J/A+A/471/795ivo://CDS.VizieR/J/A+A/471/795doi:10.26093/cds/vizier.34710795CDSLi Z.Han Z.2017-12-06T07:37:54Z2007-11-04T16:40:09ZCDS support team

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

cds-question@unistra.frstellar-populationsstellar-evolutionary-modelsTwo important stellar-population parameters (age and metallicity) of the dominant stellar populations (DSPs) of galaxies are usually estimated by comparing the observed absorption line indices or colors to predictions of some simple stellar population models. However, some studies show that there is actually recent star formation in galaxies, including early type ones. This suggests that we may not be obtaining accurate the two stellar-population parameters for the DSPs of galaxies. This is obvious when we estimate the two parameters by colors, because the youngest populations dominate the light and make the fitted stellar populations younger and richer in metal. We study how young populations (YSPs) in composite stellar populations (CSPs) affect the colors of star systems and to analyze how the stellar ages and metallicities derived from colors possibly deviate from those of the DSPs. It is found that the age and mass fraction of a YSP affect colors of a mixed star system significantly, but the former is stronger. In addition, our results show that the stellar ages and metallicities derived directly from a pair of colors are about 2.14Gyr younger, while 0.0027 more metal rich on average than those of the DSPs of composite stellar systems. Some possible distributions of the differences between stellar-population parameters determined by colors and those of DSPs of CSPs are presented. The possible distributions of the differences between colors of CSPs and those of their DSPs are also shown. Stellar ages and metallicities measured by colors and line-strength indices are compared in the work, with a sample of 18 galaxies. Furthermore, the YSPs may affect the fundamental plane and Kormendy relation of early type galaxies.2007A&A...471..795Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/471/795CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/471/795https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/471/795http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/471/795https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/471/795https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/471/795http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/471/795GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/471/795/comp (Two colors, two line-strength indices, and the results fitted by SSPs, for 18 galaxies (observational data are selected from a few sources listed in our paper))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/471/795/comp?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/471/795/comp?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/471/795/comp?GETtext/xml+votable180.050000true5.295791722.356750.0055555555555555566/5599 7225 7287 11824 13162 13401 19442 19611 19900 26055 26285 26362 27255 27515 27604 28038 28524 28653https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/471/795?format=asciidefaultJ/A+A/471/795/devDeviations in stellar ages and metallicities measured from color pairsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintdelta(Age)1Deviation in stellar age calculated by (B-V) and (V-K)Gyrstat.fit;arith.zpdoubledelta(Z)1Deviation in stellar metallicity calculated by (B-V) and (V-K)stat.fit;arith.zpfloatdelta(Age)2Deviation in stellar age calculated by (B-V) and (B-K)Gyrstat.fit;arith.zpdoubledelta(Z)2Deviation in stellar metallicity calculated by (B-V) and (B-K)stat.fit;arith.zpfloatdelta(Age)3Deviation in stellar age calculated by (B-V) and (I-H)Gyrstat.fit;arith.zpdoubledelta(Z)3Deviation in stellar metallicity calculated by (B-V) and (I-H)stat.fit;arith.zpfloatJ/A+A/471/795/compTwo colors, two line-strength indices, and the results fitted by SSPs, for 18 galaxies (observational data are selected from a few sources listed in our paper)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameGalaxy namemeta.id;meta.maincharHbetaThe Hbeta Lick/IDS index0.1nmspect.index;em.line.Hbetafloat[MgFe]Composite index of Mgb, Fe5270 and Fe5335 (1)0.1nmspect.indexfloatlog(Age)mLogarithmic stellar age measured from H{beta} and [MgFe] line-strength indiceslog(yr)time.agefloat[Z/H]mStellar metallicity measured from H{beta} and [MgFe] line-strength indiceslog(Sun)phys.abund.Fefloat(B-V)(B-V) color indexmagphot.color;em.opt.B;em.opt.Vfloat(B-K)(B-K) color indexmagphot.color;em.opt.B;em.IR.Kfloatlog(Age)pLogarithmic stellar age measured from (B-V) and (B-K) color indiceslog(yr)time.agefloat[Z/H]pStellar metallicity measured from (B-V) and (B-K) color indiceslog(Sun)phys.abund.FefloatSimbadSimbad column added by the CDScharNEDSimbad column added by the CDSchar_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