... Stars . ... To understand what has happened we need to consider an often-overlooked class of object, the white dwarfs. New research shows that some old stars known as white dwarfs might be held up by their rapid spins, and when they slow down, they explode as Type Ia supernovae. ... However, give a white dwarf a very close companion star and you could have an explosion visible across the Universe. ... This, however, is not the only catastrophe that can befall such a white dwarf star. ...