J/ApJ/791/107ivo://CDS.VizieR/J/ApJ/791/107doi:10.26093/cds/vizier.17910107CDSVillanova S.Geisler D.Gratton R.G.Cassisi S.2018-08-24T05:58:35Z2017-04-07T15:41:40ZCDS support team

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

cds-question@unistra.frglobular-star-clusterssupergiant-starshst-photometryeffective-temperaturemetallicitystellar-ages{omega} Centauri is a peculiar globular cluster formed by a complex stellar population. To investigate it, we studied 172 stars belonging to the five SGBs that we can identify in our photometry, in order to measure their [Fe/H] content as well as estimate their age dispersion and the age-metallicity relation. The first important result is that all of these SGBs have a distribution in metallicity with a spread that exceeds the observational errors and typically displays several peaks that indicate the presence of several subpopulations. We were able to identify at least six of them based on their mean [Fe/H] content. These metallicity-based subpopulations are seen to varying extents in each of the five SGBs. Taking advantage of the age sensitivity of the SGB, we showed that, first of all, at least half of the subpopulations have an age spread of at least 2 Gyr. Then, we obtained an age-metallicity relation that is the most complete to date for this cluster. Interpretation of the age-metallicity relation is not straightforward, but it is possible that the cluster (or what we can call its progenitor) was initially composed of two populations with different metallicities. Because of their age, it is very unlikely that the most metal-rich derives from the most metal-poor by some kind of chemical evolution process, so they can be assumed to be two independent primordial objects, or perhaps two separate parts of a single larger object, that merged in the past to form the present-day cluster.2014ApJ...791..107Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/791/107CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/445/503 : Radial velocities in Omega Cen (NGC5139) (Reijns+, 2006)J/ApJ/647/1075 : Age-metallicity relation of {omega} Cen (Stanford+, 2006)J/ApJ/663/296 : UBV(RI)c phot. of omega Cen (NGC5139) subgiantsJ/ApJ/722/1373 : {omega} Centauri giants abundances (Johnson+, 2010)J/MNRAS/427/1153 : Stellar parameters of giants in {omega} Cen (Simpson+, 2012)J/MNRAS/433/1892 : Abundances of 848 giants of {omega} Cen (Simpson+, 2013)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/791/107https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/791/107http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/791/107https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/791/107https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/791/107http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/791/107GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/791/107/table3 (Parameters of the observed stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/791/107/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/791/107/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/791/107/table3?GETtext/xml+votable180.050000true201.60166667-47.559166670.0055555555555555566/432273.0438195650391073e-19 4.75565502943315e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/791/107?format=asciidefaultJ/ApJ/791/107/table3Parameters of the observed starsSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDSGB identifier (SGB_A.NNN)meta.id;meta.maincharRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainF435WmagHST/ACS F435W band magnitudemagphot.mag;em.opt.BfloatF625WmagHST/ACS F625W band magnitudemagphot.mag;em.opt.RfloatTeffEffective temperatureKphys.temperature.effectiveintlog(g)Log surface gravitylog(cm.s**-2)phys.gravityfloatVTurbTurbulent velocitykm/sphys.veloc.microTurbfloat[Fe/H]Metallicityphys.abund.ZfloatRVelRadial velocitykm/sphys.veloc;pos.heliocentricfloatAgeAgeGyrtime.agefloat