Astronomers have discovered a new type of supernova. A Type Ia occurs when a white dwarf, pulling material from a companion star, reaches a limit and blows itself apart. In Type Iax supernovae, however, the explosion is much smaller; the white dwarf may even survive the blast. Astronomers don't yet understand exactly it works.
Type I supernovae, by the way, are detonations and destructions of stars many times more massive than the Sun.