Comet Enthusiast

U.S. astronomers studying the Andromeda galaxy says a thick stellar disk of older stars offers clues to how large spiral galaxies like the Milky Way form.

UCLA research astronomer Michael Rich and colleagues from Europe and Australia, using the Keck Telescope in Hawaii, say about 70 percent of stars in the Andromeda galaxy are contained within a thin, flat disk surrounding a central bulge of older stars at the center of the galaxy, a UCLA release said Tuesday.