J/PASP/110/1318ivo://CDS.VizieR/J/PASP/110/1318doi:10.26093/cds/vizier.61101318CDSGim M.Vandenberg D.A.Stetson P.B.Hesser J.E.Zurek D.R.2025-09-09T14:12:22Z2013-11-26T15:14:30ZCDS support team

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

cds-question@unistra.fropen-star-clustersccd-photometryinfrared-photometryvisible-astronomyphotometryA V, V-I-diagram for the intermediate-age open cluster NGC 7789 has been derived from CCD observations of more than 15,000 stars within ~18' of the cluster center. From the brightest giants and blue stragglers at V~11 to the faintest lower main-sequence stars that were observed (at V~21, M_V_~9), the color-magnitude diagram is well defined. A prominent clump of core helium-burning stars is evident at V=13.0, and the upper end of the main sequence shows a fairly pronounced curvature to the red, which is indicative of significant convective core overshooting. Indeed, comparisons with up-to-date stellar models show that it is not possible to explain the observed morphology in the vicinity of the turnoff unless the overshooting is quite extensive. Interestingly, if sufficient overshooting is assumed in order to match the main-sequence data, it is not possible to reproduce the cluster's extended giant branch unless the cluster age is at least 1.6 Gyr (assuming a metallicity in the range -0.2<=[FeMH]<=0.0). This, in turn, requires that the cluster have an apparent distance modulus m-M_V_<=12.2. Thus, sometime within the past few hundred million years, the ignition of helium burning in NGC 7789 has switched from a quiescent to an explosive ("flash") phenomenon, and the length of the cluster's red giant branch has been steadily increasing with the passage of time since then. From main-sequence fits to models that have been carefully normalized to the Sun, we infer a reddening 0.35<=E(V-I)<=0.38.1998PASP..110.1318Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/PASP/110/1318CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/295/101 : Variable stars in field of NGC 7789 (Jahn+, 1995)J/PASP/110/1172 : NGC 789 radial velocities (Gim+, 1998)J/A+A/431/933 : Abundances of NGC 7789 evolved stars (Tautvaisiene+, 2005)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/PASP/110/1318https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/PASP/110/1318http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/PASP/110/1318https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/PASP/110/1318https://vizier.iucaa.in/viz-bin/votable?-source=J/PASP/110/1318http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/PASP/110/1318GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/PASP/110/1318/table (VI photometry in the region of NGC 7789)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/PASP/110/1318/table?https://vizier.iucaa.in/viz-bin/conesearch/J/PASP/110/1318/table?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/PASP/110/1318/table?GETtext/xml+votable180.050000true358.761996156.71362610.0055555555555555566/14173 141753.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/PASP/110/1318?format=asciiOpticalInfrareddefaultJ/PASP/110/1318/tableVI photometry in the region of NGC 7789ID[1/15617] Sequential numbermeta.recordintprimaryXposX position (1)pixpos.cartesian.x;instr.detdoubleYposY position (1)pixpos.cartesian.y;instr.detdoubleVmagV magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.VfloatV-IV-I colour indexmagphot.color;em.opt.V;em.opt.Ifloate_V-Irms uncertainty on V-Imagstat.error;phot.color;em.opt.Vfloatchi[0.5/8.4] {chi} valuestat.fit.chi2floatSharp[-4/17] DAOPHOT sharpness parameter (<0 for extended, >0 for cosmic ray)stat.fit.paramfloatVarInd[-299/730] Variability indexsrc.var.indexdoubleNVNumber of measurements on V bandmeta.numberintNINumber of measurements on I bandmeta.numberint_RAPosition computed from a comparison with UCAC4 (I/322) ({sigma}=0.14'') (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from a comparison with UCAC4 (I/322) ({sigma}=0.14'') (declination part)degpos.eq.dec;meta.main