J/AJ/156/121ivo://CDS.VizieR/J/AJ/156/121doi:10.26093/cds/vizier.51560121CDSGao X.2020-01-31T11:41:06Z2019-11-19T10:25:35ZCDS support team

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

cds-question@unistra.fropen-star-clustersastronomical-modelsstellar-populationsThis paper presents a combined method of Gaussian mixture model and random forest to compute membership probabilities of stars by using large, high-dimensional data sets. A significant advantage of this method is that it allows us to easily identify likely cluster members in large data sets starting from small training samples. As a benchmark, we select 40318 stars in the field of the open cluster NGC 6405 from the Gaia Data Release 2 (Gaia-DR2, Cat. I/345) by means of all five astrometric (positions, proper motions, and parallax) and photometric parameters. We use this combined method to determine likely cluster members in an eleven-dimensional parameter space. A total number of 518 high-probability (>=0.6) memberships are obtained, and the mean parallax and proper motion of the cluster are determined to be 2.171+/-0.005 mas (461+/-1 pc) and (<{mu}_{alpha}_cos{delta}>, <{mu}_{delta}_>)=(-1.357+/-0.023, -5.823+/-0.020) mas/yr, respectively. In addition, we quantitatively evaluate the relative importance of the parameters for membership determination and find that colors and magnitudes cannot be ignored in membership determination when using the RF method. Our results show that this combined method exhibits good performance in handling arbitrary high-dimensional and large data sets, such as Gaia-DR2, and it can also be used to investigate other open clusters.2018AJ....156..121Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/156/121CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/446/949 : Open clusters proper motions based on UCAC2 (Dias+, 2006)J/A+A/454/171 : CCD {Delta}a-photometry of 8 open clusters (Paunzen+, 2006)J/PAZh/38/571 : Astrophysical parameters for 593 open clustersJ/A+A/585/A101 : Milky Way global survey of star clusters. V.J/AJ/151/49 : M6 open cluster: star members properties (Kilicoglu+, 2016)J/MNRAS/470/3937 : 1876 open clusters multimembership catalog (Sampedro+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/156/121https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/156/121http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/156/121https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/156/121https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/156/121http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/156/121GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/156/121/table1 (A catalog of fundamental information for 518 likely cluster members with P_RF_>=0.6)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/156/121/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/156/121/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/156/121/table1?GETtext/xml+votable180.050000true265.05610754016-32.219418147770.0055555555555555566/28806 28807 28812 28813https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/156/121?format=asciidefaultJ/AJ/156/121/table1A catalog of fundamental information for 518 likely cluster members with P_RF_>=0.6recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceGaia DR2 identifiermeta.id;meta.mainRA_ICRSGaia DR2 Right Ascension (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRSGaia DR2 Declination (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainPRF[0.603/1] Random Forest (RF) membership probabilitystat.fit.goodnessfloatSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2015.5 (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexed