The Imprints of the Galactic Bar on the Thick Disk with Rave
Journal
Date Issued
2015
Author(s)
Antoja, T.
•
Monari, G.
•
Helmi, A.
•
Bienaymé, O.
•
Bland-Hawthorn, J.
•
Famaey, B.
•
Gibson, B. K.
•
Grebel, E. K.
•
Kordopatis, G.
•
•
Navarro, J.
•
Parker, Q.
•
Reid, W. A.
•
Seabroke, G.
•
Steinmetz, M.
•
Zwitter, T.
Description
T.A. is supported by an ESA Research Fellowship in Space Science. We thank Ralf Scholz for constructive comments on the analysis. A.H. was partially supported by ERC-StG GALACTICA-240271. G.M. is supported by the Centre National d ’ Etudes Spatiales (CNES). Funding for RAVE has been provided by the Anglo-Australian Observatory; the Leibniz-Institut fuer Astrophysik Potsdam; the Australian National University; the Australian Research Council; the French National Research Agency; the German Research foundation; the Istituto Nazionale di Astrofisica at Padova; The Johns Hopkins University; the National Science Foundation of the USA (AST-0908326); the W.M. Keck foundation; the Macquarie University; The Netherlands Research School for Astronomy; the Natural Sciences and Engineering Research Council of Canada; the Slovenian Research Agency; the Swiss National Science Foundation; the Science Technology Facilities Council of the UK; Opticon; Strasbourg Observatory; and the Universities of Groningen, Heidelberg, and Sydney. The RAVE website is http://rave-survey.org. We thank the anonymous referee for helpful comments.
Abstract
We study the kinematics of a local sample of stars, located within a cylinder of 500 pc radius centered on the Sun, in the RAVE data set. We find clear asymmetries in the {{v}R} - {{v}φ } velocity distributions of thin and thick disk stars: there are more stars moving radially outward for low azimuthal velocities and more radially inward for high azimuthal velocities. Such asymmetries have been previously reported for the thin disk as being due to the Galactic bar, but this is the first time that the same type of structures are seen in the thick disk. Our findings imply that the velocities of thick-disk stars should no longer be described by Schwarzschild’s, multivariate Gaussian or purely axisymmetric distributions. Furthermore, the nature of previously reported substructures in the thick disk needs to be revisited as these could be associated with dynamical resonances rather than to accretion events. It is clear that dynamical models of the Galaxy must fit the 3D velocity distributions of the disks, rather than the projected 1D, if we are to understand the Galaxy fully.
Volume
800
Issue
2
Start page
L32
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...800L..32A
Rights
open.access
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