They identified two supernovae – suicide stars that blow themselves to bits at the end of their lives.
The previous furthest-known supernova was nearly half as far away – six billion light-years.
The new supernovae – out towards the edge of the known universe – mark the deaths of two of the earliest stars created, say cosmologists.
They were spotted when an international team of astronomers stacked photos of the same area of sky, taken with a giant telescope on Hawaii, to enhance them. This allowed them to see fainter objects than usual – including the exploding stars.
Jeff Cooke, of California University, who led the search, said: “The universe is about 13.7 billion years old, so really we are seeing some of the first stars ever formed.”
He hopes the new technique will now allow astronomers to detect exploding stars even further away. The discoveries are revealed this week in the journal Nature.
Interestingly, a previous gamma ray burster was identified as the blast of an overweight star 13 billion years away.
