J/ApJ/298/544ivo://CDS.VizieR/J/ApJ/298/544doi:10.26093/cds/vizier.12980544CDSStryker L.L.Da Costa G.S.Mould J.R.1997-12-09T19:45:45Z1997-12-09T20:45:41ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsglobular-star-clustersccd-photometryThe age of the SMC globular cluster NGC 121 is found from main-sequence isochrone fitting to be 12+/-2x10^9^yr if a distance modulus that assumes Mv=+0.6 for the field RR Lyrae variables near the cluster is used. If instead (m-M)o = 19.3, then the cluster age is 9+/-2x10^9^yr. The cluster is known to contain both RR Lyrae variables and a marginal carbon star; comparison with theoretical models indicates no significant inconsistencies in this joint occurrence at either modulus. The color-magnitude diagram for the nearby field also shows a faint, blue main-sequence turnoff and, in contrast to previous Magellanic Cloud field studies, the field lacks any evidence for the existence of a significant intermediate-age component. A new look at the chemical evolution of the Small Magellanic Cloud suggests that, unlike the Galaxy, where the rate of enrichment has been steady after the initial phase, the enrichment in the SMC remained small for a long interval before increasing rapidly sometime in the last 1-2x10^9^yr.1985ApJ...298..544Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/298/544CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/298/544https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/298/544http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/298/544https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/298/544https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/298/544http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/298/544GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/298/544/table1Photometry in NGC 121recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar identification numbermeta.id;meta.mainintB-RB-R color indexmagphot.color;em.opt.B;em.opt.RfloatRmagR magnitudemagphot.mag;em.opt.RfloatXposX position (1)pixpos.cartesian.x;instr.detfloatYposY position (1)pixpos.cartesian.y;instr.detfloatDB-R? November 18-20 B-R color index differencemagphot.color;arith.difffloatDRmag? November 18-20 R magnitude differencemagphot.mag;arith.difffloatJ/ApJ/298/544/table2Photometry in fieldrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar identification numbermeta.id;meta.mainintB-RB-R color indexmagphot.color;em.opt.B;em.opt.RfloatRmagR magnitudemagphot.mag;em.opt.RfloatXposX position (1)pixpos.cartesian.x;instr.detfloatYposY position (1)pixpos.cartesian.y;instr.detfloatDB-R? November 18-20 B-R color index differencemagphot.color;arith.difffloatDRmag? November 18-20 R magnitude differencemagphot.mag;arith.difffloat