J/A+A/645/A116ivo://CDS.VizieR/J/A+A/645/A116doi:10.26093/cds/vizier.36450116CDSKundu R.Navarrete C.Fernandez-Trincado J.G.Minniti D.Singh H.P.,Sbordone L.Piatti A.Reyle C.2021-09-10T09:21:31Z2021-01-22T09:54:22ZCDS support team

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

cds-question@unistra.frglobular-star-clustersproper-motionsphotometryvisible-astronomyExtratidal stars are stellar bodies that end up outside the tidal radius of a cluster as a result of internal processes or external forces acting upon it. The presence and spatial distribution of these stars can give us insights into the past evolution of a cluster inside our Galaxy. Previous works suggest that globular clusters, when explored in detail, show evidence of extratidal stars. We aim to search for possible extratidal stars in the Galactic globular clusters NGC 6397, NGC 2808, and NGC 6266 using the photometry and proper motion measurements from Gaia DR2 database. The extratidal stars for the clusters were selected on the basis of: their distance from the cluster center, similarity in their proper motions to the cluster population, and their position on the color-magnitude diagram of the clusters. Each cluster was explored in an annulus disk from the tidal radius up to five times the tidal radii. The significance level of the number of selected extratidal stars was determined on the basis of the distribution of Milky Way stars according to the Besancon Galaxy model and Gaia data. To understand the observed extratidal features, the orbits of the clusters were also determined using GravPot16. Finally, 120, 126, and 107 extratidal candidate stars were found lying outside the tidal radius of the globular clusters NGC 6397, NGC 2808, and NGC 6266, respectively. 70%, 25.4%, and 72.9% of the extratidal stars found are located outside the Jacobi radius of NGC 6397, NGC 2808, and NGC 6266, respectively. The spatial distribution of the extratidal stars belonging to NGC 6397 appears S-like, extending along the curved leading and trailing arms. NGC 2808 has an overdensity of stars in the trailing part of the cluster and NGC 6266 seems to have overdensities of extratidal stars in its eastern and northern sides. Proper motions and color-magnitude diagrams can be used to identify extratidal candidate stars around GCs. Nonetheless, depending on how different the kinematics and stellar populations of a cluster are compared to the Milky Way field, the fraction of contamination can be larger. All three clusters are found to have extratidal stars outside their tidal radii. For NGC 6397 and NGC 2808, these stars may be the result of a combined effect of the disc shocks and tidal disruptions. For NGC 6266, the distribution of extratidal stars is symmetrical around it, most likely indicating that the cluster has an extended stellar envelope.2021A&A...645A.116Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/645/A116CatalogResearchIsServedByTAP 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/A+A/645/A116https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/645/A116http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/645/A116https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/645/A116https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/645/A116http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/645/A116GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/645/A116/ngc2808 (Extra-tidal candidates around NGC 2808)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/645/A116/ngc2808?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/645/A116/ngc2808?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/645/A116/ngc2808?GETtext/xml+votable180.050000true137.66289977536-64.527295165060.005555555555555556Cone search capability for table J/A+A/645/A116/ngc6266 (Extra-tidal candidates around NGC 6266)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/645/A116/ngc6266?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/645/A116/ngc6266?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/645/A116/ngc6266?GETtext/xml+votable180.050000true254.44718688656-30.132942376010.005555555555555556Cone search capability for table J/A+A/645/A116/ngc6397 (Extra-tidal candidates around NGC 6397)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/645/A116/ngc6397?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/645/A116/ngc6397?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/645/A116/ngc6397?GETtext/xml+votable180.050000true259.45477389501-52.513290351290.0055555555555555565/10515 10517-10518 6/37290-37292 37294-37295 37632-37633 37635-37638 42054-42055 42057 42059 42065-42067 42076-42078 42080-42081 42084-42085 42087 42097-42098 42102 42241-42244 42246 42248 42251-42252 42834-42835 42838 42840-42841 42843-42844 47274 47616 47618 476241.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/645/A116?format=asciiOpticaldefaultJ/A+A/645/A116/ngc2808Extra-tidal candidates around NGC 2808recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceGaia DR2 IDmeta.id;meta.mainRA_ICRSRight ascension (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainpmRA*Proper motion in RA*cos(DE)mas/yrpos.pm;pos.eq.rafloate_pmRA*Error in proper motion in RA*cos(DE)mas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in DEmas/yrpos.pm;pos.eq.decfloate_pmDEError in proper motion in DEmas/yrstat.error;pos.pm;pos.eq.decfloatGmagGaia DR2 G-band magnitudemagphot.mag;em.optdoubleBPmagGaia DR2 BP-band magnitudemagphot.mag;em.opt.BdoubleRPmagGaia DR2 RP-band magnitudemagphot.mag;em.opt.Rdouble_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/645/A116/ngc6266Extra-tidal candidates around NGC 6266recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceGaia DR2 IDmeta.id;meta.mainRA_ICRSRight ascension (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainpmRA*Proper motion in RA*cos(DE)mas/yrpos.pm;pos.eq.rafloate_pmRA*Error in proper motion in RA*cos(DE)mas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in DEmas/yrpos.pm;pos.eq.decfloate_pmDEError in proper motion in DEmas/yrstat.error;pos.pm;pos.eq.decfloatGmagGaia DR2 G-band magnitudemagphot.mag;em.optdoubleBPmagGaia DR2 BP-band magnitudemagphot.mag;em.opt.BdoubleRPmagGaia DR2 RP-band magnitudemagphot.mag;em.opt.Rdouble_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/645/A116/ngc6397Extra-tidal candidates around NGC 6397recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceGaia DR2 IDmeta.id;meta.mainRA_ICRSRight ascension (ICRS) at Ep=2015.5degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2015.5degpos.eq.dec;meta.mainpmRA*Proper motion in RA*cos(DE)mas/yrpos.pm;pos.eq.rafloate_pmRA*Error in proper motion in RA*cos(DE)mas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in DEmas/yrpos.pm;pos.eq.decfloate_pmDEError in proper motion in DEmas/yrstat.error;pos.pm;pos.eq.decfloatGmagGaia DR2 G-band magnitudemagphot.mag;em.optdoubleBPmagGaia DR2 BP-band magnitudemagphot.mag;em.opt.BdoubleRPmagGaia DR2 RP-band magnitudemagphot.mag;em.opt.Rdouble_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