J/ApJ/819/135ivo://CDS.VizieR/J/ApJ/819/135doi:10.26093/cds/vizier.18190135CDSKirby E.N.Guhathakurta P.Zhang A.J.Hong J.Guo M.Guo R.,Cohen J.G.Cunha K.2018-09-06T07:27:47Z2016-06-22T08:29:38ZCDS support team

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

cds-question@unistra.frglobular-star-clusterschemical-abundancesgiant-starsAlthough red giants deplete lithium on their surfaces, some giants are Li-rich. Intermediate-mass asymptotic giant branch (AGB) stars can generate Li through the Cameron-Fowler conveyor, but the existence of Li-rich, low-mass red giant branch (RGB) stars is puzzling. Globular clusters are the best sites to examine this phenomenon because it is straightforward to determine membership in the cluster and to identify the evolutionary state of each star. In 72 hours of Keck/DEIMOS exposures in 25 clusters, we found four Li-rich RGB and two Li-rich AGB stars. There were 1696 RGB and 125 AGB stars with measurements or upper limits consistent with normal abundances of Li. Hence, the frequency of Li-richness in globular clusters is (0.2+/-0.1)% for the RGB, (1.6+/-1.1)% for the AGB, and (0.3+/-0.1)% for all giants. Because the Li-rich RGB stars are on the lower RGB, Li self-generation mechanisms proposed to occur at the luminosity function bump or He core flash cannot explain these four lower RGB stars. We propose the following origin for Li enrichment: (1) All luminous giants experience a brief phase of Li enrichment at the He core flash. (2) All post-RGB stars with binary companions on the lower RGB will engage in mass transfer. This scenario predicts that 0.1% of lower RGB stars will appear Li-rich due to mass transfer from a recently Li-enhanced companion. This frequency is at the lower end of our confidence interval.2016ApJ...819..135Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/819/135CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)VII/202 : Globular Clusters in the Milky Way (Harris, 1997)J/MNRAS/449/4038 : Li abundance of giants in 3 GCs (D'Orazi+, 2015)J/A+A/554/A96 : Spectra of LiI(670.8nm) line in metal-poor stars (Lind+, 2013)J/A+A/551/A36 : Metallicity of M dwarfs. III. (Neves+, 2013)J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)J/A+A/539/A157 : Li and Na in globular cluster M4 (Monaco+, 2012)J/A+A/538/A36 : Lithium abundances of bulge RGB stars (Lebzelter+, 2012)J/ApJS/191/352 : Abundances in stars of MW dwarf satellites (Kirby+, 2010)J/MNRAS/403/1413 : Updated stellar yields from AGB models (Karakas, 2010)J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009)J/A+A/504/829 : Spectroscopic survey of youngest field stars (Guillout+, 2009)J/A+A/503/545 : Equivalent widths of Li, Na, Fe, Ca in NGC 6397 (Lind+, 2009)J/A+A/503/541 : Li in late-type stars non-LTE calculations (Lind+, 2009)J/ApJ/682/1217 : Abundances in red giants in 7 globular clusters (Kirby+, 2008)J/A+A/469/529 : UBVI photometry of NGC 6864 (Kravtsov+, 2007)J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)J/PASP/117/37 : BVRI photometry in NGC 2419, Pal 4, and Pal 14 (Saha+, 2005)J/A+A/415/1153 : [Fe/H] for 98 extra-solar planet-host stars (Santos+, 2004)J/AJ/124/915 : VI photometry of NGC 5634 (Bellazzini+, 2002)J/AJ/122/2569 : VI photometry of NGC 288, 362 and 1851 (Bellazzini+, 2001)J/A+A/371/943 : Lithium abundances for 185 main-sequence stars (Chen+, 2001)J/AJ/121/916 : HST obs. of NGC 2298, 5897, 6535, and 6626 (Testa+, 2001)J/A+AS/144/5 : Nearby GCs photometric catalog (Rosenberg+, 2000)J/A+A/352/117 : Galactic lithium evolution revisited (Romano+, 1999)J/ApJ/518/262 : CCD VIc Photometry of M30 Stars (Sandquist+, 1999)J/AJ/108/555 : BVI photometry in globular cluster M68 (Walker, 1994)J/ApJ/420/612 : Proper motions + radial velocities in M22 (Peterson+ 1994)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/819/135https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/819/135http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/819/135https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/819/135https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/819/135http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/819/135GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/819/135/table1 (Globular clusters observed)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/819/135/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/819/135/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/819/135/table1?GETtext/xml+votable180.050000true13.1875-26.58250.005555555555555556Cone search capability for table J/ApJ/819/135/table4 (Stellar properties and Lithium abundances; updated version sent by the author)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/819/135/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/819/135/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/819/135/table4?GETtext/xml+votable180.050000true189.8893333-26.72036110.0055555555555555566/1133 6389 9436 9664 9666 10008 10336 12405 12531 12943 14489 16647 17121 19091 19097 20001 21017 24843 25873 27975 27981 27984 27986 28966 28967 28972 28973 31416 31417 31722 31723 44427 44452 48434 48440 48698https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/819/135?format=asciidefaultJ/ApJ/819/135/table1Globular clusters observedOIDMessier numbermeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGCGlobular cluster identifiermeta.id;meta.maincharRAJ2000Hour of Right Ascension (J2000) (2)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000) (2)pos.eq.dec;meta.mainr_GCReference for GC catalog (3)meta.ref;pos.framecharNsmeta.numberintnullableNobsmeta.numberintnullableSimbadSimbad column added by the CDSmeta.ref.urlcharNEDNED column added by the CDSmeta.ref.urlcharJ/ApJ/819/135/table4Stellar properties and Lithium abundances; updated version sent by the authorrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintOIDMessier globular cluster identifiermeta.id.parentcharGCGlobular cluster identifiermeta.id.parentcharNameStar namemeta.id;meta.maincharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainBranch"RGB" or "AGB" starsrc.classcharVmag[11.9/21.9] Extinction-corrected apparent V magnitudemagphot.mag;em.opt.VfloatB-V[0.2/1.9]? Reddening-corrected B-V color indexmagphot.color;em.opt.B;em.opt.VfloatnullableV-I[0.4/1.8]? Reddening-corrected V-I color indexmagphot.color;em.opt.V;em.opt.IfloatnullableVMag[-2.9/3.4] Extinction-corrected absolute V magnitudemagphys.magAbs;em.opt.VfloatTeff[3852/6727] Effective temperatureKphys.temperature.effectiveintlog(g)[0.2/3.6] Log surface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H][-3.1/-0.3] Log Iron abundance relative to the Sunlog(Sun)phys.abund.Fefloate_[Fe/H][0.1/1] Uncertainty in [Fe/H]log(Sun)stat.error;phys.abund.Fefloatl_A(Li)Upper limit flag for A(Li)meta.code.errorcharA(Li)[-1.4/7.5] Lithium abundancephys.abundfloate_A(Li)[0.1/0.4]? Uncertainty in A(Li)stat.errorfloatnullableJ/ApJ/819/135/table2DEIMOS observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGCGlobular cluster identifiermeta.id;meta.maincharOIDMessier numbermeta.idcharSlitSlitmask namemeta.id;obscharf_Slit[a] a: Observations by Simon & Geha (2007ApJ...670..313S)meta.codecharNt[22/177]? Number of targets on the slitmaskmeta.idintnullableDateUT date of observationtime.epoch;obsnullableAirmass[1/2.1]? Airmassobs.airMassfloatnullableSeeing[0.5/1.2]? Seeingarcsecinstr.obsty.seeingfloatnullableNx[1/5]? Number of exposuresmeta.numberintnullableExp[300/7200]? Total exposure timestime.duration;obs.exposureintnullableJ/ApJ/819/135/table3Line listrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[6697.1/6717] Wavelength in air0.1nmem.wldoubleSpeciesElement or molecule namephys.atmol.elementcharState? Ionization statephys.atmol.ionStagecharEP[0/14.5] Excitation potentialeVphys.atmol.excitationfloatlog(gf)[-5.1/0.4] Oscillator strengthphys.atmol.oscStrengthfloat