Astronomers are one step closer to revealing the properties of dark matter enveloping our Milky Way galaxy, thanks to a new map of twelve streams of stars orbiting within our galactic halo.
Understanding these star streams is very important for astronomers. As well as revealing the dark matter that holds the stars in their orbits, they also tell us about the formation history of the Milky Way, revealing that the Milky Way has steadily grown over billions of years by shredding and consuming smaller stellar systems.
"We are seeing these streams being disrupted by the Milky Way's gravitational pull, and eventually becoming part of the Milky Way. This study gives us a snapshot of the Milky Way's feeding habits, such as what kinds of smaller stellar systems it 'eats'. As our galaxy is getting older, it is getting fatter," said University of Toronto Professor Ting Li, the lead author of the paper.
Prof. Li and her international team of collaborators initiated a dedicated program -- the Southern Stellar Stream Spectroscopic Survey (S5) -- to measure the properties of stellar streams: the shredded remains of neighboring small galaxies and star clusters that are being torn apart by our own Milky Way.