The M81 Group, containing the well known galaxies Messier 81 and Messier 82, is a group of galaxies within the constellation Ursa Major. Along with Messier 81 and 82 are several other galaxies with apparent brightness. The center, located at an approximate distance of 3.6 Mpc, is one of the nearest groups to the Local Group. The total estimated mass of the group is (1.03 Â± 0.17) Ã— 1012Mâ˜‰. The Virgo Supercluster contains the M81 Group, the Local Group, and some other nearby groups.
Messier 81, Messier 82, and NGC 3077 are all strongly interacting with each other. Due to gravitational interactions hydrogen gas has been stripped away forming filamentary gas structures within the group. Within the center of Messier 82 and NGC 3077 interstellar gas has fallen into their centers and caused strong starburst activity.