J/PASP/130/L4101ivo://CDS.VizieR/J/PASP/130/L4101doi:10.26093/cds/vizier.61313101CDSGao X.-H.2025-09-09T14:14:54Z2019-04-08T16:04:17ZCDS support team

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

cds-question@unistra.fropen-star-clustersstellar-populationsMembership determination of open clusters in high-noise environments is still an open question. This paper aims to evaluate the effectiveness of the Gaussian mixture model (GMM) in segregating likely cluster members of open clusters in high-noise environments. We use the GMM method to segregate likely cluster members of four low Galactic latitude open clusters: NGC 2112, NGC 2477, NGC 7789, and Collinder 261, based on the high-precision astrometric data of the Gaia Data Release 2 (Gaia-DR2). The GMM method is used to calculate the membership probabilities of the stars in the field of each cluster; five astrometric parameters (positions, parallaxes, and proper motions) are taken into account. We quantitatively evaluate the goodness of the cluster-field segregation for each cluster, and find that the GMM method is effective for segregating likely cluster members of these clusters, even if these clusters suffer from heavy field star contamination. We estimate the distances and absolute proper motions of these clusters using reliable cluster members; our results suggest the existence of a significant zero-point offset in Gaia-DR2 parallaxes. NGC 2112, NGC 2477, NGC 7789, and Collinder 261 are found to have a mean distance of <D>=1104+/-4, 1437+/-2, 2067+/-4 and 2802+/-21pc, respectively. Mean proper motions of (<{mu}_{alpha}_cos{delta}>, <{mu}_{delta}_>)=(-2.714+/-0.012, 4.272+/-0.012), (-2.449+/-0.006, 0.876+/-0.006), (-0.919+/-0.004, -1.938+/-0.004), and (-6.348+/-0.006, -2.714+/-0.006)mas/yr are determined for NGC 2112, NGC 2477, NGC 7789, and Collinder 261, respectively.2018PASP..130l4101Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/PASP/130/L4101CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/PASP/130/L4101https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/PASP/130/L4101http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/PASP/130/L4101https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/PASP/130/L4101https://vizier.iucaa.in/viz-bin/votable?-source=J/PASP/130/L4101http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/PASP/130/L4101GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/PASP/130/L4101/table1 (Fundamental parameters of the four open clusters, taken from Dias et al. (2002A&A...389..871D, Cat. B/ocl))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/PASP/130/L4101/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/PASP/130/L4101/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/PASP/130/L4101/table1?GETtext/xml+votable180.050000true88.43750.410.005555555555555556Cone search capability for table J/PASP/130/L4101/table8 (Likely cluster members of the four open clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/PASP/130/L4101/table8?https://vizier.iucaa.in/viz-bin/conesearch/J/PASP/130/L4101/table8?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/PASP/130/L4101/table8?GETtext/xml+votable180.050000true88.4839972770.501127353790.0055555555555555566/14173 14175 22870-22871 39347 39350 39353 39356 41612-416131.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/PASP/130/L4101?format=asciidefaultJ/PASP/130/L4101/table1Fundamental parameters of the four open clusters, taken from Dias et al. (2002A&A...389..871D, Cat. B/ocl)DistCluster distance (1)pcpos.distance;pos.heliocentricintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster codemeta.codecharNameCluster namemeta.id;meta.maincharRAJ2000Cluster center right ascension (J2000) (1)degpos.eq.ra;meta.mainDEJ2000Cluster center declination (J2000) (1)degpos.eq.dec;meta.mainDiamAngular diameter (1)arcminphys.angSizeintE(B-V)Reddening (1)magphot.color.excessfloatpmRA*Proper motion along RA, pmRA*cosDE (1)mas/yrpos.pm;pos.eq.rafloate_pmRA*rms uncertainty on pmRA* (1)mas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion along DE (1)mas/yrpos.pm;pos.eq.decfloate_pmDErms uncertainty on pmDE (1)mas/yrstat.error;pos.pm;pos.eq.decfloatlogAgeAge (1)log(yr)time.agefloatNmembNumber of members in table8.datmeta.numberintSimbadSimbad column added by the CDSmeta.ref.urlcharJ/PASP/130/L4101/table8Likely cluster members of the four open clustersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster code (1)meta.codecharRA_ICRSGaia DR2 Right ascension (ICRS) at Epoch=2015.5degpos.eq.ra;meta.mainDE_ICRSGaia DR2 Right ascension (ICRS) at Epoch=2015.5degpos.eq.dec;meta.mainPlxGaia DR2 Parallaxmaspos.parallaxfloate_Plxrms uncertainty on Plxmasstat.error;pos.parallaxfloatpmRA*Gaia DR2 proper motion along RA (pmRA*cosDE)mas/yrpos.pm;pos.eq.rafloate_pmRA*rms uncertainty on pmRA*mas/yrstat.error;pos.pm;pos.eq.rafloatpmDEGaia DR2 proper motion along DEmas/yrpos.pm;pos.eq.decfloate_pmDErms uncertainty on pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatGmagGaia DR2 magnitudemagphot.mag;em.optfloate_Gmagrms uncertainty on Gmagmagstat.error;phot.magfloatG-RPGaia DR2 G-RP colour indexmagphot.color;em.opt;em.optfloatPmembMembership probability calculated in this workstat.probability;meta.modelledfloat_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decnullableindexedSimbadNameSimbad column added by the CDSmeta.idchar