Gaia Data Release 2. Kinematics of globular clusters and dwarf galaxies around the Milky Way

Author(s): , A. Helmi, F. van Leeuwen, P. J. McMillan, D. Massari, T. Antoja, A. C. Robin, L. Lindegren, U. Bastian, F. Arenou, C. Babusiaux, M. Biermann, M. A. Breddels, D. Hobbs, C. Jordi, E. Pancino, C. Reylé, J. Veljanoski, A. G. A. Brown, A. Vallenari, T. Prusti, J. H. J. de Bruijne, C. A. L. Bailer-Jones, D. W. Evans, L. Eyer, F. Jansen, S. A. Klioner, U. Lammers, X. Luri, F. Mignard, C. Panem, D. Pourbaix, S. Randich, P. Sartoretti, H. I. Siddiqui, C. Soubiran, N. A. Walton, M. Cropper, R. Drimmel, D. Katz, M. G. Lattanzi, J. Bakker, C. Cacciari, J. Castañeda, L. Chaoul, N. Cheek, F. De Angeli, C. Fabricius, R. Guerra, T. Lebzelter, J. Alves
Abstract: Context. Aims. The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many different aspects of the dynamics of the satellites of the Milky Way. We focus here on determining the proper motions of 75 Galactic globular clusters, nine dwarf spheroidal galaxies, one ultra-faint system, and the Large and Small Magellanic Clouds. Methods. Using data extracted from the Gaia archive, we derived the proper motions and parallaxes for these systems, as well as their uncertainties. We demonstrate that the errors, statistical and systematic, are relatively well understood. We integrated the orbits of these objects in three different Galactic potentials, and characterised their properties. We present the derived proper motions, space velocities, and characteristic orbital parameters in various tables to facilitate their use by the astronomical community. Results. Our limited and straightforward analyses have allowed us for example to (i) determine absolute and very precise proper motions for globular clusters; (ii) detect clear rotation signatures in the proper motions of at least five globular clusters; (iii) show that the satellites of the Milky Way are all on high-inclination orbits, but that they do not share a single plane of motion; (iv) derive a lower limit for the mass of the Milky Way of 9.1 -2.6 +6.2 × 10 11 M âŠ based on the assumption that the Leo I dwarf spheroidal is bound; (v) derive a rotation curve for the Large Magellanic Cloud based solely on proper motions that is competitive with line-of-sight velocity curves, now using many orders of magnitude more sources; and (vi) unveil the dynamical effect of the bar on the motions of stars in the Large Magellanic Cloud. Conclusions. All these results highlight the incredible power of the Gaia astrometric mission, and in particular of its second data release.
Organisation(s): Department of Astrophysics
External organisation(s): University of Groningen, University of Cambridge, Lund Observatory, Science and Operations Department - Science Division (SCI-SC), University of Barcelona, Université de Franche-Comté, Scientific Software Center, Université Paris VII - Paris-Diderot, Centre National De La Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri, Space Science Data Center (SSDC) - Agenzia Spaziale Italiana (ASI), Leiden University, Osservatorio Astronomico, Max-Planck-Institut für Astronomie, Université de Genève, Technische Universität Dresden, European Space Astronomy Centre (ESA), Université Côte d'Azur, Centre national d'études spatiales (CNES), Université Libre de Bruxelles, Fund for Scientific Research, Université Bordeaux, University College London, INAF-Osservatorio Astrofisico di Torino, INAF-Osservatorio Astronomico di Bologna
Journal: Astronomy & Astrophysics
Volume: 616
No. of pages: 47
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201832698
Publication date: 08-2018
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/f8b0da65-3396-41ab-bc9e-21b2e20d8e06

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