J/AJ/154/150ivo://CDS.VizieR/J/AJ/154/150doi:10.26093/cds/vizier.51540150CDSAn D.Lee Y.S.Jung J.InRey S.-C.Rhee J.Lee J.-W.Lee Y.-W.,Joe Y.H.2018-09-27T13:07:02Z2018-08-02T08:10:25ZCDS support team

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

cds-question@unistra.frglobular-star-clustersgiant-starsspectroscopychemical-abundanceseffective-temperatureradial-velocityWe present [Fe/H] and [Ca/Fe] of ~600 red giant branch (RGB) members of the globular cluster Omega Centauri ({omega} Cen). We collect medium-resolution (R~2000) spectra using the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory equipped with Hydra, the fiber-fed multi-object spectrograph. We demonstrate that blending of stellar light in optical fibers severely limits the accuracy of spectroscopic parameters in the crowded central region of the cluster. When photometric temperatures are taken in the spectroscopic analysis, our kinematically selected cluster members, excluding those that are strongly affected by flux from neighboring stars, include relatively fewer stars at intermediate metallicity ([Fe/H]~-1.5) than seen in the previous high-resolution survey for brighter giants in Johnson & Pilachowski (2010, J/ApJ/722/1373). As opposed to the trend of increasing [Ca/Fe] with [Fe/H] found by those authors, our [Ca/Fe] estimates, based on Ca II H & K measurements, show essentially the same mean [Ca/Fe] for most of the metal-poor and metal-intermediate populations in this cluster, suggesting that mass- or metallicity-dependent SN II yields may not be necessary in their proposed chemical evolution scenario. Metal-rich cluster members in our sample show a large spread in [Ca/Fe], and do not exhibit a clear bimodal distribution in [Ca/Fe]. We also do not find convincing evidence for a radial metallicity gradient among RGB stars in {omega} Cen.2017AJ....154..150Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/154/150CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/462/241 : Ca abundance for Omega Cen red giants (Norris+ 1996)J/AJ/127/958 : CCD BV photometry on Omega Cen (Rey+, 2004)J/MNRAS/357/265 : BVI photometry of omega Cen red giants (Sollima+, 2005)J/ApJ/661/L155 : Radial velocities RGB stars in omega Cen (Pancino+, 2007)J/ApJ/681/1505 : Abundances of red giants in {omega} Cen (Johnson+, 2008)J/MNRAS/396/2183 : Radial velocities of red giants in {omega} CenJ/ApJ/722/1373 : {omega} Centauri giants abundances (Johnson+, 2010)J/ApJ/731/64 : Spectroscopy of 300 RGBs in {omega} Cen (Marino+, 2011)J/MNRAS/416/L6 : AGB and RGB stars in {omega} Cen (McDonald+, 2011)J/MNRAS/427/1153 : Stellar parameters of giants in {omega} Cen (Simpson+, 2012)J/MNRAS/433/1892 : Abundances of 848 giants of {omega} Cen (Simpson+, 2013)J/ApJ/837/176 : Spectroscopic obs. of 2 red giant stars in omega Cenhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/154/150https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/154/150http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/154/150https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/154/150https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/154/150http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/154/150GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/154/150/table1 (Spectroscopic Properties of Stars in {omega} Cen)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/154/150/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/154/150/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/154/150/table1?GETtext/xml+votable180.050000true201.6434583-47.50677780.0055555555555555566/43225 43227 43228 432303.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/154/150?format=asciidefaultJ/AJ/154/150/table1Spectroscopic Properties of Stars in {omega} CenrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/712] Sequential running star identifiermeta.recordintRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainVmag[14.201/14.998] V band magnitude from Rey et al. 2004 (J/AJ/127/958)magphot.mag;em.opt.VfloatB-V[0.802/1.281] B-V color from Rey et al. 2004 (J/AJ/127/958)magphot.color;em.opt.B;em.opt.VfloatTeff[4601/5410] Adjusted IRFM (Infrared Flux Method) effective temperatureKphys.temperature.effectiveinte_Teff[0/107]? Uncertainty in TeffKstat.error;phys.temperature.effectiveintnullablelogg[0.5/4.04] Surface gravitylog(cm.s**-2)phys.gravityfloate_logg[0/1.49]? Uncertainty in logglog(cm.s**-2)stat.errorfloatnullable[Fe/H][-2.28/0.21] Metallicityphys.abund.Zfloate_[Fe/H][0/1.54]? Uncertainty in [Fe/H]stat.error;phys.abund.Fefloatnullable[Ca/Fe][-1.87/1.19] Calcium abundancephys.abundfloate_[Ca/Fe][0.01/0.72]? Uncertainty in [Ca/Fe]stat.error;phys.abundfloatnullableRV[-89.6/286.9]? Radial velocitykm/sphys.veloc;pos.heliocentricfloatnullablee_RV[0/60.4]? Uncertainty in RVkm/sstat.errorfloatnullableFneighb[0/0.98]? Fractional contribution of flux in B passband from neighboring starsphot.flux;arith.ratiofloatnullableNobs[1/3] Number of spectra with S/N>=52meta.numberintMem[mx] Cluster membership (1)meta.code.memberchar