J/MNRAS/546/G170ivo://CDS.VizieR/J/MNRAS/546/G170CDSLowe B.D.C.Nordlander T.Casagrande T.Da Costa G.S.Christlieb N.,Aquilina S.E.Rozanski T.Cordoni C.2026-05-04T07:43:19Z2026-02-17T11:59:47ZCDS support team

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

cds-question@unistra.frmilky-way-galaxypopulation-ii-starschemical-abundancesvisible-astronomyWe present a detailed chemical analysis study of 16 candidate metal-poor stars, previously identified with 2dF+AAOmega, using X-Shooter spectra and the Korg 1D LTE spectral synthesis code. We generally confirm the earlier metallicity estimates and reveal six EMP ([Fe/H]<-3) stars in the current sample. Two of these stars, including the most metal-poor at [Fe/H]=-3.89+/-0.07, are kinematically associated with the GSE accretion event, increasing the number of known GSE stars with [Fe/H]<-3.5 to eight. From the X-Shooter spectra we determine abundances for 16 elements, with the element-to-iron abundance ratios generally consistent with high-resolution studies of Galactic halo stars. Within the sample, we identify three peculiar stars: the first is a GSE nitrogen enhanced metal poor (NEMP; [N/Fe]=1.60+/-0.10 and [C/Fe]=0.23+/-0.08) star with unusually high Na ([Na/Fe]=2.26+/-0.07) and Li (A(Li)_3DNLTE_=1.90+/-0.08) abundances, but lacking enhancements in [Al/Fe] or [Mg/Fe]. The second is a halo r-II star significantly enhanced in Sr ([Sr/Ba]=0.39+/-0.08), suggesting mixture of r-process and s-process enrichment, uncommon for r-II stars. Whilst the third is a halo star very depleted in N ([N/Fe]<-1.13), with low C ([C/Fe]=-0.33+/-0.08) and otherwise 'normal' [X/Fe] abundances, suggesting enrichment with Type II supernova that proceeds enrichment from massive AGB stars. This study reveals the substantial degree of chemical diversity in the stellar populations which assembled the early Milky Way.2026MNRAS.546ag170Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/546/G170CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/546/G170https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/546/G170http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/546/G170https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/546/G170https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/546/G170http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/546/G170GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/546/G170/table1 (Program stars and observational parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/546/G170/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/546/G170/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/546/G170/table1?GETtext/xml+votable180.050000true13.2560174502753-71.16649691591340.0055555555555555566/29226 29319 29329 29418 30843 33319 37809 42322-42323 42328 42936 42939 42945 42947 43003 478601.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/546/G170?format=asciiOpticaldefaultJ/MNRAS/546/G170/table1Program stars and observational parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idchar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.raindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decindexedGaiaDR3Gaia DR3 source identifiermeta.id;meta.mainRAJ2016Right ascension (J2016)degpos.eq.ra;meta.mainDEJ2016Declination (J2016)degpos.eq.dec;meta.mainGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latdoubleplxParallaxmaspos.parallax.trigdoublee_plxParallax errormasstat.error;pos.parallaxdoubleGmagGaia DR3 G apparent magnitudemagphot.mag;em.optdoubleE(B-V)corrReddening correction (1)magphot.mag;arith.diffdoubleOrbitOrbit classification (1) (2)meta.codecharJ/MNRAS/546/G170/table2Observing detailsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idcharNobsNumber of exposures takenmeta.numberintExpTimeExposure lengthsphys.size;obs.exposureintsnrUVBSignal-to-noise in UVB (1)stat.snrdoublesnrVISSignal-to-noise in VIS (1)stat.snrdoubleRVavgAverage heliocentric radial velocity (2)km/sspect.dopplerVeloc;pos.heliocentric;stat.meandoublee_RVavgHeliocentric radial velocity errorkm/sstat.errordoubleJ/MNRAS/546/G170/table3Median abundance errorsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintElElement identifiermeta.id;phys.atmol.elementchare[X/Fe]Teff? Median error of [X/Fe] when perturbing Teff by +100Kstat.errordoublenullablee[X/Fe]logg? Median error of [X/Fe] when perturbing logg by +0.3dexstat.errordoublenullablee[X/Fe]vmic? Median error of [X/Fe] when perturbing vmic by +0.3km/sstat.errordoublenullableJ/MNRAS/546/G170/table4Stellar parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idcharTeffEffective temperature (1)Kphys.temperature.effectivedoublee_TeffUncertainty in teff (1)Kstat.error;phys.temperature.effectivedoubleloggSurface gravity (1)log(cm.s**-2)phys.gravitydoublee_loggUncertainty in logg (1)log(cm.s**-2)stat.errordouble[Fe/H]Metallicity [Fe/H]phys.abund.Zdoublee_[Fe/H]Uncertainty in [Fe/H]stat.error;phys.abund.FedoublevmicMicroturbulence velocity (2)km/sphys.veloc.microTurbdoublee_vmicMicroturbulence velocity errorkm/sstat.errordoubleJ/MNRAS/546/G170/table5Chemical abundancese_[X/H]? Uncertainty in [X/H] (2)stat.error;phys.abunddoublenullable[X/H]ul? Upperlimit in [X/H] (3)phys.abund.FedoublenullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idcharElElement identifiermeta.id;phys.atmol.elementcharDet[Y/N] Detection of element (1)meta.codechar[X/Fe]? Abundance [X/Fe] (2)phys.abunddoublenullablee_[X/Fe]? Uncertainty in [X/Fe] (2)stat.error;phys.abunddoublenullable[X/Fe]ul? Upperlimit in [X/Fe] (3)phys.abund.Fedoublenullable[X/H]? Abundance [X/H] (2)phys.abunddoublenullableJ/MNRAS/546/G170/table6[C/N] abundancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifier (1)meta.idcharDet[Y/N] Detection of element (2)meta.codechar[N/Fe]? [N/Fe] abundance (3)phys.abunddoublenullablee_[N/Fe]? Uncertainty in [N/Fe] (3)stat.error;phys.abunddoublenullable[N/Fe]ul? Upperlimit in [N/Fe] (4)phys.abundfloatnullable[C/N]? [C/N] abundance (3)phys.abunddoublenullablee_[C/N]? Uncertainty in [C/N] (3)stat.error;phys.abunddoublenullable[C/N]ll? Lowerlimit in [C/N] (4)phys.abunddoublenullableJ/MNRAS/546/G170/table7[alpha/Fe] abundancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idchar[Fe/H]Metallicity [Fe/H]phys.abund.Zdoublee_[Fe/H]Uncertainty in [Fe/H]stat.error;phys.abund.Fedouble[alpha/Fe]Abundance [alpha/Fe] (1)phys.abunddoublee_[alpha/Fe]Uncertainty in [Alpha/Fe]stat.error;phys.abunddoubleJ/MNRAS/546/G170/table8[Sr/Ba] and [Ba/H] abundancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idcharDet[Y/N] Detection of element (1)meta.codechar[Ba/H]? Abundance [Ba/H] (2)phys.abunddoublenullablee_[Ba/H]? Uncertainty in [Ba/H] (2)stat.error;phys.abunddoublenullable[Ba/H]ul? Upperlimit in [Ba/H] (3)phys.abunddoublenullable[Sr/Ba]? Abundance [Sr/Ba] (2)phys.abunddoublenullablee_[Sr/Ba]? Uncertainty in [Sr/Ba] (2)stat.errordoublenullable[Sr/Ba]ll? Lowerlimit in [Sr/Ba] (3)phys.abunddoublenullableJ/MNRAS/546/G170/tables1Windows used for abundance determinationrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintElElement identifiermeta.id;phys.atmol.elementcharLineRest wavelength of line (1)0.1nmem.wl;spect.linedoubleWaveminMinimum wavelength for fitting window0.1nmem.wldoubleWavemaxMaximum wavelength for fitting window0.1nmem.wldoubleJ/MNRAS/546/G170/tables2Na windows used for each starrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifier (1)meta.idcharLineRest wavelength of line (2)0.1nmem.wl;spect.linedoubleWaveminMinimum wavelength for fitting window0.1nmem.wldoubleWavemaxMaximum wavelength for fitting window0.1nmem.wlfloatJ/MNRAS/546/G170/tables3CaII NLTE corrections and continuum offsetsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idcharLineRest wavelength of line0.1nmem.wl;spect.linedoublecntmOffsetContinuum offset for synthetic spectrastat.fit.paramfloatNLTEcorrNLTE correction for CaII (1)arith.factordouble[Ca/Fe]NLTE-corrected [Ca/Fe] abundancephys.abunddoubleJ/MNRAS/546/G170/tables4Evolutionary corrections for CHrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarIdStar source identifiermeta.idchar[C/Fe]corrEvolutionary Correction (1)arith.factorfloat