Astronomers have discovered nearly a dozen new stellar rivers—strings of moving stars—over the disk of the Milky Way. The streams, which seem to represent smaller galaxies torn apart by our own, come from scans of the velocities of about a quarter million stars in our galaxy made for the Sloan Digital Sky Survey. Prior scans had turned up a few narrow rivers such as one extending from the star cluster NGC 5466, 76,000 light-years away, that covers 45 degrees across the northern sky. The 11 new entries form a tangle that's harder to separate. Researchers believe that the streams arose separately when neighboring star clusters known as dwarf galaxies were drawn apart like taffy by the Milky Way's larger gravitational field. They say the new findings, reported at a conference this week, could be used to improve models of galaxies colliding with and cannibalizing one another.
