J/ApJ/751/132ivo://CDS.VizieR/J/ApJ/751/132doi:10.26093/cds/vizier.17510132CDSClarkson W.I.Ghez A.M.Morris M.R.Lu J.R.Stolte A.McCrady N.,Do T.Yelda S.2014-03-01T16:24:47Z2014-02-17T09:12:01ZCDS support team

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

cds-question@unistra.frproper-motionsinfrared-photometryopen-star-clustersWe report the first detection of the intrinsic velocity dispersion of the Arches cluster - a young (~2Myr), massive (10^4^M_{sun}_) starburst cluster located only 26pc in projection from the Galactic center. This was accomplished using proper motion measurements within the central 10"x10" of the cluster, obtained with the laser guide star adaptive optics system at Keck Observatory over a three-year time baseline (2006-2009). This uniform data set results in proper motion measurements that are improved by a factor ~5 over previous measurements from heterogeneous instruments. By careful, simultaneous accounting of the cluster and field contaminant distributions as well as the possible sources of measurement uncertainties, we estimate the internal velocity dispersion to be 0.15+/-0.01mas/yr, which corresponds to 5.4+/-0.4km/s at a distance of 8.4kpc. Collateral benefits of our data and analysis include: (1) cluster membership probabilities, which may be used to extract a clean-cluster sample for future photometric work; (2) a refined estimate of the bulk motion of the Arches cluster with respect to the field, which we find to be 172+/-15km/s, which is slightly slower than suggested by previous measurements using one epoch each with the Very Large Telescope and the Keck telescope; and (3) a velocity dispersion estimate for the field itself, which is likely dominated by the inner Galactic bulge and the nuclear disk.2012ApJ...751..132Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/751/132CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/556/A26 : Arches cluster: IR phot., extinction and masses (Habibi+, 2013)J/ApJ/718/810 : Astrometry and Photometry in the Arches cluster (Stolte+, 2010)J/A+A/501/563 : HKs photometry in the Arches cluster (Espinoza+, 2009)J/ApJ/581/258 : Infrared photometry in the Arches Cluster (Figer+, 2002)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/751/132https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/751/132http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/751/132https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/751/132https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/751/132http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/751/132GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/751/132/table5 (Membership table for objects in the Arches Central field)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/751/132/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/751/132/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/751/132/table5?GETtext/xml+votable180.050000true266.46177583-28.822831390.0055555555555555566/28830https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/751/132?format=asciiInfrareddefaultJ/ApJ/751/132/table5Membership table for objects in the Arches Central fieldrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/432] Sequential star numbermeta.id;meta.mainintK'mag[10/20] Keck/NIRC2 K-prime apparent magnitudemagphot.mag;em.IR.KfloatDelX[-4.1/6.4] Position offset from reference star, East to West (1)arcsecpos.angDistance;arith.difffloatDelY[-6.9/3.4] Position offset from reference star, South to North (1)arcsecpos.angDistance;arith.difffloatpmX[-4.3/8.5] East to West proper motionmas/yrpos.pmfloate_pmX[0.06/0.5] The 1{sigma} error in pmXmas/yrstat.errorfloatpmY[-9.9/5.4] South to North proper motionmas/yrpos.pm;pos.eq.spdfloate_pmYThe 1{sigma} error in pmYmas/yrstat.errorfloatCMem[0/1] Cluster membership probabilitystat.probabilitydoubleFMem[0/1] Field membership probabilitystat.probability;obs.fielddoubleR[0/1] PSF reference star flag (2)meta.codeint_RAPosition computed from the position of the reference star measured on Fig.1 (17:45:50.618-28:49:18.25) and the offsets DelX, DelY (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from the position of the reference star measured on Fig.1 (17:45:50.618-28:49:18.25) and the offsets DelX, DelY (declination part)degpos.eq.dec;meta.main