Astronomers Witness the Heart of an Exploding Star in a Binary System

Astronomers have now seen right to the heart of an exploding star, thanks to a combination of data from telescopes. The findings reveal a highly-detailed look at exactly what happens when a star in a binary system hurls material into space.

Scientists used highly-detailed images with radio telescopes from across Europe and America in order to pinpoint the locations where a stellar explosion, called a nova, emitted gamma rays. This, in particular, revealed how gamma-ray emissions were produced.

"We not only found where the gamma rays came from, but also got a look at a previously-unseen scenario that may be common in other nova explosions," said Laura Chomiuk, one of the researchers, in a news release.

A nova occurs when gas from a companion star falls onto the surface of a white dwarf star in a binary system. This falling material triggers a thermonuclear explosion on the surface of the star that blasts the gas into space at speeds of millions of miles per hour. These explosions can be bright enough to give the illusion that there's a new star in the sky. Because these explosions are unpredictable, though, they're difficult to study.

In this case, though, the researchers were at the right place at the right time. NASA's Fermi spacecraft detected gamma rays coming from a nova called V959 Mon, located about 6,500 light-years from Earth. At the same time, telescopes on Earth detected radio waves coming from the nova.

"By watching this system over time and seeing how the pattern of radio emission changed, then tracing the movements of the knots, we saw the exact behavior expected of this scenario," said Chomiuk.

What's more interesting is that because this type of ejection is also seen in other binary-star systems, this research could help shed light on how these systems develop.

"We may be able to use novae as a 'testbed' for improving our understanding of this critical stage of binary evolution," said Chomiuk.

The findings are published in the journal Nature.