J/A+A/534/A80ivo://CDS.VizieR/J/A+A/534/A80doi:10.26093/cds/vizier.35340080CDSHill V.Lecureur A.Gomez A.Zoccali M.Schultheis M.Babusiaux C.,Royer F.Barbuy B.Arenou F.Minniti D.Ortolani S.2017-09-19T14:20:49Z2011-10-05T13:47:12ZCDS support team

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

cds-question@unistra.frgiant-starsmetallicityinfrared-photometryvisible-astronomybroad-band-photometryWe seek to constrain the formation of the Galactic bulge by means of analysing the detailed chemical composition of a large sample of red clump stars in Baade's window. These stars were selected to minimise the contamination by other Galactic components, so they are good tracers of the bulge metallicity distribution in Baade's window, at least for stars more metal-rich than ~-1.5. We used an automatic procedure to measure [Fe/H] in a sample of 219 bulge red clump stars from R=20000 resolution spectra obtained with FLAMES/GIRAFFE at the VLT. The analysis was performed differentially with respect to the metal-rich local reference star MuLeo. For a subsample of 162 stars, we also derived [Mg/H] from spectral synthesis around the MgI triplet at 6319{AA}. The Fe and Mg metallicity distributions are both asymmetric with median values of +0.16 and +0.21, respectively. They show only a small proportion of stars at low metallicities, extending down to [Fe/H]=-1.1 or [Mg/H]=-0.7 The iron distribution is clearly bimodal, as revealed both by a deconvolution (from observational errors) and a Gaussian decomposition. The decomposition of the observed Fe and Mg metallicity distributions into Gaussian components yields two populations of equal sizes (50% each): a metal-poor component centred on [Fe/H]=-0.30 and [Mg/H]=-0.06 with a large dispersion and a narrow metal-rich component centred on [Fe/H]=+0.32 and [Mg/H]=+0.35. The metal-poor component shows high [Mg/Fe] ratios (around 0.3), while stars in the metal-rich component are found to have near solar ratios. Kinematical differences between the two components have also been found: the metal-poor component shows kinematics compatible with an old spheroid, while the metal-rich component is consistent with a population supporting a bar. In view of their chemical and kinematical properties, we suggest different formation scenarii for the two populations: a rapid formation time scale as an old spheroid for the metal-poor component (old bulge) and for the metal-rich component, a formation on a longer time scale driven by the evolution of the bar (pseudo-bulge).2011A&A...534A..80Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/534/A80CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)J/AcA/49/319 : OGLE UBVI phot. in Baade's Window (Paczynski+, 1999)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/534/A80https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/534/A80http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/534/A80https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/534/A80https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/534/A80http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/534/A80GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/534/A80/sample (Selected 220 red clump stars in Baade's Window data (tables 1-3 of the paper))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/534/A80/sample?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/534/A80/sample?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/534/A80/sample?GETtext/xml+votable180.050000true270.9596667-30.09222220.0055555555555555566/287781.1166583743361574e-19 6.118840631666147e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/534/A80?format=asciiOpticalInfrareddefaultJ/A+A/534/A80/sampleSelected 220 red clump stars in Baade's Window data (tables 1-3 of the paper)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar name (BWc-NNN)meta.id;meta.maincharOGLEOGLE identifier, BUL-SC45 NNNNNN, from Paczynski et al., 1999, Cat. J/AcA/49/319meta.idintUmagJohnson U magnitudemagphot.mag;em.opt.Ufloate_Umagrms uncertainty on Umagmagstat.error;phot.mag;em.opt.UfloatBmagJohnson B magnitudemagphot.mag;em.opt.Bfloate_Bmagrms uncertainty on Bmagmagstat.error;phot.mag;em.opt.BfloatVmagJohnson V magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.VfloatImagJohnson I magnitudemagphot.mag;em.opt.Ifloate_Imagrms uncertainty on Imagmagstat.error;phot.mag;em.opt.Ifloat2MASS2MASS identifiermeta.idcharJmag2MASS J magnitudemagphot.mag;em.IR.Jfloate_Jmagrms uncertainty on Jmagmagstat.error;phot.mag;em.IR.JfloatHmag2MASS H magnitudemagphot.mag;em.IR.Hfloate_Hmagrms uncertainty on Hmagmagstat.error;phot.mag;em.IR.HfloatKmag2MASS K magnitudemagphot.mag;em.IR.Kfloate_Kmagrms uncertainty on Kmagmagstat.error;phot.mag;em.IR.KfloatSimbadSimbad column added by the CDSmeta.refcharTeffEffective TemperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloatvtMicroturbulence velocitykm/sphys.veloc.microTurbfloat[Fe/H]Fe/H abundancelog(Sun)phys.abund.Fefloate_[Fe/H]Uncertainty on [Fe/H] (lower value)log(Sun)stat.error;phys.abund.FefloatE_[Fe/H]Uncertainty on [Fe/H] (upper value)log(Sun)stat.error;stat.maxfloat[Mg/H]? Mg/H abundancelog(Sun)phys.abundfloatnullablee_[Mg/H]? Uncertainty on [Mg/H] (lower value)log(Sun)stat.error;phys.abundfloatnullableE_[Mg/H]? Uncertainty on [Mg/H] (upper value)log(Sun)stat.error;stat.maxfloatnullablee_vtUncertainty on the microturbulence velocity (lower value)km/sstat.errorfloatE_[Fe/H]vtUncertainty on Fe (upper value) arising from the uncertainty on the microturbulence velocity (lower value)log(Sun)stat.error;stat.maxfloatE_TeffUncertainty on the effective temperature (upper value)Kstat.error;stat.maxintE_[Fe/H]TUncertainty on Fe (upper value) arising from the uncertainty on the effective temperature (upper value)log(Sun)stat.error;stat.maxfloatE_vtUncertainty on the microturbulence velocity (upper value)km/sstat.error;stat.maxfloate_[Fe/H]vtUncertainty on Fe (lower value) arising from the uncertainty on the microturbulence velocity (upper value)log(Sun)stat.error;phys.abund.Fefloate_TeffUncertainty on the effective temperature (lower value)(T)Kstat.error;phys.temperature.effectiveinte_[Fe/H]TUncertainty on Fe (lower value) arising from the uncertainty on the effective temperature (lower value)log(Sun)stat.error;phys.abund.Fefloat_RAPosition (as computed from Paczynski et al., 1999, Cat. J/AcA/49/319) (right ascension part)degpos.eq.ra;meta.main_DEPosition (as computed from Paczynski et al., 1999, Cat. J/AcA/49/319) (declination part)degpos.eq.dec;meta.main