J/A+A/627/A35ivo://CDS.VizieR/J/A+A/627/A35doi:10.26093/cds/vizier.36270035CDSCastro-Ginard A.Jordi C.Luri X.Cantat-Gaudin T.Balaguer-Nunez L.2021-02-05T08:26:16Z2019-07-01T12:08:18ZCDS support team

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

cds-question@unistra.frmilky-way-galaxygalactic-centeropen-star-clustersThe Gaia Data Release 2 (DR2) provided an unprecedented volume of precise astrometric and excellent photometric data. In terms of data mining the Gaia catalogue, machine learning methods have shown to be a powerful tool, for instance in the search for unknown stellar structures. Particularly, supervised and unsupervised learning methods combined together significantly improves the detection rate of open clusters. We systematically scan Gaia DR2 in a region covering the Galactic anticentre and the Perseus arm (120{deg}<=l<=205{deg} and -10{deg}<=b<=10{deg}), with the goal of finding any open clusters that may exist in this region, and fine tuning a previously proposed methodology and successfully applied to TGAS data, adapting it to different density regions. Our methodology uses an unsupervised, density-based, clustering algorithm, DBSCAN, that identifies overdensities in the five-dimensional astrometric parameter space (l, b, {varpi}, pmRA*, pmDE) that may correspond to physical clusters. The overdensities are separated into physical clusters (open clusters) or random statistical clusters using an artificial neural network to recognise the isochrone pattern that open clusters show in a colour magnitude diagram. The method is able to recover more than 75% of the open clusters confirmed in the search area. Moreover, we detected 53 open clusters unknown previous to Gaia DR2, which represents an increase of more than 22% with respect to the already catalogued clusters in this region. We find that the census of nearby open clusters is not complete. Different machine learning methodologies for a blind search of open clusters are complementary to each other; no single method is able to detect 100% of the existing groups. Our methodology has shown to be a reliable tool for the automatic detection of open clusters, designed to be applied to the full Gaia DR2 catalogue.2019A&A...627A..35Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/627/A35CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/618/A59 : New nearby open clusters confirmed by Gaia DR2https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/627/A35https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/627/A35http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/627/A35https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/627/A35https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/627/A35http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/627/A35GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/627/A35/centres (Mean parameters for the reported UBC clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/627/A35/centres?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/627/A35/centres?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/627/A35/centres?GETtext/xml+votable180.050000true7.394417178359660.49116515210560.005555555555555556Cone search capability for table J/A+A/627/A35/members (Members for the reported UBC clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/627/A35/members?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/627/A35/members?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/627/A35/members?GETtext/xml+votable180.050000true7.400521365964860.514565828070.0055555555555555566/1270-1271 1276-1277 1282-1283 1296-1297 1299 1310-1311 1318 1321 1323-1324 1326 1329 1332 1448 1509 1511 1627 1648-1649 1655 1661 1734-1735 1740-1741 1746-1747 1752-1753 1788-1789 1807 1826 1829 1832 1931 2937 2939 3009 3028 3045 3139 3145 3201 3203 3242 3258-3259 3322-3323 3331 3342 3364 3595-3598 3600-3601 3619 3626-3627 3714 3738-3739 3760 3783 3789 3794 23621 23623 23628-23629 23631 23650 23656 23665 23784 23801 23803 23851 23996 24130 24372 24374 24460-24461 24513 24516 24539 245611.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/627/A35?format=asciidefaultJ/A+A/627/A35/centresMean parameters for the reported UBC clustersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster name (UBC33-UBC99)meta.id.parentcharRA_ICRSRight Ascension mean (ICRS) at epoch 2015.5degpos.eq.ra;meta.maine_RA_ICRSRight Ascension standard deviationdegstat.error;pos.eq.radoubleDE_ICRSDeclination mean (ICRS) at epoch 2015.5degpos.eq.dec;meta.maine_DE_ICRSDeclination standard deviationdegstat.error;pos.eq.decdoubleGLONGalactic longitude meandegpos.galactic.lone_GLONGalactic longitude standard deviationdegstat.errordoubleGLATGalactic latitude meandegpos.galactic.latdoublee_GLATGalactic latitude standard deviationdegstat.errordoublePlxParallax meanmaspos.parallax;stat.meandoublee_PlxParallax standard deviationmasstat.error;pos.parallaxdoublepmRA*Proper motion in right ascension mean (pmRA*cosDE)mas/yrpos.pm;pos.eq.radoublee_pmRA*Proper motion in right ascension standard deviationmas/yrstat.error;pos.pm;pos.eq.radoublepmDEProper motion in declination meanmas/yrpos.pm;pos.eq.decdoublee_pmDEProper motion in declination standard deviationmas/yrstat.error;pos.pm;pos.eq.decdoubleSimbadSimbad column added by the CDSmeta.ref.urlchar_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.decnullableindexedJ/A+A/627/A35/membersMembers for the reported UBC clustersSourceGaia source_idmeta.id;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRA_ICRSRight Ascension (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latdoublePlxAbsolute stellar parallaxmaspos.parallaxdoublepmRA*Proper motion in right ascension (pmRA*cosDE)mas/yrpos.pm;pos.eq.radoublepmDEProper motion in declinationmas/yrpos.pm;pos.eq.decdoubleRV? Radial velocitykm/sphys.veloc;pos.heliocentricdoublenullableGmagGaia G mean magnitudemagphot.mag;em.optdoubleBP-RP? Gaia BP-RP colour indexmagphot.color;em.opt.B;em.opt.RdoublenullableClusterCluster namemeta.id.parentcharSimbadSimbad column added by the CDSmeta.ref.urlchar_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.decnullableindexed