J/A+A/650/A194ivo://CDS.VizieR/J/A+A/650/A194doi:10.26093/cds/vizier.36500194CDSGiribaldi R.E.da Silva A.R.Smiljanic R.Cornejo Espinoza D.2023-01-06T13:40:32Z2021-06-29T08:11:42ZCDS support team

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

cds-question@unistra.frchemically-peculiar-starseffective-temperaturestellar-massesmetallicitystellar-radiistellar-agesSeveral large stellar spectroscopic surveys are producing overwhelming amounts of data that can be used for determining stellar atmospheric parameters and chemical abundances. Nonetheless, the accuracy achieved in the derived astrophysical parameters is still insufficient, mainly because of the paucity of adequate calibrators, particularly in the metal-poor regime ([Fe/H]<=-1.0). Our aim is to increase the number of metal-poor stellar calibrators that have accurate parameters. Here, we introduce the Titans metal-poor reference stars: a sample of 41 dwarf and subgiant stars with accurate, but model-dependent, parameters. Effective temperatures (Teff) were derived by fitting observed H{alpha} profiles with synthetic lines computed using three dimensional (3D) hydrodynamic model atmospheres that take into account departures from the local thermodynamic equilibrium (non-LTE effects). Surface gravities (logg) were computed using evolutionary tracks and parallaxes from Gaia early-data release 3. The same methods recover the Teff values of the Gaia benchmark stars, which are mostly based on interferometric measurements, with a 1{sigma} dispersion of 50K. We assume this to be the accuracy of the H{alpha} profiles computed from 3D non-LTE models for metal-poor dwarfs and subgiants, although this is likely an upper-bound estimate dominated by the uncertainty of the standard Teff values. We achieved an internal precision typically between 30-40K, these errors dominated by instrumental effects. The final total uncertainty for the Teff values of the Titans are thus estimated to be of the order of 1%. The typical error for logg is 0.04dex. In addition, we identified a few members of Gaia-Enceladus, of Sequoia, and of the Helmi stream in our sample. These stars can pave the way for the accurate chemical characterization of these Galactic substructures. Using the Titans as reference, large stellar surveys will be able to improve the internal calibration of their astrophysical parameters. Ultimately, this sample will help users of data from Gaia and large surveys in reaching their goal of redefining our understanding of stars, stellar systems, and the Milky Way.2021A&A...650A.194Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/650/A194CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)J/A+A/598/A54 : Line list (Hansen+, 2017)J/ApJ/835/81 : Bright metal-poor stars from HES Survey. II. (Beers+, 2017)J/A+A/623/A72 : Hipparcos stars binarity from Gaia pm anomaly (Kervella+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/650/A194https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/650/A194http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/650/A194https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/650/A194https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/650/A194http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/650/A194GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/650/A194/table2 (Fundamental parameters and metallicities of the Titans)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/650/A194/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/650/A194/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/650/A194/table2?GETtext/xml+votable180.050000true112.671942824.08618030.0055555555555555566/373 4376 5195 6159 8999 12704 12793 17124 17509 17545 18887 23011 23015 23096 25385 26025 26284 26289 27176 27394 27857 28336 29765 30179 33831 35913 36084 36745 38072 38216 39446 39647 39692 40567 41259 42331 43445 43786 44281 44542 44653 46506 46828 47040 47147 48281 48719 487363.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/650/A194?format=asciidefaultJ/A+A/650/A194/table1*Atmospheric parameters of the Titans in the literaturerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar namemeta.id;meta.maincharn_Star[*] Note on Star (1)meta.notecharTeffEffective temperatureKphys.temperature.effectiveinte_Teff? Effective temperature errorKstat.error;phys.temperature.effectiveintnullableloggSurface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H]Metallicityphys.abund.ZfloatSourceSource of the parameters used to select the stars (2)meta.bibcharNSpectraNumber of spectra used in the H{alpha} line fittingmeta.numberintJ/A+A/650/A194/table2Fundamental parameters and metallicities of the TitansSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlag[G] G for metal-poor Gaia benchmark stars (1)meta.code.errorcharStarStar namemeta.id;meta.maincharn_Star[*] Note on Star (G1)meta.notecharTeffEffective temperatureKphys.temperature.effectiveinte_TeffEffective temperature error (3)Kstat.error;phys.temperature.effectiveintu_TeffUncertainty flag on Teff (4)meta.code.error;phys.temperature.effectivecharloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggSurface gravity errorlog(cm.s**-2)stat.errorfloatMMasssolMassphys.massfloate_MMass errorsolMassstat.errorfloatRRadiussolRadphys.size.radiusfloate_RRadius errorsolRadstat.errorfloatAgeAgeGyrtime.agefloate_AgeAge errorGyrstat.error;time.agefloat[FeI/H]Abundance [FeI/H]phys.abundfloat[FeII/H]Abundance [FeII/H]phys.abundfloatVmagApparent V magnitudemagphot.mag;em.opt.VfloatE(B-V)Colour excessmagphot.color.excessfloat_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/A+A/650/A194/table4Membership classification of the TitansplxGaia EDR3 parallaxmaspos.parallax.trigfloate_plxGaia EDR3 parallax errormasstat.error;pos.parallaxfloatHVHeliocentric velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_HVHeliocentric velocity errorkm/sstat.errorfloatMembMembership (2)meta.code.membercharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlag[G] G for metal-poor Gaia benchmark starsmeta.code.errorcharStarStar namemeta.id;meta.maincharn_Star[*] Note on Star (G1)meta.notechar