Dead Stars 'Re-ignite' to go Supernova

In the case of supernovae, it was long thought that dying white dwarf stars were left out of the equation, simply too small to spark the awe-inspiring explosion. Now researchers believe they figured out how some stars managed to still pull off the self-destructive stunt - re-igniting with the help of a nearby buddy.

A study recently published in the journal Nature details how white dwarfs paired with a dying companion star can still go supernova in what appears to be a bizarre stellar suicide pact.

According to the study, white dwarfs form when a small, dying star begins to spin down, losing its outer layers of solar mass. Left alone, this shrinking dwarf will just cool down more and more over time. However, white dwarfs have a tipping point - known as the Chandrasekhar limit.

This limit is easily broken when a white dwarf begins to steal solar matter from a dying companion star in the same system, or when colliding with another white dwarf. The resulting instability causes what astronomers call a "type la supernova."

According to BBC News, researchers at the University College London's teaching observatory at Mill Hill in the United Kingdom detected a type Ia supernova in the nearby galaxy M82 a mere two months ago, providing a rare opportunity to study this remarkable event.

The researchers closely observed gamma-ray emissions that are theorized to be specific to this type of star explosion. According to their analysis, the expanding debris of the supernova had already expanded to a size larger than our entire solar system.

Study author Eugene Churazov added, however, that how exactly this la supernova occurred remains a mystery. Only its existence has been proven.

"It is perfectly consistent with the simplest scenario, of a single white dwarf with a mass close to the Chandrasekhar limit," he told BBC. "But we cannot exclude with this data that this event was caused by a merger [of two white dwarfs]."