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(Jan. 4) Dynamics of the Milky Way Bulge and its X-shaped Structure

Last updated :2018-01-02

Topic: Dynamics of the Milky Way Bulge and its X-shaped Structure
Speaker: Prof. Juntai Shen
(Shanghai Astronomical Observatory of Chinese Academy of Sciences)
Invited by: Prof. LIN Weipeng
Time: 15:00-16:00, Thursday, January 4, 2018
Venue: Room 107, Red House 17, Zhuhai Campus, SYSU

Abstract:
Recent years have witnessed a gradual paradigm shift in the formation and evolution of the Galactic bulge. Bulges were commonly believed to form in the dynamical violence of galaxy mergers. However, it has become increasingly clear that the main body of the Milky Way bulge is not a classical bulge made by previous major mergers, instead it appears to be a bar seen somewhat end-on. The Milky Way bar can form naturally from a precursor disc and thicken vertically by the internal firehose/buckling instability, giving rise to the boxy appearance. This picture is supported by many lines of evidence, including the asymmetric parallelogram shape, the strong cylindrical rotation, the existence of an intriguing X-shaped structure in the bulge, and perhaps the vertical metallicity gradient. I will also review modelling of the gas flow pattern induced by the Milky Way bar and spirals.