J/A+A/666/A58ivo://CDS.VizieR/J/A+A/666/A58doi:10.26093/cds/vizier.36660058CDSXylakis-Dornbusch T.Christlieb N.Lind K.Nordlander T.2022-11-13T17:09:40Z2022-10-11T08:19:19ZCDS support team

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

cds-question@unistra.frastronomical-modelsspectroscopyvisible-astronomyWe developed a metal-poor candidate selection method based on flux-ratios from the BP/RP Gaia spectra, using simulated synthetic spectra. We found a relation between the relative iron abundance and the flux-ratio of the Ca H&K region to that of the H{beta} line. This relation is temperature and surface gravity dependent, and it holds for stars with effective temperature 4800<=Teff<=6300K. We applied it to noisy simulated synthetic spectra and inferred [Fe/H] with an uncertainty {sigma}<=0.65dex for -3.0<=[Fe/H]<=0.5 and G=15-17mag, which is sufficient for reliably identifying stars at [Fe/H]<-2.0. We predict that by selecting stars with inferred [Fe/H]<=-2.5dex, we can retrieve 80% of the stars with [Fe/H]<=-3.0, and we have a success rate of about 50%, i.e. 1 in 2 stars we select has [Fe/H]<=-3.0. We do not take into account the effect of reddening, so our method should only be applied to stars which are located in regions of low extinction.2022A&A...666A..58Xhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/666/A58CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/666/A58https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/666/A58http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/666/A58https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/666/A58https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/666/A58http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/666/A58GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/666/A58/tablea1Flux-ratios and the respective astrophysical parameters used to construct the method in the papera/a[0/8210]meta.idintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintG/CaNIRGaia G to CaNIR flux ratiophot.flux;arith.ratiodoubleCaHK/HbetaCaHK/Hbeta flux ratiophot.flux;arith.ratiodoubleTeffEffective temperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H]Metallicityphys.abund.Zfloat[C/Fe]Abundance [C/Fe]phys.abundfloatJ/A+A/666/A58/m_coeffsCoefficients of the metal-poor star identification methodloggSurface gravitylog(cm.s**-2)phys.gravityfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordinta/a[0/50]meta.idintbb coefficientstat.fit.paramdoublecc coefficientstat.fit.paramdoubledd coefficientstat.fit.paramdoubleTeffEffective temperatureKphys.temperature.effectivefloat