57] Log oscillator strengthphys.atmol.oscStrengthfloatEW[1/159.8] Equivalent width; in m{AA}0.1pmspect.line.eqWidthfloatRef[1/23] Reference code (1)meta.noteint