J/AJ/122/1486ivo://CDS.VizieR/J/AJ/122/1486doi:10.26093/cds/vizier.51221486CDSPlatais I.Kozhurina-Platais V.Barnes S.Girard T.M.Demarque P.,van Altena W.F.Deliyannis C.P.Horch E.2023-04-06T16:50:44Z2002-02-10T13:40:37ZCDS support team

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

cds-question@unistra.fropen-star-clustersproper-motionsradial-velocityvisible-astronomybroad-band-photometryWe provide new evidence that NGC 2451A is undoubtedly a young open cluster, although sparsely populated. New cluster membership has been derived from relative proper motions of 5868 stars. In total, 136 stars down to V~15 5 have membership probability P{mu}>=2%. New CCD BV photometry indicates that about 70 stars are indeed main-sequence stars of NGC 2451A. This is also supported by our measurements of radial velocities. A total of 34 very likely cluster members yield a mean heliocentric radial velocity for NGC 2451A equal to +22.9km/s. The high quality of our BV photometry, a confirmation of cluster membership from proper motions and radial velocities, and a recently obtained metallicity estimate for several cluster stars allow us to perform a precise isochrone fit. The Yale isochrones, updated by the latest available input physics, have been fitted to the cluster's color-magnitude diagram, yielding a distance modulus V_0_-M_V_ in the range 6.35 to 6.38, which is in excellent agreement with the distance modulus (m-M)_0_=6.38 derived from the Hipparcos data recently by van Leeuwen and Robichon et al. (1998, Cat. <J/A+AS/130/157>). We have used the high-resolution spectra acquired using the Hydra multiobject spectrograph at the WIYN telescope (Kitt Peak, Arizona) in 1997 November and 1998 October.2001AJ....122.1486Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/122/1486CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-tohttp://www.astro.yale.edu/astrom : SPM Home PageI/252 : The USNO-A2.0 Catalogue (Monet+ 1998)I/277 : SPM catalog 2.0 (Platais+, 1998)J/AJ/124/601 : WIYN Open Cluster Study. VIII (Platais+, 2002)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/122/1486https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/122/1486http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/122/1486https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/122/1486https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/122/1486http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/122/1486GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/122/1486/table1 (Astrometry and photometry for probable cluster members in NGC 2451A)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/122/1486/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/122/1486/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/122/1486/table1?GETtext/xml+votable180.050000true114.81424583-39.465833330.005555555555555556Cone search capability for table J/AJ/122/1486/spm (Catalog of positions, relative proper motions and BV photographic photometry in the region of open cluster NGC 2451)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/122/1486/spm?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/122/1486/spm?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/122/1486/spm?GETtext/xml+votable180.050000true114.1923041-39.60355120.005555555555555556Cone search capability for table J/AJ/122/1486/ccd (Catalog of CCD BV photometry in the region of open cluster NGC 2451)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/122/1486/ccd?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/122/1486/ccd?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/122/1486/ccd?GETtext/xml+votable180.050000true114.079925-39.1017160.0055555555555555565/9838 9924 6/39341-39343 39346-39347 39356 39358 39684-39685 39687 397003.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/122/1486?format=asciiOpticaldefaultJ/AJ/122/1486/table1Astrometry and photometry for probable cluster members in NGC 2451ArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPKBRunning identification number, Cl* NGC 2451 PKB NNNNN in Simbadmeta.id;meta.mainintWill? The Williams (1967MNSSA..26...30W) number, NGC 2451 NNN in Simbadmeta.idintnullableRAJ2000Right Ascension (J2000, epoch J2000) (1)pos.eq.ra;meta.mainDEJ2000Declination (J2000, epoch J2000) (1)pos.eq.dec;meta.mainpmXRelative proper motion along X (2)mas/yrpos.pm;pos.cartesian.xfloatpmYRelative proper motion along Y (2)mas/yrpos.pm;pos.cartesian.yfloatVmagThe Johnson V band magnitudemagphot.mag;em.opt.Vfloatr_Vmag[aeu] Source of Vmag (3)meta.ref;pos.framecharB-VThe (B-V) colormagphot.color;em.opt.B;em.opt.Vfloato_VmagNumber of observations for Vmagmeta.numberintProbCluster membership probability%statintJ/AJ/122/1486/table3Radial velocitiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPKBRunning identification number, Cl* NGC 2451 PKB NNNNN in Simbadmeta.id;meta.mainintHJDHeliocentric Julian datedtime.epochdoubleHRVHeliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatn_HRV[a] indicates a broad cross-correlation peakmeta.notecharMembMembership status based on membership probability (2)meta.code.membercharJ/AJ/122/1486/spmCatalog of positions, relative proper motions and BV photographic photometry in the region of open cluster NGC 2451e_VmagEstimated standard error of V-magnitudemagstat.error;phot.mag;em.opt.VfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPKBRunning identification number, Cl* NGC 2451 PKB NNNNN in Simbadmeta.id;meta.mainintprimaryXposX position (1)mmpos.cartesian.x;instr.platefloatYposY position (1)mmpos.cartesian.y;instr.platefloatRAradRight ascension for the epoch 1991.25 and in the ICRS reference system (i.e. equinox 2000.0)degpos.eq.ra;meta.mainDEradDeclination for the epoch 1991.25 and equinox 2000.0degpos.eq.dec;meta.maine_RAradEstimated standard error in right ascension multiplied by cos(DE)masstat.errorinte_DEradEstimated standard error in declinationmasstat.errorintpmRARelative proper motion in right ascension multiplied by cos(DE)mas/yrpos.pm;pos.eq.rafloatpmDERelative proper motion in declinationmas/yrpos.pm;pos.eq.decfloato_BmagThe number of grating images per star detected on blue plates (grating image pairs are counted as one image)meta.numberinto_VmagThe number of grating images per star on visual platesmeta.numberinte_pmRAEstimated standard error in right ascension's proper motionmas/yrstat.error;pos.pm;pos.eq.rafloate_pmDEEstimated standard error in declination's proper motionmas/yrstat.error;pos.pm;pos.eq.decfloatBmag? Photographic B-magnitude (if missing then set to 0.00)magphot.mag;em.opt.Bfloatnullablee_BmagEstimated standard error of B-magnitudemagstat.error;phot.mag;em.opt.BfloatVmag? Photographic V-magnitude (if missing then set to 0.00)magphot.mag;em.opt.VfloatnullableVmagc? CCD V-magnitude (if missing then set to -1.000)magphot.mag;em.opt.VfloatnullableB-Vc? CCD B-V color (if missing then set to -1.000)magphot.color;em.opt.B;em.opt.Vfloatnullablee_VmagcIRAF generated error in CCD V-magnitudemagstat.error;phot.mag;em.opt.Vfloate_B-VcIRAF generated error in CCD B-V colormagstat.error;phot.color;em.opt.BfloatNframe[0/4]? Number of frames per star (G1)meta.numberintnullable_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into account (computed by VizieR, not part of the original data)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into account (computed by VizieR, not part of the original data)degpos.eq.decnullableindexedJ/AJ/122/1486/ccdCatalog of CCD BV photometry in the region of open cluster NGC 2451recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqObject identifier (1)meta.id;meta.mainlongRA1996Right ascension (mean epoch=1996.6, equinox J2000.0)degpos.eq.ra;meta.mainDE1996Declination (mean epoch=1996.6, equinox J2000.0)degpos.eq.dec;meta.mainVmagCCD V magnitudemagphot.mag;em.opt.VfloatB-VCCD B-V magnitudemagphot.color;em.opt.B;em.opt.Vfloate_VmagIRAF generated error in CCD V-magnitudemagstat.error;phot.mag;em.opt.Vfloate_B-VIRAF generated error in CCD B-V colormagstat.error;phot.color;em.opt.BfloatDRA"CCD-USNOA2.0" (<I/252>) coordinate difference in right ascension multiplied by cos(DE)arcsecstat.fit.residual;pos.eq.ra;arith.difffloatDDE"CCD-USNOA2.0" (<I/252>) coordinate difference in declinationarcsecstat.fit.residual;pos.eq.dec;arith.difffloatNframe[1/4] Number of frames per star (G1)meta.numberint_RA.icrsRight ascension (ICRS) at Epoch=J1996.6 (computed by VizieR, not part of the original data)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J1996.6 (computed by VizieR, not part of the original data)degpos.eq.decnullableindexed