J/ApJ/869/9ivo://CDS.VizieR/J/ApJ/869/9doi:10.26093/cds/vizier.18690009CDSGao X.2020-02-04T10:08:48Z2019-12-27T14:29:36ZCDS support team

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

cds-question@unistra.fropen-star-clustersproper-motionstwo-color-diagramsvisible-astronomytrigonometric-parallaxnarrow-band-photometryIn this paper, we use a machine-learning method, random forest (RF), to identify reliable members of the old (4Gyr) open cluster M67 based on the high-precision astrometry and photometry taken from the second Gaia data release (Gaia-DR2). The RF method is used to calculate membership probabilities of 71117 stars within 2.5{deg} of the cluster center in an 11-dimensional parameter space, the photometric data are also taken into account. Based on the RF membership probabilities, we obtain 1502 likely cluster members (>=0.6), 1361 of which are high-probability cluster members (>=0.8). Based on high-probability memberships with high-precision astrometric data, the mean parallax (distance) and proper-motion of the cluster are determined to be 1.1327+/-0.0018mas (883+/-1pc) and (<{mu}_{alpha}_cos{delta}>,<{mu}_{delta}_>)=(-10.9378+/-0.0078,-2.9465 +/-0.0074)mas/yr, respectively. We find the cluster to have a mean radial velocity of +34.06+/-0.09km/s, using 74 high-probability cluster members with precise radial-velocity measures. We investigate the spatial structure of the cluster, the core and limiting radius are determined to be 4.80'+/-0.11' (~1.23+/-0.03pc) and 61.98'+/-1.50' (~15.92+/-0.39pc), respectively. Our results reveal that an escaped member with high membership probability (~0.91) is located at a distance of 77' (~20pc) from the cluster center. Furthermore, our results reveal that at least 26.4% of the main-sequence stars in M67 are binary stars. We confirm that significant mass segregation has taken place within M67.2018ApJ...869....9Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/869/9CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/337 : Gaia DR1 (Gaia Collaboration, 2016)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/AJ/112/628 : BATC Color Survey of M67 (Fan+ 1996)J/A+A/376/441 : Absolute proper motions of 112 open clusters (Dias+, 2001)J/A+A/381/464 : Proper motions and membership in NGC 2548 (Wu+, 2002)J/A+A/388/168 : Absolute proper motions of 93 open clusters (Dias+, 2002)J/MNRAS/347/101 : Precision colour-magnitude diagram of M67 (Sandquist, 2004)J/A+A/470/585 : NGC 2682 uvby-Hbeta photometry (Balaguer-Nunez+, 2007)J/A+A/484/609 : BVI photometry and proper motions in M67 (Yadav+, 2008)J/A+A/511/A56 : Abundances of five open clusters (Pancino+, 2010)J/MNRAS/414/2602 : Automated classification of HIP variables (Dubath+, 2011)J/MNRAS/424/2832 : Pulsars in {gamma}-ray sources (Lee+, 2012)J/A+A/545/A139 : Radial Velocities of stars observed in M67 (Pasquini+, 2012)J/A+A/558/A53 : Milky Way survey of star clusters. II. (Kharchenko+,2013)J/A+A/563/A45 : Pleiades cluster membership probabilities (Sarro+, 2014)J/A+A/564/A79 : Proper motions of open clusters from UCAC4 (Dias+, 2014)J/A+A/584/A44 : Photometric classification QSO from RCS-2 (Carrasco+, 2015)J/AJ/150/97 : Rad-velocities M67. I. 1278 candidate members (Geller+,2015)J/ApJ/809/161 : X-ray obs. and membership probabilities M37 (Nunez+, 2015)J/ApJ/813/28 : Autoclassification of variable 3XMM sources (Farrell+, 2015)J/other/PASA/32.36 : lambda Boo star membership evaluations (Murphy+, 2015)J/MNRAS/456/3757 : Open-cluster density profiles (Seleznev, 2016)J/MNRAS/463/696 : M67 solar twins chemical compositions (Liu+, 2016)J/A+A/601/A19 : Gaia DR1 open cluster members (Gaia Collaboration+, 2017)J/A+A/603/A85 : M67 stars radial velocities (Brucalassi+, 2017)J/AJ/156/121 : Catalog 518 likely open cluster NGC6405 members (Gao, 2018)J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Collab, 2018)J/A+A/617/A15 : Membership probabilities Pleiades objects (Olivares+, 2018)J/AJ/158/16 : Identif of RR Lyrae stars from the DES (Stringer+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/869/9https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/869/9http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/869/9https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/869/9https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/869/9http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/869/9GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/869/9/table3 (A catalog of fundamental information for 1502 likely cluster members with P_RF_>=0.6)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/869/9/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/869/9/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/869/9/table3?GETtext/xml+votable180.050000true133.0891195857211.844945045880.005555555555555556Cone search capability for table J/ApJ/869/9/table4 (*Fundamental parameters of the 45 likely escapers)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/869/9/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/869/9/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/869/9/table4?GETtext/xml+votable180.050000true132.0961858953612.872409014810.0055555555555555565/1063 1069 1074 6/4246 4247 4251 4273 4288 4290 4291 4294 4300 4302 4320 4321 4322 43261.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/869/9?format=asciiOpticaldefaultJ/ApJ/869/9/table3A catalog of fundamental information for 1502 likely cluster members with P_RF_>=0.6recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEDisplay the parameters for this likely escaper (link to Table 4)meta.ref.urlcharGaiaDR2Gaia-DR2 identifier of the likely cluster members (<Gaia DR2 NNNNNNNNNNNNNNNNNNN> in Simbad)meta.id;meta.mainprimaryRAJ2000[130.39/135.3] Gaia DR2 right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[9.3/14.3] Gaia DR2 declination (J2000)degpos.eq.dec;meta.mainPRF[0.6/1] RF cluster membership probabilitystat.probabilityfloatSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJ/869/9/table4*Fundamental parameters of the 45 likely escaperse_Plx[0.02/0.38] Error on Plxmasstat.error;pos.parallaxfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR2Gaia-DR2 identifier of the likely cluster members (<Gaia DR2 NNNNNNNNNNNNNNNNN> in Simbad)meta.id;meta.datasetRAJ2000[131.1/135.3] Gaia DR2 right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[10.29/13.4] Gaia DR2 declination (J2000)degpos.eq.dec;meta.mainPlx[0.98/1.39] Gaia DR2 parallax ({pi})maspos.parallaxfloatpmRA[-11.7/-10.5] Gaia DR2 proper motion in RA ({mu}_{alpha}_cos{delta})mas/yrpos.pm;pos.eq.rafloate_pmRA[0/0.6] Error on pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDE[-3.5/-2.4] Gaia DR2 proper motion in DEC ({mu}_{delta}_)mas/yrpos.pm;pos.eq.decfloate_pmDE[0/0.5] Error on pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatGmag[12.5/19.2] Gaia DR2 apparent G-band magnitudemagphot.mag;em.opt.VfloatG-RP[0.35/1.11] Gaia DR2 G-RP color indexmagphot.color;em.opt;em.optfloatPRF[0.8/1] RF cluster membership probabilitystat.probabilityfloatRV[35.13]? Gaia DR2 radial velocitykm/sphys.veloc;pos.heliocentricfloatnullablee_RV[0.73]? Error on RVkm/sstat.errorfloatnullable