J/A+AS/137/233ivo://CDS.VizieR/J/A+AS/137/233CDSBaume G.Vazquez R.A.Feinstein A.1999-06-28T16:25:30Z1999-06-28T16:24:39ZCDS support team

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

cds-question@unistra.frinfrared-photometryvisible-astronomyWide-band photometryopen-star-clustersCCD UBVI photometry in the field of the open cluster NGC 6231 was obtained for 1060 stars down to V=19mag. Memberships, reddening, distance and age of this cluster were investigated. Its lower sequence displays a notorious bend at V=13.5mag followed by a high number of faint stars showing a large magnitude spread at constant colour. This distribution of stars does not seem to be produced by a mere accumulation of field stars seen in the direction of the cluster but by a real star excess in the zone. The evidence suggests these stars are serious candidates to be cluster members caught in their way towards the ZAMS. Fitting them with pre main sequence isochrones an age spread of 10Myr is obtained. The luminosity and mass functions were found to be flat for -7.5<M_v_<1.5 and for 3 to 80M_{sun}_ respectively.1999A&AS..137..233Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+AS/137/233CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+AS/137/233https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+AS/137/233http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+AS/137/233https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+AS/137/233https://vizier.iucaa.in/viz-bin/votable?-source=J/A+AS/137/233http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+AS/137/233GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/A+AS/137/233/table1CCD photometric observations in NGC 6231recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqSequence numbermeta.id;meta.mainintXposX position (1)pixpos.cartesian.x;instr.detfloatYposY position (1)pixpos.cartesian.y;instr.detfloatVmagV magnitudemagphot.mag;em.opt.Vfloatu_Vmag[: ] Uncertainty flag on Vmag (2)meta.code.errorcharB-VB-V colour indexmagphot.color;em.opt.B;em.opt.Vfloatu_B-V[: ] Uncertainty flag on B-V (2)meta.code.errorcharU-B? U-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatnullableu_U-B[: ] Uncertainty flag on V-R (2)meta.code.errorcharV-I? V-I colour indexmagphot.color;em.opt.V;em.opt.Ifloatnullableu_V-I[: ] Uncertainty flag on V-I (2)meta.code.errorcharRemRemarks (3)meta.notechar