The Andromeda Galaxy is surrounded by a swarm of small satellite galaxies. Researchers have detected a stream of stars in one of the Andromeda Galaxy’s outer satellite galaxies, a dwarf galaxy called Andromeda II. This galaxy is very small — less than one percent of the Milky Way. The movement of the stars tells us that what we are observing is the remnant of a merger between two dwarf galaxies. Mergers between galaxies of such low mass has not been observed before.
from Space & Time News — ScienceDaily http://ift.tt/MokNdw