A team from the University of Toronto has developed a map of 12 streams of stars orbiting within our galactic halo that may reveal the way in which dark matter holds the stars in their orbits, while also giving clues about the formation history of the Milky Way.

“We are seeing these streams being disrupted by the Milky Way’s gravitational pull and eventually becoming part of the Milky Way,” said Ting Li, an assistant professor and lead author on the new paper.

“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.”

A program called the Southern Stellar Stream Spectroscopic Survey (S5) was developed to measure the properties of stellar streams which are formed from the remains of neighbouring small galaxies and star clusters that are being torn apart by the Milky Way.

The speeds of the stars were measured using the four-metre...

Robert Heaton