J/A+A/638/A122ivo://CDS.VizieR/J/A+A/638/A122doi:10.26093/cds/vizier.36380122CDSCaffau E.Monaco L.Bonifacio P.Sbordone L.Haywood M.Spite M.,Di Matteo P.Spite F.Mucciarelli A.Francois P.Matas Pinto A.M.2022-09-05T13:46:59Z2020-06-23T08:03:46ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyhigh-velocity-starschemical-abundancesThe search for stars born in the very early stages of the Milky Way star formation history is of paramount importance in the study of the early Universe since their chemistry carries irreplaceable information on the conditions in which early star formation and galaxy buildup took place. The search for these objects has generally taken the form of expensive surveys for faint extremely metal-poor stars, the most obvious but not the only candidates to a very early formation. Thanks to Gaia DR2 radial velocities and proper motions, we identified 72 bright cool stars displaying heliocentric transverse velocities in excess of 500km/s. These objects are most likely members of extreme outer-halo populations, either formed in the early Milky Way build-up or accreted from since-destroyed self-gravitating stellar systems. We analysed low-resolution FORS spectra of the 72 stars in the sample and derived the abundances of a few elements. Despite the large uncertainties on the radial velocity determination, we derived reliable orbital parameters for these objects. The stars analysed are mainly slightly metal poor, with a few very metal-poor stars. Their chemical composition is much more homogeneous than expected. All the stars have very eccentric halo orbits, some extending well beyond the expected dimension of the Milky Way. These stars can be the result of a disrupted small galaxy or they could have been globular cluster members. Age estimates suggest that some of them are evolved blue stragglers, now on the subgiant or asymptotic giant branches.2020A&A...638A.122Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/638/A122CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/638/A122https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/638/A122http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/638/A122https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/638/A122https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/638/A122http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/638/A122GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/638/A122/kinemats (Kinematic parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/638/A122/kinemats?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/638/A122/kinemats?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/638/A122/kinemats?GETtext/xml+votable180.050000true337.322067746971-59.63629416590710.0055555555555555566/16492 20552 24734 32892 33108 33286 33305 33380 33419 33461 33531 34233 34455 34825 34828 34868 34989 35141 35366 35407 35587 35589 36386 36868 36872 38164 38289 38382 41152 41157 41352 43133 43956-43957 45078 45215 45298 45304 45324 45409 45452 45491 45523 45532 45645 45657 45695 45785 45835 45857 45859 45867 45894 45950 45971 45988 46044 46050 46114 46121 46145 46186 46661 46669 46742 46744 47420 47456 47509 47587 48173 48263https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/638/A122?format=asciidefaultJ/A+A/638/A122/kinematsKinematic parametersStarStellar name (GHSNN)meta.id;meta.maincharSimbadNameSimbad column added by the CDSmeta.idcharnullableEnergy? Energy per mass [km/s^2^]^2^km**2.s**-4phys.massdoublenullableLz? Vertical component of the angular momentumkpc.km/sphys.angMomentumdoublenullable_RA.icrsRight ascension (ICRS) at Epoch=J2015.5 (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.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2015.5 (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.decnullableindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR2Gaia DR2 identification numbermeta.idRA_ICRSGaia DR2 right ascension (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRSGaia DR2 declination (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainRVRadial velocitykm/sphys.veloc;pos.heliocentricinte_RVUncertainty on the radial velocitykm/sstat.errorintrrmin? Minimum distance from the Galactic centre in cylindrical coordinateskpcpos.distance;stat.mindoublenullablerrmax? Maximum distance from the Galactic centre in cylindrical coordinateskpcpos.distance;stat.maxdoublenullablezmax? Maximum distance from the Galactic planekpcpos.distance;stat.maxdoublenullablermin? Minimum distance from the Galactic centre in spherical coordinateskpcpos.distance;stat.mindoublenullablermax? Maximum distance from the Galactic centre in spherical coordinateskpcpos.distance;stat.maxdoublenullableJ/A+A/638/A122/abundAbundancesA(TiI)? Ti abundance from TiI linesphys.abundfloatnullableo_TiI? Number of TiI lines usedmeta.numberintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarName of the starmeta.id;meta.maincharTeffEffective temperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloatvtMicro-turbulencekm/sphys.veloc.microTurbfloat[Fe/H]Metallicity [Fe/H] with A(Fe)sun=7.75phys.abund.Zfloatl_A(C)Upper limit flag on A(C) from the G-bandmeta.code.errorcharA(C)C abundance from the G-bandphys.abundfloatu_A(C)Uncertainty flag on A(C)meta.code.errorcharl_A(N)Upper limit foag on A(N)meta.code.errorcharA(N)? N abundance from CN linesphys.abundfloatnullableu_A(N)Uncertainty flag on A(N)meta.code.errorcharA(Mg)Mg abundancephys.abundfloato_MGNumber of Mg lines usedmeta.numberints_Mgline-to-line scatter for Mgstat.errorfloatA(CaI)? Ca abundance from CaI linesphys.abundfloatnullableo_CaI? Number of CaI lines usedmeta.numberintnullables_CaI? Line-to-line scatter for CaI linesstat.errorfloatnullables_TiI? Line-to-line scatter for TiI linesstat.errorfloatnullableA(TiII)? Ti abundance from TiII linesphys.abundfloatnullableo_TiII? Number of TiII lines usedmeta.numberintnullables_TiII? Line-to-line scatter for TiII linesstat.errorfloatnullableA(FeI)Fe abundance from FeI linesphys.abundfloato_FeINumber of FeI lines usedmeta.numberints_FeILine-to-line scatter for FeI linesstat.errorfloatA(FeII)? Fe abundance from FeII linesphys.abundfloatnullableA(Ni)? Ni abundancephys.abundfloatnullableA(Sr)? Sr abundancephys.abundfloatnullableA(BaII)? Ba abundance from BaII linesphys.abundfloatnullableo_BaII? number of BaII lines usedmeta.numberintnullablee_BaII? line-to-line scatter for BaII linesstat.errorfloatnullableA(CaII-K)? Ca abundance from the CaII-K linephys.abundfloatnullable