J/A+A/704/A44ivo://CDS.VizieR/J/A+A/704/A44CDSMontelius M.Starkenburg E.Woudenberg H.Angrilli Muglia A.,Ardern-Arentsen A.Viswanathan A.Bystrom A.Helmi A.Martin N.,Matsuno T.Navarrete C.Navarro J.2026-03-02T06:25:50Z2025-12-02T08:04:38ZCDS support team

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

cds-question@unistra.frmilky-way-galaxymagellanic-cloudsinfrared-astronomyspectroscopychemically-peculiar-starsThe most metal-poor stars in our Galaxy contain important clues of its earliest history, particularly those occupying the inner regions of the Galaxy. In the search for such metal-poor stars, large spectroscopic surveys are an invaluable tool. However, the spectra of metal-poor stars can be difficult to analyse because of the relative lack of available lines, which can also lead to misclassification. We aim to identify the stars observed by the APOGEE survey that are below the metallicity limit of APOGEE's analysis. For the highest confidence candidates, we will classify the orbital properties of the stars to investigate whether their orbital distribution matches what we would expect for stars that are this metal-poor, and to select especially interesting targets for spectroscopic follow-up purposes. We examine the properties derived by APOGEE for metal-poor stars from the literature to find signatures of stars with a metallicity below the range of the grid used for spectral analysis. Once identified within APOGEE, we compute the orbits of our metal-poor candidates using AGAMA. The calibrated APOGEE stellar parameters provide a clear signature of the most metal-poor stars in the survey, indicated by null values for their metallicities while having effective temperatures and surface gravities determined by the pipeline. From comparison with the literature, we find that, within a temperature range of 3700 - 6700 K and above a threshold of SNR>30, the vast majority of APOGEE stars without calibrated metallicities are very metal-poor. Additional cleaning by visual inspection of the spectra improves the purity of the sample further. The radial velocities provided by APOGEE, Gaia DR3 positions and astrometry along with spectrophotometric distances derived in this work, allow for the computation of their orbits. In this work, we carefully select 289 very metal-poor red giant stars (likely below [Fe/H]=-2.5) from the APOGEE results. Our sample contains 16 very metal-poor member candidates of the Magellanic Clouds as well as 14 very metal-poor stars with orbits confined to the inner Galaxy, and 13 inner Galaxy halo interlopers. These samples significantly add to the very metal-poor stars known in these regions and allow for a more detailed picture of early chemical evolution across different environments.2025A&A...704A..44Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/704/A44CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/704/A44https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/704/A44http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/704/A44https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/704/A44https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/704/A44http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/704/A44GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/704/A44/tablec1 (Observational data for Magellanic Cloud stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/704/A44/tablec1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/704/A44/tablec1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/704/A44/tablec1?GETtext/xml+votable180.050000true96.5806-70.18630.005555555555555556Cone search capability for table J/A+A/704/A44/tabled1 (Observational data for Inner stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/704/A44/tabled1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/704/A44/tabled1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/704/A44/tabled1?GETtext/xml+votable180.050000true271.0679-9.10610.005555555555555556Cone search capability for table J/A+A/704/A44/tabled2 (Observational data for Outer stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/704/A44/tabled2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/704/A44/tabled2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/704/A44/tabled2?GETtext/xml+votable180.050000true245.8491-25.76180.0055555555555555566/25939 28728 28757 28859 29184 29186 29194-29195 29199 29217 29219 29547 30772 30777 31447 32889 32945 32957 33000 33048 33280 33309 33311 33421 33813-33814 37385 37505 37528 37551 42336 42837 42977 44311 44959 47034 47970 48028 48213https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/704/A44?format=asciiInfrareddefaultJ/A+A/704/A44/tablec1Observational data for Magellanic Cloud starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia DR3 source_idmeta.id;meta.mainRAJ2000Gaia DR3 right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Gaia DR3 declination (J2000)degpos.eq.dec;meta.mainFieldAPOGEE fieldmeta.id;obs.fieldcharpmRAProper motion in RAmas/yrpos.pm;pos.eq.rafloate_pmRAError on pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in DEmas/yrpos.pm;pos.eq.decfloate_pmDEError on pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatDistDistance from this workkpcpos.distancefloate_DistError on distancekpcstat.errorfloatTeffAPOGEE effective temperatureKphys.temperature.effectivefloate_TeffAPOGEE error on TefFKstat.error;phys.temperature.effectivefloatloggAPOGEE log of surface gravitylog(cm.s**-2)phys.gravityfloate_loggAPOGEE error on logglog(cm.s**-2)stat.errorfloatLit[o] Flag for stars with literature metallicitymeta.codecharJ/A+A/704/A44/tabled1Observational data for Inner starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCodeDesignation in papermeta.idcharGaiaDR3Gaia DR3 source_idmeta.id;meta.mainRAJ2000Gaia DR3 right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Gaia DR3 declination (J2000)degpos.eq.dec;meta.mainDistDistance from this workkpcpos.distancefloate_DistError on distancekpcstat.errorfloatTeffAPOGEE effective temperatureKphys.temperature.effectivefloate_TeffAPOGEE error on TeffKstat.error;phys.temperature.effectivefloatloggAPOGEE log of surface gravitylog(cm.s**-2)phys.gravityfloate_loggAPOGEE error on logglog(cm.s**-2)stat.errorfloatRGCGalactocentric radiuskpcpos.distance;pos.galactocentricfloatmedapoMedian apocentre distancekpcpos.distancefloatzmaxMaximum distance in zkpcpos.cartesian.z;pos.galacticfloatEOrbital Energykpc.km.s**-2src.orbitaldoublemedLzMedian z component of angular momentumkpc.km/spos.cartesian.z;stat.medianfloatLit[*p] Flag for stars with literature metallicity (1)meta.codecharJ/A+A/704/A44/tabled2Observational data for Outer starsmedLzMedian z component of angular momentumkpc.km/spos.cartesian.z;stat.medianfloatLit[*p] Flag for stars with literature metallicity (1)meta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCodeDesignation in papermeta.idcharGaiaDR3Gaia DR3 source_idmeta.id;meta.mainRAJ2000Gaia DR3 right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Gaia DR3 declination (J2000)degpos.eq.dec;meta.mainDistDistance from this workkpcpos.distancefloate_DistError on distancekpcstat.errorfloatTeffAPOGEE effective temperatureKphys.temperature.effectivefloate_TeffAPOGEE error on TeffKstat.error;phys.temperature.effectivefloatloggAPOGEE log of surface gravitylog(cm.s**-2)phys.gravityfloate_loggAPOGEE error on logglog(cm.s**-2)stat.errorfloatRGCGalactocentric radiuskpcpos.distance;pos.galactocentricfloatmedapoMedian apocentre distancekpcpos.distancefloatzmaxMaximum distance in zkpcpos.cartesian.z;pos.galacticfloatEOrbital Energykpc.km.s**-2src.orbitaldouble