The Gaia Sausage and the Last Major Invasion of the Milky Way

Dr. N. W. Evans (host Ferrer), Cambridge
September 19, 2018 at 4:00 pm
204 Crow
Event Description 

The Gaia satellite, which is providing the positions, velocities and chemical properties of over a billion stars in the Milky Way Galaxy, is transforming our understanding of Galactic structure. We will present evidence that there was an ancient and dramatic head-on collision between the Milky Way Galaxy and a smaller object, dubbed the Sausage Galaxy. This is so called because the paths of the stars from the merger are strongly radial and form a sausage shape in phase space. This defining event in the history of the Milky Way Galaxy created the thick disk and the stellar halo. We discuss implications of this result for the assembly history of the Milky Way, the chemistry and kinematics of nearby stars, as well as the distribution of dark matter and implications for direct detection experiments.

Coffee: 3:30 pm, 245 Compton