J/AJ/157/154ivo://CDS.VizieR/J/AJ/157/154doi:10.26093/cds/vizier.51570154CDSGerber J.M.Briley M.M.Smith G.H.2021-03-02T09:44:14Z2019-08-06T06:50:47ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyglobular-star-clustersgiant-starschemical-abundancesphotometryvisible-astronomyeffective-temperatureAmong stars in Galactic globular clusters the carbon abundance tends to decrease with increasing luminosity on the upper red giant branch, particularly within the lowest metallicity clusters. While such a phenomena is not predicted by canonical models of stellar interiors and evolution, it is widely held to be the result of some extra mixing operating during red giant branch ascent which transports material exposed to the CN(O)-cycle across the radiative zone in the stellar interior and into the base of the convective envelope, whereupon it is brought rapidly to the stellar surface. Here we present measurements of [C/Fe] abundances among 67 red giants in 19 globular clusters within the Milky Way. Building on the work of Martell et al. (2008AJ....136.2522M), we have concentrated on giants with absolute magnitudes of M_V_~-1.5 within clusters encompassing a range of metallicity (-2.4<[Fe/H]<-0.3). The Kitt Peak National Observatory (KPNO) 4 m and Southern Astrophysical Research (SOAR) 4.1 m telescopes were used to obtain spectra covering the {lambda}4300 CH and {lambda}3883 CN bands. The CH absorption features in these spectra have been analyzed via synthetic spectra in order to obtain [C/Fe] abundances. These abundances and the luminosities of the observed stars were used to infer the rate at which C abundances change with time during upper red giant branch evolution (i.e., the mixing efficiency). By establishing rates over a range of metallicity, the dependence of deep mixing on metallicity is explored. We find that the inferred carbon depletion rate decreases as a function of metallicity, although our results are dependent on the initial [C/Fe] composition assumed for each star.2019AJ....157..154Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/157/154CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/195 : Globular Clusters in the Milky Way (Harris, 1996)III/221 : Catalogue of [Fe/H] of F, G, K stars (Cayrel de Strobel+, 2001)J/AJ/113/26 : Photometry of young globular clusters (Sarajedini+ 1997)J/AJ/116/1775 : BV photometry of M53 (Rey+, 1998)J/ApJ/611/323 : BVI photometry of M5 giant branch stars (Sandquist+, 2004)J/AJ/135/1117 : Spectroscopic study of red giants in M15 (Meszaros+, 2008)J/ApJ/682/1217 : Abundances in red giants in 7 globular clustersJ/A+A/505/117 : Abundances of red giants in 15 globular clustersJ/A+A/505/139 : Abundances of red giants in 17 globular clustersJ/A+A/507/803 : VI photometry of new M53 variables (Dekany+, 2009)J/AJ/137/4282 : Red giant stars in clusters. II. M13 and M92J/AJ/149/153 : Abundances of red giants in 10 globular clustersJ/A+A/590/A9 : RGB stars in Galactic GC stellar parameters (Dias+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/157/154https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/157/154http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/157/154https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/157/154https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/157/154http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/157/154GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/157/154/clusters (List of globular clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/157/154/clusters?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/157/154/clusters?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/157/154/clusters?GETtext/xml+votable180.050000true289.433-34.65772220.005555555555555556Cone search capability for table J/AJ/157/154/table1 (Abundances for program stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/157/154/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/157/154/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/157/154/table1?GETtext/xml+votable180.050000true289.4332083-34.65369440.0055555555555555566/9436 9664 9666 10336 10337 12405 12425 14489 17121 26028 27975 27981 27986 28067 30769 31019 31115 31416 31417 41304 47825 47828 47916 48434 48952https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/157/154?format=asciiOpticaldefaultJ/AJ/157/154/clustersList of globular clustersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGCGlobular cluster identifiermeta.id.parentcharNsNumber of program stars in Table 1meta.numberintnullableRAJ2000Simbad Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Simbad Degree of Declination (J2000)pos.eq.dec;meta.mainSimbadSimbad column added by the CDSmeta.ref.urlcharJ/AJ/157/154/table1Abundances for program starsGCGlobular cluster identifier (1)meta.id.parentcharf_[O/Fe]Flag on [O/Fe] (3)meta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintONameOther globular cluster identifiermeta.idcharIDStellar identifier(s)meta.id;meta.mainchar2MASS2MASS identifier (JHHMMSSss-DDMMSSs)meta.idchar[Fe/H][-2.37/-0.32] Metallicitylog(Sun)phys.abund.ZfloatVmag[12.58/15.85] Apparent V band magnitudemagphot.mag;em.opt.VfloatVMag[-2.03/-1.11] Absolute V band magnitudemagphys.magAbsfloatTeff[3942/4748] Effective temperatureKphys.temperature.effectiveintlog(g)[0.76/1.53] Log surface gravitylog(cm.s**-2)phys.gravityfloatS(3839)[-0.15/0.483] The CN index S(3839)spect.indexfloatI(CH)[0.142/0.476] The I(CH) absorption indexspect.indexfloat[C/Fe][-0.9/-0.14] Log C/Fe abundance ratio (2)log(Sun)phys.abund;arith.ratiofloate_[C/Fe][0.16/0.37] Uncertainty in [C/Fe]log(Sun)stat.error;phys.abundfloat[N/Fe][0.6/1.76] Log N/Fe abundance ratio (2)log(Sun)phys.abund;arith.ratiofloate_[N/Fe][0.09/0.35] Uncertainty in [N/Fe]log(Sun)stat.error;phys.abundfloat[O/Fe][-0.11/0.61]? Log O/Fe abundance ratio (2)log(Sun)phys.abundfloatnullableTelTelescope (4)meta.id;instr.telcharSimbadSimbad column added by the CDSmeta.ref.urlchar_RAPositions from 2MASS names (right ascension part)degpos.eq.ra;meta.main_DEPositions from 2MASS names (declination part)degpos.eq.dec;meta.main