White dwarf stars formed mysterious supernova

Supernova 2014J is 11 million light years away from earth and was only seen by chance at the University of London Observatory this year.

But understanding the mystery of the Supernova 2014J, which is a giant star explosion, will provide key information about the universe, including how it is expanding and how galaxies evolve, research shows.

To unlock how the supernova was formed, researchers used vast networks of radio telescopes across Europe including seven telescopes from the University of Manchester to obtain extremely deep images.

The images revealed a lack of radio emission from the supernova. "This meant that the merger of two white dwarf stars was the most likely cause of the supernova," said Rob Beswick from the University of Manchester.

White dwarfs are the inner core of a star once it has run out of nuclear fuel and ejected its outer layers.

A white dwarf star can explode if its mass increases to about 1.4 times that of the sun.

At this point, its core starts to undergo nuclear fusion.

This spreads rapidly through the star resulting in a huge thermonuclear explosion, which rips the star apart, causing it to appear like a brilliant new star shining billions of times brighter than the sun.

For decades there has been a dispute about how this explosion happens but these new results rule out the vast majority of models and point to the white dwarf theory.

"It is likely that more than a hundred years will pass until we see another such supernova so close to us. This was an amazing opportunity," Beswick added.

The research was published in the latest issue of the Astrophysical Journal.