J/ApJ/708/560ivo://CDS.VizieR/J/ApJ/708/560doi:10.26093/cds/vizier.17080560CDSFrebel A.Simon J.D.Geha M.Willman B.2017-06-21T08:22:33Z2012-03-01T09:20:44ZCDS support team

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

cds-question@unistra.frline-intensitieschemical-abundanceschemically-peculiar-starsspectroscopygalaxiesWe present spectra of six metal-poor stars in two of the ultra-faint dwarf galaxies orbiting the Milky Way (MW), Ursa Major II, and Coma Berenices obtained with the Keck/High Resolution Echelle Spectrometer (HIRES). These observations include the first high-resolution spectroscopic observations of extremely metal-poor ([Fe/H]<-3.0) stars not belonging to the MW halo field star population. We obtain abundance measurements and upper limits for 26 elements between carbon and europium. The entire sample of stars spans a range of -3.2<[Fe/H]<-2.3, and we confirm that each galaxy contains a large intrinsic spread of Fe abundances. A comparison with MW halo stars of similar metallicities reveals substantial agreement between the abundance patterns of the ultra-faint dwarf galaxies and the MW halo for the light, {alpha}, and iron-peak elements (C to Zn). The abundances of neutron-capture elements (Sr to Eu) in the ultra-faint dwarf galaxies are extremely low, consistent with the most metal-poor halo stars, but not with the typical halo abundance pattern at [Fe/H]>~-3.0. Not only are our results broadly consistent with a galaxy formation model that predicts that massive dwarf galaxies are the source of the metal-rich component ([Fe/H]>-2.5) of the MW halo, but they also suggest that the faintest known dwarfs may be the primary contributors to the metal-poor end of the MW halo metallicity distribution.2010ApJ...708..560Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/708/560CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/191/352 : Abundances in stars of Milky Way dwarf satellites (Kirby+,J/MNRAS/380/281 : Faint galactic satellites spectroscopic survey (Martin+,https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/708/560https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/708/560http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/708/560https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/708/560https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/708/560http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/708/560GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/708/560/stars (Photometry and other stellar parameters (table 1 and 5 of the paper))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/708/560/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/708/560/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/708/560/stars?GETtext/xml+votable180.050000true132.4727563.13942780.0055555555555555566/7416 7417 26457 281362.85864675833786e-19 3.5010283109654867e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/708/560?format=asciiOpticaldefaultJ/ApJ/708/560/starsPhotometry and other stellar parameters (table 1 and 5 of the paper)SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalDwarf galaxy name (Coma Berenices or Ursa Major II)meta.id.parentcharSDSSStar SDSS designation (JHHMMSS+DDMMSS)meta.id;meta.maincharNameStar namemeta.idcharf_Name[f] Non-member star (1)meta.codecharVmag? V-band magnitude (2)magphot.mag;em.opt.Ifloatnullablermag? SDSS-DR7 r-band magnitude (2)magphot.mag;em.opt.Rfloatnullableg-r? SDSS-DR7 g-r color index (2)magphot.color;em.opt.B;em.opt.RfloatnullablerMag? Absolute r-band magnitude (2)magphys.magAbsfloatnullableTeffEffective temperature (3)Kphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H]Fe/H abundancephys.abund.FefloatVtMicroturbulent velocity {xi}km/sphys.velocfloatSloanDisplay the SDSS data for this starmeta.ref.urlcharJDJulian Date of observationdtime.epochdoubleExpExposure timehtime.duration;obs.exposurefloatS/N55000{AA} signal to noise ratio (4)stat.snrintS/N66000{AA} signal to noise ratio (4)stat.snrintS/N656500{AA} signal to noise ratio (4)stat.snrintRVHHIRES radial velocitykm/sspect.dopplerVelocfloate_RVHRVH uncertaintykm/sstat.errorfloatRVD? DEIMOS radial velocitykm/sphys.veloc;pos.heliocentricfloatnullablee_RVD? RVD uncertaintykm/sstat.errorfloatnullableCommCommentmeta.notecharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainJ/ApJ/708/560/ewEquivalent width measurements (table 4)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharIonSpecies identificationmeta.idcharlambdaWavelength in Angstroms0.1nmem.wlfloatExPot? Excitation potentialeVphys.atmol.excitationfloatnullablelog(gf)? Log of the oscillator strengthphys.atmol.oscStrengthfloatnullablel_EWLimit flag on EWmeta.code.error;spect.line.eqWidthcharEW? Equivalent width in milli-Angstroms0.1pmspect.line.eqWidthfloatnullablef_EW[s] s: indicates a spectrum synthesis measurementmeta.codecharl_log(e)Limit flag on log(e)meta.code.errorcharlog(e)? log{epsilon} abundance (H=12)phys.abundfloatnullableJ/ApJ/708/560/abundHIRES abundances of the UMa II and ComBer starsNNumber of spectra usedmeta.numberintlog(e)log{epsilon} abundance (X)phys.abundfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharIonSpecies identificationmeta.idcharl_log(e)Limit flag on logemeta.code.errorcharf_log(e)[a] distorted lines (1)meta.codecharl_[X/H]Limit flag on [X/H]meta.code.error;phys.abundchar[X/H]X/H abundancelog(Sun)phys.abundfloatl_[X/Fe]Limit flag on [X/Fe]meta.code.error;phys.abundchar[X/Fe]? X/Fe abundance (G1)log(Sun)phys.abundfloatnullableSig? Abundance uncertaintystat.errorfloatnullableJ/ApJ/708/560/table9HIRES abundances of standard star HD 122563recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharIonSpecies identificationmeta.idcharlog(e)X0? Log {epsilon} abundance (X)_0_phys.abundfloatnullablel_log(e)Limit flag on logemeta.code.errorcharlog(e)? Log {epsilon} abundance (X)phys.abundfloatnullablef_log(e)[b] neutron capture element (1)meta.codecharl_[X/H]Limit flag on [X/H]meta.code.error;phys.abundchar[X/H]? X/H abundancelog(Sun)phys.abundfloatnullablel_[X/Fe]Limit flag on [X/Fe]meta.code.error;phys.abundchar[X/Fe]? X/Fe abundance (G1)log(Sun)phys.abundfloatnullableN? Number of spectra usedmeta.numberintnullableSig? Abundance uncertaintystat.errorfloatnullableref[cd] source of the data: c=this paper, d=Aoki et al. (2007ApJ...660..747A)meta.bibchar