In comparison to most supernovae, which are only visible for a few months, the AT2021lwx explosion has already lasted for over three years, making it the largest ever witnessed.
The explosion took place nearly eight billion light years away, when the universe was around six billion years old, and is still being detected by a network of telescopes.
AT2021lwx was first detected in 2020 by the Zwicky Transient Facility in California and subsequently picked up by the Asteroid Terrestrial-impact Last Alert System (ATLAS) based in Hawaii. Until now, the scale of the explosion had been unknown.
“We came upon this by chance, as it was flagged by our search algorithm when we were searching for a type of supernova," said Dr Philip Wiseman, research fellow at the University of Southampton.
“Most supernovae and tidal disruption events only last for a couple of months before fading away. For something to be bright for two-plus years was immediately very unusual...