This supernova is at least twice as bright and energetic as any other event of its kind ever recorded and is between 50 and 100 times the mass of the Sun.
A team of astronomers led by researchers at the University of Birmingham, England, detected the most brilliant and energetic supernova ever seen. The discovery was published in an article last Monday (13) in the journal Nature Astronomy.
A supernova is an astronomical event that happens at the end of the life of some types of stars. It is characterized by a very bright explosion that occurs quickly and also ends in a short period of time (weeks or months).
The event identified by the researchers is at least twice as bright and more energetic than any other event of its kind ever recorded. In addition, the researchers speculate that the star that produced the supernova was also extremely massive: between 50 and 100 times the mass of the Sun (normally, supernovae have between 8 and 15 solar masses).
“We can measure supernovae using two scales – the total energy of the explosion, and the amount of that energy that is emitted as observable light, or radiation,” explains Matt Nicholl, one of the researchers, in a statement. “In a typical supernova, the radiation is less than 1 per cent of the total energy. But in SN2016aps, we found the radiation was five times the explosion energy of a normal-sized supernova. This is the most light we have ever seen emitted by a supernova.”
According to the scientists, to be so bright, the explosion must have been much more energetic than usual. By examining the spectrum of light emitted by the event, the experts were able to prove that the supernova collided with a massive shell of gas in its surroundings, which amplified the explosion.
“Stars with extremely large mass undergo violent pulsations before they die, shaking off a giant gas shell. This can be powered by a process called the pair instability, which has been a topic of speculation for physicists for the last 50 years,” notes Nicholl. “If the supernova gets the timing right, it can catch up to this shell and release a huge amount of energy in the collision.”
SN2016aps also intrigues specialists for its composition: the gas detected was mainly hydrogen, which is unusual in stars the size of the one that originated the supernova. “One explanation is that two slightly less massive stars of around, say 60 solar masses, had merged before the explosion. The lower mass stars hold onto their hydrogen for longer, while their combined mass is high enough to trigger the pair instability,” speculates Nicholl.