J/ApJ/855/83ivo://CDS.VizieR/J/ApJ/855/83doi:10.26093/cds/vizier.18550083CDSHansen C.J.El-Souri M.Monaco L.Villanova S.Bonifacio P.Caffau E.,Sbordone L.2019-02-25T14:18:44Z2019-02-13T07:28:07ZCDS support team

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

cds-question@unistra.frgalaxiesspectroscopychemically-peculiar-starschemical-abundancesradial-velocityvisible-astronomySagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H]>~-1) stars that suggested a top-light initial mass function (IMF). Here we present the first high-resolution, very metal-poor ([Fe/H]=-1 to -3) sample of 13 giant stars in the main body of Sgr. We derive abundances of 13 elements, namely C, Ca, Co, Fe, Sr, Ba, La, Ce, Nd, Eu, Dy, Pb, and Th, that challenge the interpretation based on previous studies. Our abundances from Sgr mimic those of the metal-poor halo, and our most metal-poor star ([Fe/H]~-3) indicates a pure r-process pollution. Abundances of Sr, Pb, and Th are presented for the first time in Sgr, allowing for age determination using nuclear cosmochronology. We calculate ages of 9+/-2.5Gyr. Most of the sample stars have been enriched by a range of asymptotic giant branch (AGB) stars with masses between 1.3 and 5M_{sun}_. SgrJ190651.47-320147.23 shows a large overabundance of Pb (2.05dex) and a peculiar abundance pattern best fit by a 3M_{sun}_ AGB star. Based on star-to-star scatter and observed abundance patterns, a mixture of low- and high-mass AGB stars and supernovae (15-25M_{sun}_) is necessary to explain these patterns. The high level (0.29+/-0.05dex) of Ca indicates that massive supernovae must have existed and polluted the early ISM of Sgr before it lost its gas. This result is in contrast with a top-light IMF with no massive stars polluting Sgr.2018ApJ...855...83Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/855/83CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/109/218 : Catalogue of globular cluster profiles (Trager+ 1995)J/AJ/120/1841 : Abundance & Kinematic of Halo & Disk Stars (Fulbright 2000)J/A+A/381/500 : Eu abundances in F and G disk stars (Koch+, 2002)J/MNRAS/340/304 : [X/Fe] of Galactic disc F and G dwarfs (Reddy+, 2003)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/AJ/127/1545 : Abundance ratios of 4 stars in Pal 12 (Cohen+, 2004)J/ApJ/617/1091 : La and Eu abundances in 85 stars (Simmerer+, 2004)J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)J/ApJ/626/446 : Effective temperature scale of FGK stars (Ramirez+, 2005)J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)J/A+A/465/815 : Abundances of Sgr dSph stars (Sbordone+, 2007)J/A+A/490/625 : Abundances of NGC 6121 red giants (Marino+, 2008)J/AJ/136/375 : Chemical composition of LMC red giants (Mucciarelli+, 2008)J/A+A/480/379 : Abundances of 59 red giants in LMC (Pompeia+, 2008)J/A+A/501/519 : Extremely metal-poor stars abundances (Bonifacio+, 2009)J/ApJS/182/51 : Transitions of rare earth elements (Lawler+, 2009)J/ApJ/695/L134 : Chemical anomalies in old LMC clusters (Mucciarelli+, 2009)J/A+A/520/A95 : Abundances of red giants in M54 & Sgr dSph (Carretta+, 2010)J/A+A/513/A62 : Sgr dSph VIMOS photom. & RVs (Giuffrida+, 2010)J/A+A/523/A17 : Individual stars in Fornax dSph center (Letarte+, 2010)J/A+A/546/A90 : NLTE analysis of Sr lines (Bergemann+, 2012)J/AJ/144/88 : Spectroscopy of 6 LMC & 3 SMC RR Lyrae (Haschke+, 2012)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJ/751/102 : Equivalent widths of 9 RGB in Carina dSph (Venn+, 2012)J/ApJ/778/149 : Abundances for 3 stars in Sgr dSph (McWilliam+, 2013)J/ApJ/787/10 : Solar s-processes with GCE model (Bisterzo+, 2014)J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014)J/AJ/148/67 : Abundances of 156 bulge red giants (Johnson+, 2014)J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)J/ApJS/214/26 : Line lists for CN isotopes transitions (Sneden+, 2014)J/ApJ/805/189 : Highly likely members of the Sgr stream (Hyde+, 2015)J/A+A/581/A70 : NLTE EWs and corrections BaII lines (Korotin+, 2015)J/ApJS/220/13 : Co I transition probabilities (Lawler+, 2015)J/ApJ/817/53 : Fe-group abundance analysis in HD84937 (Sneden+, 2016)J/A+A/605/A46 : Sgr dSph nucleus stars abundances (Mucciarelli+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/855/83https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/855/83http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/855/83https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/855/83https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/855/83http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/855/83GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/855/83/stars (Observations and stellar parameters of our Sgr (tables 1 and 2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/855/83/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/855/83/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/855/83/stars?GETtext/xml+votable180.050000true280.84614167-29.060458330.0055555555555555566/28928 48012 48033 48034 48035 48041 48042https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/855/83?format=asciiOpticaldefaultJ/ApJ/855/83/table6Line list for region around ThrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWave[4018.6/4019.4] Wavelength in Angstroms0.1nmem.wldoubleIon[23/606.1] Numeric atom/ion identifier (1)phys.atmol.ionStagedoubleExPot[0/5.4] Excitation potentialeVphys.atmol.excitationfloatlog(gf)[-9.2/-0.5] log of the oscillator strengthphys.atmol.oscStrengthfloatEdis[3.4/6.3]? Dissociation energyeVphys.energy;phys.mol.dissociationfloatnullableJ/ApJ/855/83/starsObservations and stellar parameters of our Sgr (tables 1 and 2)SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharRAJ2000[18/19] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[29/32] Degree of declination (J2000)pos.eq.dec;meta.mainExp[2410/12685] Total observing timestime.durationintSep[7.8/176.6] Distance to centre of M54 (1)arcminpos.angDistancefloatHRV[127.4/167.2] Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatTeff[4250/4975] Effective temperatureKphys.temperature.effectiveintlogg[0.03/2] Log of surface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H][-3/-1] Abundance [Fe/H]log(Sun)phys.abund.Fefloatxi[1.3/2.5] Microturbulence velocity {xi}km/sphys.veloc.microTurbfloat