NASA Hubble Spots 'Zombie' Star After Supernova Explosion

NASA's Hubble Space Telescope has made a surprising discovery. It's spotted a star system that may have left behind a "zombie star" after a supernova explosion that should have destroyed it.

A supernova occurs when a dying star essentially explodes. In the case of white dwarfs, it usually obliterates the star. Yet it turns out that in this case, a faint supernova may have actually left behind a surviving part of the dwarf star-essentially, a zombie star.

The supernova that occurred is what is known as Iax, which is less common than its brighter counterpart, a Type Ia supernova. So far, astronomers have identified only about 30 of Type Iax supernovas, which all might leave behind a surviving white dwarf star.

"Astronomers have been searching for decades for the star systems that produce Type IA supernova explosions," said Surabh Jha, one of the researchers, in a news release. "Type Ia's are important because they're used to measure vast cosmic distances and the expansion of the universe. But we have very few constraints on how any white dwarf explodes. The similarities between Type Iax's and normal Type Ia's make understanding Type Iax progenitors important, especially because no Type Ia progenitor has been conclusively identified. This discovery shows us one way that you can get a white dwarf explosion."

The newly discovered supernova is called SN 2012Z, and is located in the galaxy NGC 1309. While discovering the supernova was interesting in and of itself, what was more fascinating was that there was an object near the location of the supernova-a companion, helium star. Currently, the scientists plan to use Hubble again in 2015 to observe the area where the supernova occurred in order to confirm whether or not there is a zombie star and helium companion.

"Because these supernovae don't destroy the white dwarf completely, we surmise that some of these explosions eject a little bit and some eject a whole lot," said Ryan Foley, one of the researchers.

The findings are published in the journal Nature.