M81, in the constellation of Ursa Major, is one of the galaxies closest to our Local Group and interacts gravitationally with its neighbours M82 and NGC 3077, influencing the structure of all three galaxies.

M82 exhibits intense star formation in its core, triggered by this interaction, at a rate approximately 10 times higher than that of the Milky Way. A powerful “superwind” of ionized gas emerges from its centre, expelled perpendicular to the galactic disk by the energy released by young stars and supernova explosions.