J/A+A/655/A23ivo://CDS.VizieR/J/A+A/655/A23doi:10.26093/cds/vizier.36550023CDSMagrini L.Smiljanic R.Franciosini E.Pasquini L.Randich S.,Casali G.Viscasillas Vazquez C.Bragaglia A.Spina L.Biazzo K.,Tautvaisienne G.Masseron T.Van der Swaelmen M.Pancino E.,Jimenez-Esteban F.Guiglion G.Martell S.Bensby T.D'Orazi V.,Baratella M.Korn A.Jofre P.Gilmore G.Worley C.Hourihane A.,Gonneau A.Sacco G.G.Morbidelli L.2023-02-08T11:30:37Z2021-11-06T16:19:12ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyopen-star-clustersgiant-starschemical-abundancesIt has recently been suggested that all giant stars with masses below 2M_{sun}_ suffer an episode of surface lithium enrichment between the tip of the red giant branch (RGB) and the red clump (RC). We test if the above result can be confirmed in a sample of RC and RGB stars that are members of open clusters. We discuss Li abundances in six open clusters with ages between 1.5 and 4.9Gyr (turn-off masses between 1.1 and 1.7M_{sun}_). We compare these observations with the predictions of different models that include rotation-induced mixing, thermohaline instability, mixing induced by the first He flash, and energy losses by neutrino magnetic moment. In six clusters, we find close to 35% of RC stars have Li abundances that are similar or higher than those of upper RGB stars. This can be a sign of fresh Li production. Because of the extra-mixing episode connected to the luminosity bump, the expectation has been for RC stars to have systematically lower surface Li abundances. However, we cannot confirm that this possible Li production is ubiquitous. For about 65% of RC giants, we can only determine upper limits in abundances that could be hiding very low Li content. Our results indicate the possibility that Li is being produced in the RC, at levels that would not typically permit the classification of these the stars as Li rich. The determination of their carbon isotopic ratio would help to confirm that the RC giants have suffered extra mixing followed by subsequent Li enrichment. The Li abundances of the RC stars can be qualitatively explained by the models by using an additional mixing episode close to the He flash.2021A&A...655A..23Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/655/A23CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/651/A84 : Li abundance and mixing in giant stars (Magrini+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/655/A23https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/655/A23http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/655/A23https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/655/A23https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/655/A23http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/655/A23GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/655/A23/table2 (Red clump member stars of open clusters with 1M_{sun}_<=MMSTO<=1.8M_{sun}_ and -0.2<=[Fe/H]<=0.2)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/655/A23/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/655/A23/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/655/A23/table2?GETtext/xml+votable180.050000true116.7087083-4.60011110.005555555555555556Cone search capability for table J/A+A/655/A23/table3 (*RGB and RC member stars of the six open clusters of Table 1)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/655/A23/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/655/A23/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/655/A23/table3?GETtext/xml+votable180.050000true87.907958321.726250.0055555555555555566/4298 6149 14575 20562 21519 21529 21719 22216 22237 22239 23638 23745 24322 24330 24344-24345 41613 43034https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/655/A23?format=asciidefaultJ/A+A/655/A23/table2Red clump member stars of open clusters with 1M_{sun}_<=MMSTO<=1.8M_{sun}_ and -0.2<=[Fe/H]<=0.2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCNameCName (HHMMSSss+DDMMSSs)meta.id;meta.maincharClusterCluster namemeta.id.parentcharTeffEffective temperatureKphys.temperature.effectivefloate_TeffEffective temperature errorKstat.error;phys.temperature.effectivefloatloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggSurface gravity errorlog(cm.s**-2)stat.errorfloat[Fe/H]Metallicityphys.abund.ZfloatSimbadSimbad column added by the CDSmeta.ref.urlchare_[Fe/H]Metallicity errorstat.error;phys.abund.Fefloatl_A(Li)[0/1] Limt flag on A(Li) (1 for upper limit)meta.code.errorintA(Li)Lithium abundancephys.abundfloate_A(Li)? Lithium abundance errorstat.errorfloatnullablelogLum? Luminositylog(solLum)phys.luminosityfloatnullablee_logLumLuminosity errorlog(solLum)stat.errorfloatMSTOMSTO masssolMassphys.massfloat_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/A+A/655/A23/table3*RGB and RC member stars of the six open clusters of Table 1SimbadSimbad column added by the CDSmeta.ref.urlcharClusterCluster namemeta.id.parentcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCNameCName (HHMMSSss+DDMMSSs)meta.id;meta.maincharTeffEffective temperatureKphys.temperature.effectivefloate_TeffEffective temperature errorKstat.error;phys.temperature.effectivefloatloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggSurface gravity errorlog(cm.s**-2)stat.errorfloat[Fe/H]Metallicityphys.abund.Zfloate_[Fe/H]Metallicity errorstat.error;phys.abund.Fefloatl_A(Li)[0/1] Limt flag on A(Li) (1 for upper limit)meta.code.errorintA(Li)Lithium abundancephys.abundfloate_A(Li)? Lithium abundance errorstat.errorfloatnullablelogLumLuminositylog(solLum)phys.luminosityfloate_logLumLuminosity errorlog(solLum)stat.errorfloatMSTOMSTO masssolMassphys.massfloatPhasePhase (RC, LRGB, or URGB) (1)src.classchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main