was capturing mass from its companion star. When the white dwarf had gathered enough mass and was no longer able to support itself, the star detonated in a violent and extremely bright explosion. Since a supernova occurs in a typical spiral galaxy (roughly) once every 100 years, astronomers have software continuously monitor high-resolution automatic survey camera images of galaxies like NGC 3982, for early detection of supernova explosions. References External links Spiral Galaxy NGC 3982 @ SEDS NGC objects pages NGC 3982 at ESA/Hubble Circumnuclear Star Forming Activity in NGC 3982 Intermediate spiral galaxies M109 Group Ursa Major (constellation) 3982 06918 037520 17890414