J/A+A/464/939ivo://CDS.VizieR/J/A+A/464/939doi:10.26093/cds/vizier.34640939CDSCarretta E.Bragaglia A.Gratton R.G.Catanzaro G.Leone F.Sabbi E.,Cassisi S.Claudi R.D'Antona F.Francois P.James G.Piotto G.2017-06-21T08:22:09Z2009-09-17T16:34:17ZCDS support team

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

cds-question@unistra.frglobular-star-clusterspopulation-ii-starschemical-abundancesradial-velocityWe used the multifiber spectrograph FLAMES on the ESO Very Large Telescope UT2 to derive atmospheric parameters, metallicities and abundances of O and Na for 79 red giant stars in the Galactic globular cluster NGC 6218 (M 12). We analyzed stars in the magnitude range from about 1mag below the bump to the tip of the Red Giant Branch. The average metallicity we derive is [Fe/H]=-1.31+/-0.004+/-0.028dex (random and systematic errors, respectively), with a very small star-to-star scatter (rms=0.033dex), from moderately high-resolution Giraffe spectra. This is the first extensive spectroscopic abundance analysis in this cluster. Our results indicate that NGC 6218 is very homogeneous as far as heavy elements are concerned. On the other hand, light elements involved in the well known proton-capture reactions of H-burning at high temperature, such as O and Na, show large variations, anticorrelated with each other, at all luminosities along the red giant branch. The conclusion is that the Na-O anticorrelation must be established in early times at the cluster formation. We interpret the variation of Na found near the RGB-bump as the effect of two distinct populations having different bump luminosities, as predicted for different He content. To our knowledge, NGC 6218 is the first GC where such a signature has been spectroscopically detected, when combined with consistent and homogeneous data obtained for NGC 6752 to gain in statistical significance.2007A&A...464..939Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/464/939CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/455/271 : Abundances of red giants in NGC 6441 (Gratton+, 2006)J/A+A/464/927 : Abundances of red giants in NGC 6752 (Carreta+, 2007)J/A+A/464/953 : Abundances of red giants in NGC 6441 (Gratton+, 2007)J/A+A/464/981 : Abundances of red giants in NGC 6388 (Carreta+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/464/939https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/464/939http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/464/939https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/464/939https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/464/939http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/464/939GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/464/939/table2 (Identification, equatorial coordinates, BVJK magnitudes, heliocentric radial velocity)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/464/939/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/464/939/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/464/939/table2?GETtext/xml+votable180.050000true251.9351289-1.85834070.0055555555555555566/311158.650015785639275e-20 1.7003137259100215e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/464/939?format=asciiOpticaldefaultJ/A+A/464/939/table2Identification, equatorial coordinates, BVJK magnitudes, heliocentric radial velocityrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/92] Sequential numbermeta.recordintIDIdentification number (Sabbi et al., 2006, in prep.)meta.id;meta.mainintprimaryRAJ2000Right ascension (J2000.0)degpos.eq.ra;meta.mainDEJ2000Declination (J2000.0)degpos.eq.dec;meta.mainBmagJohnson B magnitudemagphot.mag;em.opt.BfloatVmagJohnson V magnitudemagphot.mag;em.opt.VfloatJmag2MASS J magnitudemagphot.mag;em.IR.JfloatKmag2MASS K magnitudemagphot.mag;em.IR.KfloatRV11? Heliocentric radial velocity for grating HR11km/sspect.dopplerVeloc;pos.heliocentricfloatnullableRV13? Heliocentric radial velocity for grating HR13km/sspect.dopplerVeloc;pos.heliocentricfloatnullableFlag[*] *: stars not used in analysismeta.code.errorcharMem[NM? ] Non member (NM) or doubtful member (NM?)meta.code.membercharASimbad column added by the CDSmeta.ref.urlcharJ/A+A/464/939/abundAtmospheric parameters, iron, O and Na abundancesgr[1/3]? Grating used (1)meta.id;instrintnullableo_O? Number of lines of Ometa.numberintnullable[O/Fe]? Average [O/Fe]log(Sun)phys.abundfloatnullablee_[O/Fe]? rms uncertainty on [O/Fe]log(Sun)stat.error;phys.abundfloatnullableo_Na? Number of lines of Nameta.numberintnullable[Na/Fe]? Average [Na/Fe]log(Sun)phys.abundfloatnullablee_[Na/Fe]? rms uncertainty on [Na/Fe]log(Sun)stat.error;phys.abundfloatnullablel_O[0/1]? Flag for measure/limit for O (2)meta.code.errorintnullableEWsAll Equivalent Width for this starmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification number (Sabbi et al., 2006, in prep.)meta.id;meta.mainintTeffEffective temperatureKphys.temperature.effectiveintloggGravitylog(cm.s**-2)phys.gravityfloat[A/H]Metallicitylog(Sun)phys.abundfloatVtMicroturbulent velocitykm/sphys.velocfloato_FeINumber of lines of Fe Imeta.numberint[Fe/H]IAverage star [Fe/H]Ilog(Sun)meta.idfloate_[Fe/H]Irms uncertainty on [Fe/H]Ilog(Sun)stat.error;phys.abund.Fefloato_FeII? Number of lines of Fe IImeta.numberintnullable[Fe/H]II? Average star [Fe/H]IIlog(Sun)meta.idfloatnullablee_[Fe/H]II? rms uncertainty on [Fe/H]IIlog(Sun)stat.error;phys.abund.FefloatnullableJ/A+A/464/939/tableaEquivalent widths for 79 objectsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification number (Sabbi et al., 2006, in prep.)meta.id;meta.mainintlambdaWavelength0.1nmem.wlfloatEPExcitation potentialeVphys.atmol.excitationfloatloggfSurface gravitylog(cm.s**-2)phys.gravityfloatEWEquivalent width0.1pmspect.line.eqWidthfloat