Although neighboring Andromeda Galaxy may look tranquil, scientists are realizing the extent of its tumultuous history. After taking the widest survey yet of faint stars in Andromeda’s neighborhood, a team of astronomers led by Alan McConnachie at the NRC Herzberg Institute of Astrophysics in Victoria, British Columbia, discovered signs of ancient mergers and near-collisions with smaller galaxies, all of which helped shape the Andromeda we see today.
The study reveals the streams of stars and dwarf galaxies left over from past collisions and sheds light on the evolution of large galaxies and the satellites that revolve around them.