J/AJ/145/37ivo://CDS.VizieR/J/AJ/145/37doi:10.26093/cds/vizier.51450037CDSSung H.Sana H.Bessell M.S.2014-06-16T13:12:48Z2014-06-03T15:07:10ZCDS support team

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

cds-question@unistra.fropen-star-clusterspre-main-sequence-starsvisible-astronomyh-alpha-photometryinfrared-photometrybroad-band-photometryccd-photometryWe have performed new wide-field photometry of the young open cluster NGC6231 to study the shape of the initial mass function (IMF) and mass segregation. We also investigated the reddening law toward NGC6231 from optical to mid-infrared color excess ratios, and found that the total-to-selective extinction ratio is R_V_=3.2, which is very close to the normal value. But many early-type stars in the cluster center show large color excess ratios. We derived the surface density profiles of four member groups, and found that they reach the surface density of field stars at about 10', regardless of stellar mass. The IMF of NGC6231 is derived for the mass range 0.8-45M_{sun}_. The slope of the IMF of NGC6231 ({Gamma}=-1.1+/-0.1) is slightly shallower than the canonical value, but the difference is marginal. In addition, the mass function varies systematically, and is a strong function of radius-it is very shallow at the center, and very steep at the outer ring suggesting the cluster is mass segregated. We confirm the mass segregation for the massive stars (m>~8 M_{sun}_) by a minimum spanning tree analysis. Using a Monte Carlo method, we estimate the total mass of NGC6231 to be about 2.6(+/-0.6)*10^3^M_{sun}_. We constrain the age of NGC 6231 by comparison with evolutionary isochrones. The age of the low-mass stars ranges from 1 to 7Myr with a slight peak at 3Myr. However, the age of the high-mass stars depends on the adopted models and is 3.5+/-0.5Myr from the non-rotating or moderately rotating models of Brott et al. (2011, cat. J/A+A/530/A115) as well as the non-rotating models of Ekstrom et al. (2012, cat. J/A+A/537/A146). But the age is 4.0-7.0Myr if the rotating models of Ekstrom et al. (2012, cat. J/A+A/537/A146) are adopted. This latter age is in excellent agreement with the timescale of ejection of the high-mass runaway star HD153919 from NGC6231, albeit the younger age cannot be entirely excluded.2013AJ....145...37Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/145/37CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)J/A+A/530/A115 : Rotating massive MS stars evolutionary models (Brott+, 2011)J/AJ/135/441 : VRIH{alpha} photometry in NGC 2264 (Sung+, 2008)J/MNRAS/386/447 : RV catalogue of O-type stars in NGC 6231 (Sana+, 2008)J/A+A/454/1047 : XMM view of NGC 6231 open cluster (Sana+, 2006)J/AJ/128/1684 : NGC 2264: VRIH{alpha} photometry (Sung+, 2004)J/AJ/127/1014 : CCD UBVRIHa photometry in NGC 3603 (Sung+, 2004)J/AJ/120/333 : UBVRI and H{alpha} in NGC 6530 (Sung+, 2000)J/MNRAS/310/982 : UBVI CCD Photometry of M11 - II. (Sung+ 1999)J/A+AS/137/233 : UBVI imaging photometry of NGC 6231 (Baume+, 1999)J/AJ/115/734 : NGC 6231 UBVRI and H{alpha} photometry (Sung+ 1998)J/ApJS/116/263 : VI photometry of open clusters (Piatti+ 1998)J/AJ/114/2644 : UBVRIHa photometry of NGC 2264 (Sung+, 1997)J/A+A/325/167 : Geneva photometry in NGC 6231 (Raboud+ 1997)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/145/37https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/145/37http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/145/37https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/145/37https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/145/37http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/145/37GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/145/37/table2 (UBVIH{alpha} photometry of NGC 6231)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/145/37/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/145/37/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/145/37/table2?GETtext/xml+votable180.050000true253.5826667-41.83608330.0055555555555555566/42383 42394 42416https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/145/37?format=asciiOpticalInfrareddefaultJ/AJ/145/37/table2UBVIH{alpha} photometry of NGC 6231ONameOther namemeta.idcharStar[-15/30123] Running star number (1)meta.id;meta.mainintprimaryf_Star[DV] Duplicity or Variability flag (4)meta.codecharn_Star[*] Star missed in the new photometry (2)meta.notecharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainindexedDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainindexedo_VmagNumber of Vmag observationsmeta.numberintVmagThe V band magnitudemagphot.mag;em.opt.Vfloate_VmagUncertainty in Vmagmagstat.error;phot.mag;em.opt.Vfloato_V-INumber of V-I observationsmeta.numberintV-I? The (V-I) color indexmagphot.color;em.opt.V;em.opt.Ifloatnullablee_V-I? Uncertainty in V-Imagstat.error;phot.color;em.opt.Vfloatnullableo_B-VNumber of B-V observationsmeta.numberintB-V? The (B-V) color indexmagphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V? Uncertainty in B-Vmagstat.error;phot.color;em.opt.Bfloatnullableo_U-BNumber of U-B observationsmeta.numberintU-B? The (U-B) color indexmagphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B? Uncertainty in U-Bmagstat.error;phot.color;em.opt.Ufloatnullableo_HaNumber of Ha observationsmeta.numberintHa? H{alpha} index (R-H{alpha})magspect.index;em.line.Halphafloatnullablee_Ha? Uncertainty in Hamagstat.errorfloatnullable2MASSThe 2MASS identifier (from cat. II/246)meta.idcharMm[VXHh+-] Membership code (3)meta.code.membercharSBL98[-8/9999]? Identifier in Sung et al. (1998, cat. J/AJ/115/734)meta.idintnullableSpTn? Numerical spectral type (5)src.spTypefloatnullableLum? Numerical luminosity class (6)src.class.luminosityfloatnullableOName2Other namemeta.idcharOName3Other namemeta.idcharSpTMK spectral type and luminosity classsrc.spTypecharComComment (variable type, or origin of H{alpha} emission star)meta.notechar