August 6, 2014: Supernovae are the most powerful stellar explosions in the universe. Some of them are produced by the detonation of a white dwarf, the stripped-down core of an ordinary star at the end of its life. But 12 years ago, astronomers began noticing weak stellar blasts, a kind of mini-supernova. When one such explosion occurred in the galaxy NGC 1309, astronomers looking through Hubble archival images found for the first time the star system that produced the supernova blast of a white dwarf.
The inset panel from 2013 shows the supernova; archival Hubble data from 2005 and 2006 show the progenitor system for the supernova, thought to be a binary system containing a helium star transferring material to a white dwarf that exploded.See the rest: