By Nadia Drake
There are two ways to light a cosmic candle. One technique calls for two white dwarf stars; another positions a white dwarf near a larger stellar companion. Both combinations produce type 1a supernovas (pictured here), massive stellar explosions that act as “standard candles” for gauging astronomical distances.
Type 1a supernovas are triggered when white dwarfs gain weight, igniting a runaway thermonuclear reaction that destroys the dwarf, producing a fireball of predictable brightness. For a long time, astronomers disagreed over what sorts of ingredients were needed to make the white dwarf go boom.