There are different types of supernova explosions. Type Ia supernovae, also known as thermonuclear supernovae, occur in binary star systems. To trigger a type Ia supernova, one of the two stars must be a white dwarf. The other star is often a low-mass star, like our Sun, or can be a red giant star. Type Ia supernovae signal the complete destruction of a white dwarf, leaving nothing behind. So when astronomers went to look at the site of the supernova...
