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A new model for the Milky Way bar

Published online by Cambridge University Press:  05 March 2015

Yougang Wang ,
Hongsheng Zhao ,
Shude Mao  and
R. M. Rich
Yougang Wang*
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
Hongsheng Zhao
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China SUPA, University of St Andrews, KY16 9SS, UK Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
Shude Mao
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL, UK
R. M. Rich
Affiliation:
Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1562, USA
*
†email: wangyg@bao.ac.cn
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Abstract

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We use Schwarzschild's orbit-superposition technique to construct self-consistent models of the Galactic bar. Using χ2 minimisation, we find that the best-fit Galactic bar model has a pattern speed Ωp=60 km s−1 kpc−1, disk mass Md=1.0×1011M⊙ and bar angle θbar=20° for an adopted bar mass Mbar=2×1010M⊙. The model can reproduce not only the three-dimensional and projected density distributions but also velocity and velocity dispersion data from the 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 timescale of 0.5 Gyr, but appears to deviate from steady-state on longer timescales. Our model can be further tested by future observations such as those from GAIA.

Keywords

Galaxy: bulge - Galaxy: centre - Galaxy: kinematics and dynamics
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 10 , Highlights H16: Highlights of Astronomy , August 2012 , pp. 350
Copyright
Copyright © International Astronomical Union 2015