ESA Integral catches dead star exploding in a Type 1a Supernova

Astronomers studying SN2014J, a Type Ia supernova discovered in January 2014, have found proof that this type of supernova is caused by a white dwarf star reigniting and exploding.

This finding was made by using ESA’s Integral observatory to detect gamma rays from the radioactive elements created during the explosion.

This sequence of artist's impressions shows some of the steps leading up to and following the explosion.

A white dwarf, a star that contain up to 1.4 times the mass of the Sun squeezed into a volume about the same size as the Earth, leeches matter from a companion star (image 1).

The Integral measurements suggest that a belt of gas from the companion star builds up around the equator of the white dwarf (image 2). 

This belt detonates (image 3) and triggers the internal explosion that becomes the supernova (image 4). 

Material from the explosion expands (image 5) and eventually becomes transparent to gamma rays (image 6).

Astronomers using ESA’s Integral gamma-ray observatory have demonstrated beyond doubt that dead stars known as white dwarfs can reignite and explode as supernovae.

The finding came after the unique signature of gamma rays from the radioactive elements created in one of these explosions was captured for the first time.

The explosions in question are known as Type Ia supernovae, long suspected to be the result of a white dwarf star blowing up because of a disruptive interaction with a companion star.

However, astronomers have lacked definitive evidence that a white dwarf was involved until now.

The ‘smoking gun’ in this case was evidence for radioactive nuclei being created by fusion during the thermonuclear explosion of the white dwarf star.

“Integral has all the capabilities to detect the signature of this fusion, but we had to wait for more than ten years for a once-in-a-lifetime opportunity to catch a nearby supernova,” says Eugene Churazov, from the Space Research Institute (IKI) in Moscow, Russia and the Max Planck Institute for Astrophysics,in Garching, Germany.

Although Type Ia supernovae are expected to occur frequently across the Universe they are rare occurrences in any one galaxy, with typical rates of one every few hundred years.