Journal Article

A new model for the Milky Way bar

Yougang Wang, Hongsheng Zhao, Shude Mao and R. M. Rich

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 427, issue 2, pages 1429-1440
Published in print December 2012 | ISSN: 0035-8711
Published online December 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.22063.x
A new model for the Milky Way bar

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We use Schwarzschild's orbit-superposition technique to construct self-consistent models of the Galactic bar. Using χ2 minimization, we find that the best-fitting Galactic bar model has a pattern speed Ωp = 60 km s−1 kpc−1, disc mass Md = 1.0 × 1011 M and bar angle θbar = 20° for an adopted bar mass Mbar = 2 × 1010 M. The model can reproduce not only the three-dimensional and projected density distributions but also velocity and velocity dispersion data from the Bulge Radial Velocity Assay (BRAVA) survey. We also predict the proper motions in the range l = [−12°, 12°], b = [−10°, 10°], which appear to be higher than observations in the longitudinal direction. The model is stable within a time-scale of 0.5 Gyr, but appears to deviate from steady state on longer time-scales. Our model can be further tested by future observations such as those from GAIA.

Keywords: Galaxy: bulge; Galaxy: centre; Galaxy: formation; Galaxy: kinematics and dynamics; Galaxy: nucleus; Galaxy: structure

Journal Article.  7351 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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