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dc.contributor.authorvan der Marel, Roeland P.
dc.contributor.authorFardal, Mark A.
dc.contributor.authorSohn, Sangmo Tony
dc.contributor.authorPatel, Ekta
dc.contributor.authorBesla, Gurtina
dc.contributor.authorPino, Andrés del
dc.contributor.authorSahlmann, Johannes
dc.contributor.authorWatkins, Laura L.
dc.date.accessioned2019-06-13T20:03:43Z
dc.date.available2019-06-13T20:03:43Z
dc.date.issued2019-02-10
dc.identifier.citationRoeland P. van der Marel et al 2019 ApJ 872 24en_US
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/1538-4357/ab001b
dc.identifier.urihttp://hdl.handle.net/10150/632889
dc.description.abstractThe 3D velocities of M31 and M33 are important for understanding the evolution and cosmological context of the Local Group. Their most massive stars are detected by Gaia, and we use Data Release 2 (DR2) to determine the galaxy proper motions (PMs). We select galaxy members based on, e.g., parallax, PM, color-magnitude diagram location, and local stellar density. The PM rotation of both galaxies is confidently detected, consistent with the known line-of-sight rotation curves: V-rot = -206 +/- 86 km s(-1) (counterclockwise) for M31, and V-rot = 80 +/- 52 km s(-1) (clockwise) for M33. We measure the center-of-mass PM of each galaxy relative to surrounding background quasars in DR2. This yields that (mu(alpha*), mu(delta)) equals (65 +/- 18, -57 +/- 15) mu as yr(-1) for M31 and (31 +/- 19, -29 +/- 16) mu as yr(-1) for M33. In addition to the listed random errors, each component has an additional residual systematic error of 16 mu as yr(-1). These results are consistent at 0.8 sigma and 1.0 sigma with the (2 and 3 times higher accuracy) measurements already available from Hubble Space Telescope (HST) optical imaging and Very Long Baseline Array water maser observations, respectively. This lends confidence that all these measurements are robust. The new results imply that the M31 orbit toward the Milky Way (MW) is somewhat less radial than previously inferred, V-tan,V-DR2 +/- HST = 57(-31)(+35) km s(-1), and strengthen arguments that M33 may be on its first infall into M31. The results highlight the future potential of Gaia for PM studies beyond the MW satellite system.en_US
dc.language.isoenen_US
dc.publisherIOP PUBLISHING LTDen_US
dc.relation.urlhttp://stacks.iop.org/0004-637X/872/i=1/a=24?key=crossref.77eed68e5832879642e2a6b74dae2ee2en_US
dc.rights© 2019. The American Astronomical Society. All rights reserved.en_US
dc.subjectgalaxies: kinematics and dynamicsen_US
dc.subjectLocal Groupen_US
dc.subjectproper motionsen_US
dc.titleFirst Gaia Dynamics of the Andromeda System: DR2 Proper Motions, Orbits, and Rotation of M31 and M33en_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.volume872
dc.source.issue1
dc.source.beginpage24
refterms.dateFOA2019-06-13T20:03:44Z


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