Monday, February 23, 2009

Milky Way still ringing from an impact 2 GYA

New Scientist has an article about a computer simulation created by Ivan Minchev of the University of Strasbourg, France of the distribution of velocities of billions of Milky Way stars.  From the model, a pattern of "ripples" emerged; streams of stars at high velocity. He suggests these stars were jolted by a shock wave from another galaxy merging with ours about 2 billion years ago.

[0902.1531] Is the Milky Way ringing? The hunt for high velocity streams
By matching the number and positions of the observed streams, we estimate that the Milky Way disk was strongly perturbed ~1.9 Gyr ago. This event could have been associated with Galactic bar formation.

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