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dc.contributor.authorSohn, Sangmo Tony
dc.contributor.authorWatkins, Laura L.
dc.contributor.authorFardal, Mark A.
dc.contributor.authorvan der Marel, Roeland P.
dc.contributor.authorDeason, Alis J.
dc.contributor.authorBesla, Gurtina
dc.contributor.authorBellini, Andrea
dc.date.accessioned2018-10-26T19:09:07Z
dc.date.available2018-10-26T19:09:07Z
dc.date.issued2018-07-20
dc.identifier.citationSangmo Tony Sohn et al 2018 ApJ 862 52en_US
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/1538-4357/aacd0b
dc.identifier.urihttp://hdl.handle.net/10150/630572
dc.description.abstractWe present Hubble Space Telescope (HST) absolute proper motion (PM) measurements for 20 globular clusters (GCs) in the Milky Way (MW) halo at Galactocentric distances R-GC approximate to 10-100 kpc, with a median per-coordinate PM uncertainty of 0.06 mas yr(-1). Young and old halo GCs do not show systematic differences in their 3D Galactocentric velocities, derived from combining existing line-of-sight velocities. We confirm the association of Arp 2, Pal 12, Terzan 7, and Terzan 8 with Sgr. These clusters and NGC 6101 have tangential velocity v(tan) > 290 km s(-1), whereas all other clusters have v(tan) < 200 km s(-1). NGC 2419, the most distant GC in our sample, is also likely associated with the Sgr stream, whereas NGC 4147, NGC 5024, and NGC 5053 definitely are not. We use the distribution of orbital parameters derived using the 3D velocities to separate halo GCs that either formed within the MW or were accreted. We also assess the specific formation history of, e.g., Pyxis and Terzan 8. We constrain the MW mass via an estimator that considers the full 6D phase-space information for 16 of the GCs from R-GC = 10 to 40 kpc. The velocity dispersion anisotropy parameter beta = 0.609(-0.229)(+0.130). The enclosed mass M(<39.5 kpc) = 0.61(-0.12)(+0.18) x 10(12) M-circle dot, and the virial mass M-vir 2.05(-0.79)(+0.97) 10(12) M-circle dot. These are consistent with, but on the high side among, recent mass estimates in the literature.en_US
dc.description.sponsorshipNASA from the Space Telescope Science Institute (STScI) [GO-14235, GO-12564, AR-15017]; NASA [NAS5-26555]; Royal Society University Research Fellowship; STFC [ST/P000541/1]en_US
dc.language.isoenen_US
dc.publisherIOP PUBLISHING LTDen_US
dc.relation.urlhttp://stacks.iop.org/0004-637X/862/i=1/a=52?key=crossref.e4879283300a618151a8be5f5bd791eeen_US
dc.rights© 2018. The American Astronomical Society. All rights reserved.en_US
dc.subjectastrometryen_US
dc.subjectGalaxy: haloen_US
dc.subjectGalaxy: kinematics and dynamicsen_US
dc.subject(Galaxy:) globular clusters: generalen_US
dc.subjectproper motionsen_US
dc.titleAbsolute Hubble Space Telescope Proper Motion (HSTPROMO) of Distant Milky Way Globular Clusters: Galactocentric Space Velocities and the Milky Way Massen_US
dc.typeArticleen_US
dc.contributor.departmentUniv Arizona, Dept Astronen_US
dc.identifier.journalASTROPHYSICAL JOURNALen_US
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en_US
dc.eprint.versionFinal published versionen_US
dc.source.journaltitleThe Astrophysical Journal
dc.source.volume862
dc.source.issue1
dc.source.beginpage52
refterms.dateFOA2018-10-26T19:09:08Z


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