J/AJ/144/168ivo://CDS.VizieR/J/AJ/144/168doi:10.26093/cds/vizier.51440168CDSKirby E.N.Cohen J.G.2017-12-07T07:27:24Z2014-01-16T08:39:50ZCDS support team

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

cds-question@unistra.frline-intensitieschemical-abundancesgalaxieschemically-peculiar-starsspectroscopyThe most metal-poor stars in dwarf spheroidal galaxies (dSphs) can show the nucleosynthetic patterns of one or a few supernovae (SNe). These SNe could have zero metallicity, making metal-poor dSph stars the closest surviving links to Population III stars. Metal-poor dSph stars also help to reveal the formation mechanism of the Milky Way (MW) halo. We present the detailed abundances from Keck/HIRES spectroscopy for two very metal-poor stars in two MW dSphs. One star, in the Sculptor dSph, has [FeI/H]=-2.40. The other star, in the Ursa Minor dSph, has [FeI/H]=-3.16. Both stars fall in the previously discovered low-metallicity, high-[{alpha}/Fe] plateau. Most abundance ratios of very metal-poor stars in these two dSphs are largely consistent with very metal-poor halo stars. However, the abundances of Na and some r-process elements lie at the lower end of the envelope defined by inner halo stars of similar metallicity. We propose that the metallicity dependence of SN yields is the cause. The earliest SNe in low-mass dSphs have less gas to pollute than the earliest SNe in massive halo progenitors. As a result, dSph stars at -3<[Fe/H]<-2 sample SNe with [Fe/H]{Lt}-3, whereas halo stars in the same metallicity range sample SNe with [Fe/H]~-3. Consequently, enhancements in [Na/Fe] and [r/Fe] were deferred to higher metallicity in dSphs than in the progenitors of the inner halo.2012AJ....144..168Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/144/168CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/271 : TASS Mark IV patches photometric catalog, version 2 (Droege+, 2007)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)II/237 : Stellar Photometry in Johnson's 11-color system (Ducati, 2002)III/211 : Keck/HIRES Sky Line Atlas (Osterbrock+ 1997)J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)J/ApJS/191/352 : Abundances in stars of MW dwarf satellites (Kirby+, 2010)J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010)J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009)J/ApJ/701/1053 : Abundances of 8 stars in the Draco dSph (Cohen+, 2009)J/AJ/132/137 : Abundances of extremely metal-poor carbon stars (Cohen+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/144/168https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/144/168http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/144/168https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/144/168https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/144/168http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/144/168GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/144/168/table1 (HIRES observations and data quality)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/144/168/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/144/168/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/144/168/table1?GETtext/xml+votable180.050000true15.175-33.719170.0055555555555555566/10476 11691 26457 35720https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/144/168?format=asciiOpticaldefaultJ/AJ/144/168/table1HIRES observations and data qualitySimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintf_Name[PS] P=program star, S=abundance standardmeta.codecharNameStar name (Scl=Sculptor, UMi=Ursa Minor)meta.numbercharprimaryRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainf_RAJ2000[a] Correction flag in RAm (1)meta.codecharDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainVmag[6.19/18.41]? V band magnitude (2)magphot.mag;em.opt.VfloatnullableV-I? The V-I color index (2)magphot.color;em.opt.V;em.opt.IfloatnullableV-J? The V-J color index (2)magphot.color;em.opt.V;em.IR.JfloatnullableV-K? The V-K color index (2)magphot.color;em.opt.V;em.IR.KfloatnullableDateUT date of observationtime.epoch;obsnullableN1Number of exposuresmeta.numberintT1Exposure timemintime.duration;obs.exposureintN2? 2^nd^ number of exposuresmeta.numberintnullableT2? 2^nd^ exposure timemintime.duration;obs.exposureintnullableExp? Total exposure timemintime.duration;obs.exposureintnullableSSeeingarcsecinstr.obsty.seeingfloatlam0[3185/3927] Spectral range: lower limit ({AA})0.1nminstr.bandwidthintlam1[5993/8364] Spectral range: upper limit ({AA})0.1nminstr.bandwidthintRes[29300/37300] Resolving power (3)spect.resolutionintS/N[91/566]? Signal-to-noise ratio per FWHM resolution element at 5750{AA}stat.snr;pos.angResolutionintnullableHRV[-244.48/98.87] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_HRVUncertainty in HRVkm/sstat.errorfloatEWName of the column in table2 giving the equivalent widths for this star (added at CDS)meta.ref.urlcharK10Cross-match with the catalog of medium-resolution spectroscopic abundance measurements of Kirby et al. (2010, cat. J/ApJS/191/352) within 6"meta.ref.urlintnullableJ/AJ/144/168/table2Line list with equivalent widthsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintElElement identificationmeta.id;phys.atmol.elementcharIonIonization state (I=neutral; II=ionized)phys.atmol.ionStagenullablelambda[3538.52/7797.59] Wavelength; in {AA}0.1nmem.wlfloatEPExcitation potentialeVphys.atmol.excitationfloatloggfLogarithm of oscillator strengthphys.atmol.oscStrengthfloatl_EW1Limit flag on EW1meta.code.errorcharEW1? HD 115444 equivalent width; in m{AA} (1)0.1pmspect.line.eqWidthfloatnullablee_EW1? Noise error in EW1; in m{AA} (2)0.1pmstat.errorfloatnullables_EW1? DAOSPEC error in EW1; in m{AA} (3)0.1pmstat.errorfloatnullablel_EW2Limit flag on EW2meta.code.errorcharEW2? HD 122563 equivalent width; in m{AA} (1)0.1pmspect.line.eqWidthfloatnullablee_EW2? Noise error in EW2; in m{AA} (2)0.1pmstat.errorfloatnullables_EW2? DAOSPEC error in EW2; in m{AA} (3)0.1pmstat.errorfloatnullablel_EW3Limit flag on EW3meta.code.errorcharEW3? Scl 1019417 equivalent width; in m{AA} (1)0.1pmspect.line.eqWidthfloatnullablee_EW3? Noise error in EW3; in m{AA} (2)0.1pmstat.errorfloatnullables_EW3? DAOSPEC error in EW3; in m{AA} (3)0.1pmstat.errorfloatnullablel_EW4Limit flag on EW4meta.code.errorcharEW4? UMi 20103 equivalent width; in m{AA} (1)0.1pmspect.line.eqWidthfloatnullablee_EW4? Noise error in EW4; in m{AA} (2)0.1pmstat.errorfloatnullables_EW4? DAOSPEC error in EW4; in m{AA} (3)0.1pmstat.errorfloatnullableJ/AJ/144/168/table4Abundanceseps? Abundance {epsilon} of the species (2)phys.abundfloatnullablel_[X/Fe]Limit flag on [X/Fe]meta.code.error;phys.abundchar[X/Fe]? [X/Fe] abundance relative to the solar abundance (3)log(Sun)phys.abundfloatnullablef_[X/Fe][a] [X/Fe] is relative to H ([Fe/H])meta.codechare_[X/Fe]? Uncertainty in {epsilon} due to spectral noise ({delta}_noise_{epsilon}) (4)log(Sun)stat.error;phys.abundfloatnullables_[X/Fe]? Systematic error in {epsilon} due to uncertainty in atomic parameters for each line ({delta}_sys_{epsilon}) (4)log(Sun)stat.error.sysfloatnullablel_epsLimit flag on Epsmeta.code.errorcharN? Number of linesmeta.numberintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.numbercharElElement identification (1)meta.id;phys.atmol.elementcharIonIonization state (I=neutral; II=ionized)phys.atmol.ionStagenullable