J/AJ/153/261ivo://CDS.VizieR/J/AJ/153/261doi:10.26093/cds/vizier.51530261CDSSong Y.-Y.Mateo M.Walker M.G.Roederer I.U.2019-03-08T14:58:59Z2019-03-08T14:18:23ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsgiant-starsmetallicityphotometryvisible-astronomyWe report new spectroscopic observations obtained with the Michigan/Magellan Fiber System of 308 red giants (RGs) located in two fields near the photometric center of the bar of the Large Magellanic Cloud. This sample consists of 131 stars observed in previous studies (in one field) and 177 newly observed stars (in the second field) selected specifically to more reliably establish the metallicity and age distributions of the bar. For each star, we measure its heliocentric line-of-sight velocity, surface gravity, and metallicity from its high-resolution spectrum (effective temperatures come from photometric colors). The spectroscopic Hertzsprung-Russell diagrams- modulo small offsets in surface gravities-reveal good agreement with model isochrones. The mean metallicity of the 177-RG sample is [Fe/H]=-0.76+/-0.02 with a metallicity dispersion {sigma}=0.28+/-0.03. The corresponding metallicity distribution-corrected for selection effects-is well fitted by two Gaussian components: one metal-rich with a mean -0.66+/-0.02 and a standard deviation 0.17+/-0.01, and the other metal-poor with -1.20+/-0.24 and 0.41+/-0.06. The metal-rich and metal-poor populations contain approximately 85% and 15% of stars, respectively. We also confirm that the velocity dispersion in the bar center decreases significantly from 31.2+/-4.3 to 18.7+/-1.9km/s with increasing metallicity over the range -2.09 to -0.38. Individual stellar masses are estimated using the spectroscopic surface gravities and the known luminosities. We find that lower mass, hence older, RGs have larger metallicity dispersion and lower mean metallicity than the higher-mass, younger RGs. The estimated masses, however, extend to implausibly low values (~0.1M_{sun}_), making it impossible to obtain an absolute age-metallicity or age distribution of the bar.2017AJ....153..261Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/153/261CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/117/238 : LMC extended catalog (Bica+, 1999)J/AJ/120/1808 : Stroemgren photometry in LMC disk (Cole+, 2000)J/A+AS/141/371 : Low-mass stars evolutionary tracks (Girardi+, 2000)J/AcA/50/307 : OGLE LMC BVI photometry (Udalski+, 2000)J/MNRAS/339/701 : Velocities and BR photometry in LMC (Zhao+, 2003)J/A+A/421/937 : Metal abundances of LMC RR Lyrae (Gratton+, 2004)J/AJ/129/1465 : Spectroscopy of red giants in the LMC bar (Cole+, 2005)J/AJ/135/836 : Calcium triplet index in LMC stars (Carrera+, 2008)J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)J/A+A/480/379 : Abundances of 59 red giants in LMC (Pompeia+, 2008)J/AJ/136/375 : Chemical composition of LMC red giants (Mucciarelli+, 2008)J/MNRAS/405/1770 : LMC red giants in E sequence (Nicholls+, 2010)J/AJ/142/61 : RGB stars in LMC outer disk (Carrera+, 2011)J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)J/ApJ/761/33 : Chemical properties of stars in the LMC disk (Lapenna+, 2012)J/A+A/560/A44 : Abundances of LMC bar & disk stars (Van der Swaelmen+, 2013)J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)J/ApJ/808/108 : M2FS stellar spectroscopy of Reticulum 2 (Walker+, 2015)J/MNRAS/448/2717 : Bayesian analysis of stellar spectra (Walker+, 2015)J/ApJ/817/40 : High-resolution NIR spectra of local giants (Feuillet+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/153/261https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/153/261http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/153/261https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/153/261https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/153/261http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/153/261GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/153/261/table2 (selected in the LMC bar)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/153/261/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/153/261/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/153/261/table2?GETtext/xml+votable180.050000true81.3615-70.04219440.0055555555555555566/33096 33097 33098https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/153/261?format=asciiOpticaldefaultJ/AJ/153/261/table2selected in the LMC barSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPDisplay the measured physical parameters for this star (link to Table 4)meta.ref.urlcharIDIdentifier, Field-Fiber (G1)meta.id;meta.maincharprimaryRAJ2000[5] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[69/70] Degree of Declination (J2000)pos.eq.dec;meta.mainVmag[16.5/18.5] V band magnitude (1)magphot.mag;em.opt.Vfloate_Vmag[0.003/0.1] Uncertainty in Vmagmagstat.error;phot.mag;em.opt.VfloatImag[15.2/17] I band magnitude (1)magphot.mag;em.opt.Ifloate_Imag[0.003/0.1] Uncertainty in Imagmagstat.error;phot.mag;em.opt.IfloatONameOther identifier (2)meta.idcharJ/AJ/153/261/table4*Stellar parameters of the in the LMC barvlos[175/344] Line-of-sight velocitykm/sphys.veloc;pos.heliocentricfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentifier, Field-Fiber (G1)meta.id;meta.maincharSN[5/25] Signal-to-noisestat.snrfloate_vlos[0.3/1] Uncertainty in vloskm/sstat.errorfloatTeff[4003/5199] Stellar effective temperatureKphys.temperature.effectiveinte_Teff[57/247] Uncertainty in TeffKstat.error;phys.temperature.effectiveintlogg[0.07/3.3] Stellar surface gravity, loglog(cm.s**-2)phys.gravityfloate_logg[0.06/0.5] Uncertainty in logglog(cm.s**-2)stat.errorfloat[Fe/H][-2.5/-0.3] Metallicityphys.abund.Zfloate_[Fe/H][0.04/0.2] Uncertainty in [Fe/H]stat.error;phys.abund.Fefloat