J/A+A/475/539ivo://CDS.VizieR/J/A+A/475/539doi:10.26093/cds/vizier.34750539CDSPrisinzano L.Randich S.2017-12-22T05:32:23Z2007-12-03T15:57:02ZCDS support team

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

cds-question@unistra.fropen-star-clustersvisible-astronomybroad-band-photometrychemical-abundancesOld open clusters are very useful targets to investigate mechanisms responsible for lithium (Li) depletion during the main sequence. Comparison of the Li abundances in clusters of different age allows us to understand the efficiency of the Li destruction process. To determine the membership and Li abundance in a sample of candidate members of the open cluster NGC 3960 (age ~1Gyr), aiming to fill the gap between 0.6 and 2Gyr in the empirical description of the behavior of the average Li abundance as a function of the stellar age. We use VLT/FLAMES Giraffe spectra to determine the radial velocities and thus the membership of a sample of 113 photometrically selected candidate cluster members. From the analysis of the Li line we derive Li abundances for both cluster members and non-members. 39 stars have radial velocities consistent with membership, with an expected fraction of contaminating field stars of about 20%. Li is detected in 29 of the radial velocity members; we consider these stars as cluster members, while we make the reasonable assumption that the remaining 10 radial velocity members without Li are among the contaminating stars. Li abundances of the stars hotter than about 6000K are similar to those of stars in the Hyades, while they are slightly smaller for cooler stars. This confirms that NGC 3960 is older than the Hyades. The average Li abundance of stars cooler than about 6000K indicates that the Li Pop. I plateau might start at ~1Gyr, rather than 2Gyr, which is the upper limit previously derived in the literature. We also find that the fraction of field stars with high Li abundance (>1.5) is about one third of the whole sample, which is in agreement with previous estimates. The fraction of contaminating field stars is consistent with that previously derived by us from photometry.2007A&A...475..539Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/475/539CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/417/945 : BVI & JHK photometry of NGC 3960 (Prisinzano+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/475/539https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/475/539http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/475/539https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/475/539https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/475/539http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/475/539GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/475/539/table4 (Stellar parameters for the NGC 3960 stars observed with GIRAFFE)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/475/539/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/475/539/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/475/539/table4?GETtext/xml+votable180.050000true177.6164092-55.64477920.0055555555555555566/37970-37971https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/475/539?format=asciiOpticaldefaultJ/A+A/475/539/table4Stellar parameters for the NGC 3960 stars observed with GIRAFFENspSpectrum numbermeta.idintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintP04Identification number of Prisinzano et al., Cat. <J/A+A/417/945>, Cl* NGC 3960 PMS NNNNNN in Simbad (1)meta.id;meta.mainintNameGiraffe identification name, OC21-MNNNmeta.idcharRAJ2000Right ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainVmagV magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.VfloatBmagB magnitudemagphot.mag;em.opt.Bfloate_Bmagrms uncertainty on Bmagmagstat.error;phot.mag;em.opt.BfloatV0magV magnitude corrected for differential reddeningmagphot.mag.reddFree;em.opt.VfloatB0magB magnitude corrected for differential reddeningmagphot.mag;em.opt.BfloatRVRadial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.errorfloatMmb[0/2] Membership flag based on RV: 0=non-member, 1=member, 2=binarymeta.code.memberintTeffEffective temperature computed for the (B-V)0 colour index, corrected for differential reddeningKphys.temperature.effective;meta.modelledinte_Teffrms uncertainty on TeffKstat.error;phys.temperature.effectiveintl_EW(Li)Limit flag on EW(Li)meta.code.errorcharEW(Li)? Li equivalent width (in m{AA})0.1pmspect.line.eqWidthintnullablee_EW(Li)? rms uncertainty on EW(Li)0.1pmstat.errorintnullablel_A(Li)LTELimit flag on A(Li)LTEmeta.code.errorcharA(Li)LTE? LTE Li abundance (H=12, LTE model)phys.abundfloatnullablel_A(Li)NLTELimit flag on A(Li)NLTEmeta.code.errorcharA(Li)NLTE? NLTE Li abundance (H=12, non-LTE model)phys.abundfloatnullablee_A(Li)NLTE? rms uncertainty on A(Li)NLTEstat.errorfloatnullableSimbadSimbad column added by the CDSchar