white dwarf

A white dwarf is a small star that has used up most or all of its nuclear fuel and has collapsed into a very small and very dense star. Left alone, a white dwarf will sit in space and radiate off the remainder of its heat. However, white dwarfs that are in a binary star system can begin to gather matter from its companion star. When enough matter is gathered, the white dwarf star can restart its process of nuclear fusion causing an explosion. This explosion is called a nova. On rare occasions, a white dwarf will explode more than once and is called a “recurring nova.”