J/ApJ/840/30ivo://CDS.VizieR/J/ApJ/840/30doi:10.26093/cds/vizier.18400030CDSFritz T.K.Linden S.T.Zivick P.Kallivayalil N.Beaton R.L.Bovy J.,Sales L.V.Sohn T.Angell D.Boylan-Kolchin M.Carrasco E.R.Damke G.,Davies R.Majewski S.Neichel B.van der Marel R.2019-10-10T12:51:53Z2018-01-19T13:02:03ZCDS support team

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

cds-question@unistra.frglobular-star-clustersproper-motionsinfrared-photometryhst-photometryWe present a proper motion measurement for the halo globular cluster Pyxis, using Hubble Space Telescope/ACS data as the first epoch and GeMS/GSAOI Adaptive Optics data as the second, separated by a baseline of ~5 years. This is both the first measurement of the proper motion of Pyxis and the first calibration and use of Multi-Conjugate Adaptive Optics data to measure an absolute proper motion for a faint, distant halo object. Consequently, we present our analysis of the Adaptive Optics data in detail. We obtain a proper motion of {mu}_{alpha}_cos({delta})=1.09+/-0.31mas/yr and {mu}_{delta}_=0.68+/-0.29mas/yr. From the proper motion and line-of-sight velocity, we find that the orbit of Pyxis is rather eccentric, with its apocenter at more than 100kpc and its pericenter at about 30kpc. We also investigate two literature-proposed associations for Pyxis with the recently discovered ATLAS stream and the Magellanic system. Combining our measurements with dynamical modeling and cosmological numerical simulations, we find it unlikely Pyxis is associated with either system. We examine other Milky Way satellites for possible association using the orbit, eccentricity, metallicity, and age as constraints and find no likely matches in satellites down to the mass of Leo II. We propose that Pyxis probably originated in an unknown galaxy, which today is fully disrupted. Assuming that Pyxis is bound and not on a first approach, we derive a 68% lower limit on the mass of the Milky Way of 0.95x10^12^M_{sun}_.2017ApJ...840...30Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/840/30CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/195 : Globular Clusters in the Milky Way (Harris, 1996)J/AJ/118/1671 : Fornax cluster 4 VI photometry (Buonanno+, 1999)J/MNRAS/360/185 : VI photometry of the Leo II galaxy (Bellazzini+, 2005)J/A+A/459/423 : VI and [Fe/H] of Fornax dSph RGB stars (Battaglia+, 2006)J/A+A/465/815 : Abundances of Sgr dSph stars (Sbordone+, 2007)J/ApJ/684/1143 : BHB candidates in the Milky Way (Xue+, 2008)J/ApJ/690/1236 : COSMOS photometric redshift catalog (Ilbert+, 2009)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/A+A/540/A27 : Spectroscopy in Galactic globular clusters (Saviane+, 2012)J/ApJS/206/10 : CANDELS multiwavelength catalog (Galametz+, 2013)J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)J/ApJ/797/115 : HSTPROMO I. Observations and NGC7078 results (Bellini+, 2014)J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)J/ApJ/805/189 : Highly likely members of the Sgr stream (Hyde+, 2015)J/AJ/149/42 : Proper motion of Draco dwarf galaxy from HST (Pryor+, 2015)J/ApJ/809/59 : Ophiuchus stellar stream with PS1 data (Sesar+, 2015)J/ApJ/830/17 : GC secondary IR astrometric standards (Boehle+, 2016)J/A+A/595/L2 : Proper motions in NGC6681 globular cluster (Massari+, 2016)J/ApJ/818/99 : Globular cluster populations in S4G gal. II. (Zaritsky+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/840/30https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/840/30http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/840/30https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/840/30https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/840/30http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/840/30GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/840/30/table4 (Relative stellar proper motions)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/840/30/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/840/30/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/840/30/table4?GETtext/xml+votable180.050000true136.9898206-37.29828950.005555555555555556Cone search capability for table J/ApJ/840/30/table2 (*Potential moving group members)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/840/30/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/840/30/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/840/30/table2?GETtext/xml+votable180.050000true137.0073024-37.20815520.0055555555555555566/39954https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/840/30?format=asciiInfrareddefaultJ/ApJ/840/30/table4Relative stellar proper motionsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/421] Identifiermeta.id;meta.mainintprimaryGindicates a potential moving group member (table 2)meta.ref.urlcharMmMember? ("Member": 218 occurrences, "Non-Member": 129 occurrences or "Unclear")meta.code.membercharRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainpmRA[-14.5/2.7] Proper motion along RAmas/yrpos.pm;pos.eq.rafloate_pmRA[0.08/1.6] Uncertainty in pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDE[-5.5/8] Proper motion along DEmas/yrpos.pm;pos.eq.decfloate_pmDE[0.08/1.6] Uncertainty in pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatKmag[15.4/22.6] Gemini K' band magnitudemagphot.mag;em.IR.KfloatC1[-6/9.2]? HST (F606W-F814W) color index (1)magphot.color;em.opt.V;em.opt.IfloatnullableC2[0.7/11] The (F814W-K') color indexphot.color;em.IR;em.IRfloatSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJ/840/30/table2*Potential moving group membersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[33/405] Identifiermeta.id;meta.mainintRAJ2000Right ascension in decimal degrees (J2000) (1)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000) (1)degpos.eq.dec;meta.maindelXDistance {delta}_X_ from star 33arcsecpos.eq.ra;arith.difffloatdelYDistance {delta}_Y_ from star 33arcsecpos.eq.dec;arith.difffloatpmRA[-11.7/-10.4] Proper motion along RAmas/yrpos.pm;pos.eq.rafloate_pmRA[0.08/0.2] Uncertainty in pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDE[7/8] Proper motion along DEmas/yrpos.pm;pos.eq.decfloate_pmDE[0.08/0.2] Uncertainty in pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatKmag[15.4/18.1] Gemini K' band magnitudephot.mag;em.IR.KfloatC2[1.7/2.2] The (F814W-K') color indexphot.color;em.IR;em.IRfloat