A combined view of visible and x-ray light from a pair of NASA telescopes has helped astronomers solve a cosmic mystery: What caused the brilliant supernova that left behind this bubble in space?
Astronomers already knew that the supernova remnant 0509-67.5, seen above, is the product of what's called a Type Ia supernova, which involves a white dwarf star becoming so massive that it explodes. The most common explanation for a Type Ia is that a white dwarf gains mass by siphoning matter from a companion star.
But in this case, the sharp eyes of the Hubble Space Telescope and the Chandra X-ray Observatory couldn't find any trace of such a companion. Instead, astronomers think that SNR 0509-67.5 was formed when two tightly orbiting white dwarfs spiraled in toward each other and collided, destroying both stars in a cataclysmic blast.