J/A+A/621/L3ivo://CDS.VizieR/J/A+A/621/L3doi:10.26093/cds/vizier.36219003CDSMeingast S.Alves J.2020-04-02T05:00:23Z2019-01-11T12:07:24ZCDS support team

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

cds-question@unistra.fropen-star-clustersastrometryWe report the discovery of two well-defined tidal tails emerging from the Hyades star cluster. The tails were detected in Gaia DR2 data by selecting cluster members in the 3D galactocentric cylindrical velocity space. The robustness of our member selection is reinforced by the fact that the sources depict an almost noiseless, coeval stellar main sequence in the observational Hertzsprung-Russel diagram. The spatial arrangement of the selected members represents a highly flattened shape with respect to the direction of movement along the clusters' orbit in the Galaxy. The size of the entire structure, within the limits of the observations, measures about 200pc in its largest extent, while being only about 25pc thick. This translates into an on-sky extent of well beyond 100deg. Intriguingly, a top-down view on the spatial distribution reveals a distinct S-shape, reminiscent of tidal tails that have been observed for globular clusters and also of tails that were modeled for star clusters bound to the Galactic disk. Even more remarkable, the spatial arrangement as well as the velocity dispersion of our source selection is in excellent agreement with previously published theoretical predictions for the tidal tails of the Hyades. An investigation into observed signatures of equipartition of kinetic energy, that is, mass segregation, remains unsuccessful, most likely because of the sensitivity limit for radial velocity measurements with Gaia.2019A&A...621L...3Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/621/L3CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/243/386 : Hyades members distances (Schwan 1991)J/A+A/331/81 : Hyades membership (Perryman+ 1998)J/A+A/367/111 : A Hipparcos study of the Hyades cluster (de Bruijne+, 2001)J/A+A/621/L2 : Hyades tidal tails revealed by Gaia DR2 (Roeser+, 2019)J/A+A/622/L13 : Stellar stream in Gaia DR2 discovery (Meingast+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/621/L3https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/621/L3http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/621/L3https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/621/L3https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/621/L3http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/621/L3GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/621/L3/hyades (Hyades selection)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/621/L3/hyades?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/621/L3/hyades?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/621/L3/hyades?GETtext/xml+votable180.050000true352.9533875639.211378220.0055555555555555565/5881 6/60 78 211 272 303 309 318 320 322-323 326 333-334 336-337 339-342 348-349 357 360 365 373 378 381 383 462 472 478 483 507 701 712 770 835 890 917 997 1024-1026 1032 1035-1036 1038 1042 1044 1057-1058 1060 1075 1211 1577 1720 2052 2086 2178 2328 2525 2535 2609 2828 2830 2838 3032 3335 13503 13643 13650 13758 13774 13805 14036 14061 14091 14114 14122 14126 14142 14149 14233 14259 14294 18544 19361 19446 20157 20737 20842 20846 20883 20932 21082 21307-21308 21354 21372 21485 21493 21496 22176 22185 22566 22598 22811 22882 22908 23017 23026 23035 23286 23313 23321 23329 23344 23368 23387 23408 23418 23450 23453-23454 23478-23479 23487 23489-23490 23496-23497 23501-23505 23511 23514 23518 23522-23523 23529 23533-23535 23537-23539 23542 23544-23545 23547-23548 23651 23660 23704 23714 23726-23727 24068 24070 24075 24099 24104 24109-24110 24126 24130 24175 24192 24194 24200-24201 24203 24206-24209 24211-24212 24232 24234 24239 24248 24251-24252 24266 36922 39670 39730 39733 39834 40986 455681.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/621/L3?format=asciidefaultJ/A+A/621/L3/hyadesHyades selectionrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDR2NameGaia DR2 Unique source designation, Gaia DR2 NNNNNNNNNNNNNNNNNNN (designation)meta.idcharSourceGaia DR2 Unique source identifier (source_id)meta.id;meta.mainRA_ICRSGaia DR2 Right ascension (ICRS) at Ep=2015.5 (ra)degpos.eq.ra;meta.mainDE_ICRSGaia DR2 Declination (ICRS) at Ep=2015.5 (dec)degpos.eq.dec;meta.mainPlxGaia DR2 Parallax (parallax)maspos.parallaxdoublee_PlxGaia DR2 Standard error of parallax (parallax_error)masstat.error;pos.parallaxdoublepmRAGaia DR2 Proper motion in ra direction (pmra)mas/yrpos.pm;pos.eq.radoublee_pmRAGaia DR2 Standard error of proper motion in ra direction (pmra_error)mas/yrstat.error;pos.pm;pos.eq.radoublepmDEGaia DR2 Proper motion in dec direction (pmdec)mas/yrpos.pm;pos.eq.decdoublee_pmDEGaia DR2 Standard error of proper motion in dec direction (pmdec_error)mas/yrstat.error;pos.pm;pos.eq.decdoubleamaxGaia DR2 The longest semi-major axis of the 5-d error ellipsoid (astrometric_sigma5d_max)maspos.errorEllipse;stat.maxdoubleGmagGaia DR2 G-band mean magnitude (phot_g_mean_mag)magphot.mag;em.optfloatBPmag? Gaia DR2 Integrated BP mean magnitude (phot_bp_mean_mag)magphot.mag;em.opt.BfloatnullableRPmag? Gaia DR2 Integrated RP mean magnitude (phot_rp_mean_mag)magphot.mag;em.opt.RfloatnullableRVGaia DR2 Radial velocity (radial_velocity)km/sphys.veloc;pos.heliocentricdoublee_RVGaia DR2 Radial velocity error (radial_velocity_error)km/sstat.errordoubleXGalactic Cartesian X (X)pcpos.cartesian.x;pos.galacticfloatYGalactic Cartesian Y (Y)pcpos.cartesian.y;pos.galacticfloatZGalactic Cartesian Z (Z)pcsrc.redshift;pos.cartesian;pos.galacticfloatgcRGalactocentric Cylindrical R (gc_R)pcpos.distance;pos.galactocentricdoublegcPHIGalactocentric Cylindrical PHI (gc_PHI)pcpos.distance;pos.galactocentricdoublegcZGalactocentric Cylindrical Z (gc_Z)pcpos.distance;pos.galactocentricdoublegcvRGalactocentric Cylindrical vR (gc_vR)km/sphys.veloc;pos.galactocentricfloatgcvPHIGalactocentric Cylindrical vPHI (gc_vPHI)km/sphys.veloc;pos.galactocentricfloatgcvZGalactocentric Cylindrical vZ (gc_vZ)km/sphys.veloc;pos.galactocentricfloatSimbadSimbad 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