Messier 87
The stars in this galaxy form about one sixth of Messier 87's mass. They are spread out symmetrically, but the density of stars decreases with distance from the core. The galactic envelope extends out to a radius of about , where it stops—possibly cut off by an encounter with another galaxy. Between the stars is a diffuse interstellar medium of gas that has been chemically enriched by elements emitted from evolved stars.