J/ApJ/954/55ivo://CDS.VizieR/J/ApJ/954/55doi:10.26093/cds/vizier/ba-xt-1qCDSRoederer I.U.Pace A.B.Placco V.M.Caldwell N.Koposov S.E.Mateo M.,Olszewski E.W.Walker M.G.2026-07-02T12:00:37Z2025-12-08T09:24:50ZCDS support team

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

cds-question@unistra.frdwarf-galaxiesvisible-astronomyspectroscopychemical-abundancesline-intensitiesinterstellar-reddeningWe present the stellar parameters and chemical abundances of 30 elements for five stars located at large radii (3.5-10.7 times the half-light radius) in the Sextans dwarf spheroidal galaxy. We selected these stars using proper motions, radial velocities, and metallicities, and we confirm them as metal-poor members of Sextans with -3.34<=[Fe/H]<=-2.64 using high-resolution optical spectra collected with the Magellan Inamori Kyocera Echelle spectrograph. Four of the five stars exhibit normal abundances of C (-0.34<=[C/Fe]<=+0.36), mild enhancement of the {alpha} elements Mg, Si, Ca, and Ti ([{alpha}/Fe]=+0.12+/-0.03), and unremarkable abundances of Na, Al, K, Sc, V, Cr, Mn, Co, Ni, and Zn. We identify three chemical signatures previously unknown among stars in Sextans. One star exhibits large overabundances ([X/Fe]>+1.2) of C, N, O, Na, Mg, Si, and K, and large deficiencies of heavy elements ([Sr/Fe]=-2.37+/-0.25, [Ba/Fe]=-1.45+/-0.20, [Eu/Fe]<+0.05), establishing it as a member of the class of carbon-enhanced metal-poor stars with no enhancement of neutron-capture elements. Three stars exhibit moderate enhancements of Eu (+0.17<=[Eu/Fe]<=+0.70), and the abundance ratios among 12 neutron-capture elements are indicative of r-process nucleosynthesis. Another star is highly enhanced in Sr relative to heavier elements ([Sr/Ba]=+1.21+/-0.25). These chemical signatures can all be attributed to massive, low-metallicity stars or their end states. Our results, the first for stars at large radius in Sextans, demonstrate that these stars were formed in chemically inhomogeneous regions, such as those found in ultra- faint dwarf galaxies.2023ApJ...954...55Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/954/55CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/350 : Gaia EDR3 (Gaia Collaboration, 2020)V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/AJ/90/2221 : UMi dwarf galaxy BV photometry (Olszewski+, 1985)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/A+A/435/373 : Broadening of Fe II lines by H collisions (Barklem+, 2005)J/AJ/131/375 : Phot. and velocities of Sculptor dSph giants (Westfall+, 2006)J/ApJS/162/227 : Transition probabilities for SmII (Lawler+, 2006)J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007)J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)J/AJ/137/3100 : Radial velocities of 4 dSph galaxies (Walker+, 2009)J/ApJS/182/51 : Transition prob. of rare earth elements (Lawler+, 2009)J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009)J/A+A/503/541 : Li in late-type stars non-LTE calculations (Lind+, 2009)J/A+A/522/A26 : Fe Abundances in metal-poor stars (Sbordone+ 2010)J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)J/ApJ/724/975 : Heavy elements abund. of metal-poor stars (Roederer+, 2010)J/MNRAS/411/1013 : CaII triplet in Sextans dSph galaxy (Battaglia+, 2011)J/ApJS/194/35 : Atomic transition probabilities of Mn (Den Hartog+, 2011)J/ApJ/750/76 : r-process peaks elements in HD 160617 (Roederer+, 2012)J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)J/ApJS/211/20 : NiI transition probability measurements (Wood+, 2014)J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)J/ApJS/215/20 : Vanadium log(gf) and transition probabilities (Lawler+, 2014)J/ApJS/220/13 : Co I transition probabilities (Lawler+, 2015)J/MNRAS/460/30 : gi photometry of Sextans dSph galaxy stars (Roderick+, 2016)J/ApJS/228/10 : Transition prob. for 183 lines of Cr II (Lawler+, 2017)J/A+A/609/A53 : Tracing stars of MW dwarf galaxies: Sextans (Cicuendez+, 2018)J/ApJ/860/125 : Six warm metal-poor stars iron abundances (Roederer+, 2018)J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)J/ApJS/249/30 : R-Process Alliance: metal-poor star sp. (Holmbeck+, 2020)J/A+A/641/A127 : 13 dsph and ultra-faint galaxies analysis (Reichert+, 2020)J/A+A/642/A176 : Chemical evolution of dSph galaxy Sextans (Theler+, 2020)J/ApJ/953/31 : Abund. in warm VMP stars from Keck/HIRES sp. (Sneden+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/954/55https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/954/55http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/954/55https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/954/55https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/954/55http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/954/55GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/954/55/table1 (Star names, coordinates, photometry, and reddening)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/954/55/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/954/55/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/954/55/table1?GETtext/xml+votable180.050000true152.00641670.01891670.0055555555555555566/27205-27207 27216 27218 272261.9867573869263685e-19 4.653515163505597e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/954/55?format=asciiOpticaldefaultJ/ApJ/954/55/table1Star names, coordinates, photometry, and reddeningrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSNRSignal-to-noise ratio (1)stat.snrcharGaiaEDR3Gaia EDR3 identifiermeta.id;meta.mainSDSSSDSS DR13 name (JHHMMSS.ss+DDMMSS.s)meta.idcharOIDOther identifier (abbreviated name)meta.idcharprimaryRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainRe/Rh[3.04/10.68] Re to Rh ratio (2)phys.size.radius;arith.ratiofloatSimbadSimbad column added by the CDSmeta.ref.urlcharGmag[16.75/18.49] Gaia G-band magnitudemagphot.mag;em.optfloatgmag[17.86/18.8] SDSS g-band magnitudemagphot.mag;em.opt.BfloatBmag[18.48/19.38] B magnitude (3)magphot.mag;em.opt.BfloatVmag[17.27/18.27] V magnitude (3)magphot.mag;em.opt.VfloatE(B-V)SF[0.027/0.043] Reddening from dust maps in Schlafly & Finkbeiner (2011ApJ...737..103S)magphot.color.excessfloatl_E(B-V)NaLimit flag on E(B-V)Nameta.code.errorcharE(B-V)Na[0.01/0.07]? Reddening from the interstellar NaI D absorptionmagphot.color.excessfloatnullableE(B-V)[0.02/0.05]? Adopted reddeningmagphot.color.excessfloatnullableEWsDisplay the equivalent width measurements for this star (link to Table 4)meta.ref.urlcharSloanDisplay the online SDSS-DR18 data for the nearest objectmeta.ref.urlcharJ/ApJ/954/55/table4Line atomic data and derived abundancesEWJ1015-0238? Equivalent width in milli Angstroms for star JJ1015-02380.1pmspect.line.eqWidthfloatnullablel_logeJ1015-0238? Limit on log epsilon abundance for star JJ1015-0238meta.code.errorcharlogeJ1015-0238[-2.7/6.7]? Log epsilon abundance for star JJ1015-0238phys.abundfloatnullableNLTEcJ1015-0238? NLTE correction to log epsilon abundance for star JJ1015-0238phys.abund;arith.difffloatnullableEWJ1018-0155? Equivalent width in milli Angstroms for star J1018-01550.1pmspect.line.eqWidthfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIonSpeciesphys.atmol.ionStagecharlambda[3907/8807] Wavelength in Angstroms0.1nmem.wlfloatExPot[0/6.21] Excitation potentialeVphys.atmol.excitationfloatloggf[-10.3/0.7] Log of degeneracy times oscillator strengthphys.atmol.oscStrengthfloate_loggf[0.01/0.3] Mean error on log of degeneracy times oscillator strengthstat.error;phys.atmol.oscStrengthfloatr_loggf[1/36] Reference for log of degeneracy times oscillator strength (1)meta.ref;phys.atmol.oscStrengthintEWJ1008+0001? Equivalent width in milli Angstroms for star J1008+00010.1pmspect.line.eqWidthfloatnullablel_logeJ1008+0001? Limit on log epsilon abundance for star J1008+0001meta.code.errorcharlogeJ1008+0001[-2.5/8.1]? Log epsilon abundance for star J1008+0001phys.abundfloatnullableNLTEcJ1008+0001? NLTE correction to log epsilon abundance for star J1008+0001phys.abund;arith.difffloatnullableEWJ1010-0220? Equivalent width in milli Angstroms for star J1010-02200.1pmspect.line.eqWidthfloatnullablel_logeJ1010-0220? Limit on log epsilon abundance for star J1010-0220meta.code.errorcharlogeJ1010-0220[-2.3/6.7]? Log epsilon abundance for star J1010-0220phys.abundfloatnullableNLTEcJ1010-0220? NLTE correction to log epsilon abundance for star J1010-0220phys.abund;arith.difffloatnullablel_logeJ1018-0155? Limit on log epsilon abundance for star J1018-0155meta.code.errorcharlogeJ1018-0155[-2.01/6.8]? Log epsilon abundance for star J1018-0155phys.abundfloatnullableNLTEcJ1018-0155? NLTE correction to log epsilon abundance for star J1018-0155phys.abund;arith.difffloatnullableEWJ1018-0209? Equivalent width in milli Angstroms for star J1018-02090.1pmspect.line.eqWidthfloatnullablel_logeJ1018-0209? Limit on log epsilon abundance for star J1018-0209meta.code.errorcharlogeJ1018-0209[-2.14/6.9]? Log epsilon abundance for star J1018-0209phys.abundfloatnullableNLTEcJ1018-0209? NLTE correction to log epsilon abundance for star J1018-0209phys.abund;arith.difffloatnullable