London: Astronomers have discovered the oldest supernovae ever detected - two massive stars that exploded 12.5billion years ago.
The cataclysmic events are known as ‘superluminous’ supernovae, and are up to 100 times brighter than other types of stellar blasts, they reported online in Nature.
They happened only 1.5 billion years after the Big Bang, which occurred 14 billion years ago, and their detection could eventually lead to finding the first stars that detonated, they said.
The record easily beats the previous most distant supernova found that was 11 billion years old.
Superluminous supernovae were discovered only a few years ago and are rare in the nearby Universe.
Some are believed to occur when enormous stars undergo a nuclear explosion caused by light particles converting into electron-positron pairs - beams of matter and anti-matter heading in opposite directions.
Such events probably happened more often in the early universe when massive stars were more common.
This and their extreme brightness encouraged Dr Jeff Cooke and colleagues to search for superluminous supernovae when the Universe was less than four billion years old.
Using images from the giant Canada-France-Hawaii Telescope (CFHT) the researchers calculated superluminous supernovae were at least ten times more common then than now.
“Here we report the detection of two superluminous supernovae that have slowly evolving light curves,” the paper quoted Dr Cooke, of Swinburne University of Technology in Melbourne, as saying.
“The detection presents the possibility of finding the explosions of the first stars to form after the Big Bang,” he added.