Aust'n-U.S. astronomers glimpse supernova shockwave of "nuclear bomb" proportions

A team of Australian and U.S. astronomers have caught the earliest glimpse of two supernovas exploding in outer space, which they have likened to watching a nuclear bomb blast.

Details of the discovery, which have been accepted by the Astrophysical Journal for publication, will help scientists gain a better understanding of the life cycle of stars, according to the study's co-author, Dr Brad Tucker of the Australian National University (ANU).

The cosmic event's chain reaction could also prove vital for scientists' understanding of the elements planet earth needed to spawn and sustain life.

Of the two supernovas, viewed through NASA's Kepler Space Telescope, only the smaller 'red supergiant' produced a fully-fledged, visible supernova.

A supernova takes place when an ageing star runs out of fuel, leading to the total collapse of its core.

"It's like packing in dirt," Tucker told the Australian Broadcasting Corporation (ABC) on Tuesday.

"You keep pressing it till it's so dense you can't get it in anymore, and that's when you create a neutron star."

"But you reach a limit when you can't pack it in anymore, and that force pushing in bounces back and it triggers a shockwave to go through the star, causing the star to actually blow up."

Tucker said the first dying star, which they believe is about 270 times the radius of the sun and 750 million lightyears away from earth, put on a spectacular show.

"It's like the shockwave from a nuclear bomb, only much bigger, and no one gets hurt," Tucker, who works in the university's Research School of Astronomy and Astrophysics, said in a press release on Tuesday.

Astronomers have witnessed this cosmic event, which typically only lasts for hours or days, before with the aid of X-ray vision. But Tucker's team left nothing to chance, with NASA's space telescope giving them the ability to monitor changes in the universe every 30 minutes.

"(The first discoverers) were actually looking at another exploding star and one happened to go right off in the exact patch of sky in the exact moment they were looking at it. It was the definition of luck," Tucker said.

"This is the first time we've seen this in the normal visible colours, and we now know it happens."

The study concluded that the second star, almost twice the size of the smaller one, did in fact experience a supernova but the shockwave did not reach its exterior. Endit