Astronomers reveal secrets of most distant supernova ever detected

Supernovae are already some of the brightest explosions in the universe - but there's a more mysterious type, called superluminous supernovae, that can shine a hundred times brighter than the usual ones. And on 22 August 2016, astronomers spotted one whose light travelled over 10 billion years to reach us.

                                Image: Mat Smith, University of Southampton

The University of Southampton led by an international team of astronomers has confirmed the discovery of the most distant supernova ever detected -- a huge cosmic explosion that took place 10.5 billion years ago, or three-quarters the age of the Universe itself.

A supernova is the explosion of a massive star at the end of its life cycle. The exploding star, named DES16C2nm, was detected by the Dark Energy Survey (DES), an international collaboration to map several hundred million galaxies in order to find out more about dark energy - the mysterious force believed to be causing the accelerated expansion of the universe.

This object is important not only on its own, but for the future of astronomy. These superluminous supernovae seem to be more common the further away scientists look, according to the paper published recently in The Astrophysical Journal. In that case, it's important that researchers learn what they can about the distant events now. Upcoming telescopes such as the Large Synoptic Survey Telescope, Euclid and the not-dead-yet Wide-field Infrared Survey Telescope might be able to spot a lot more of them.

"It is thrilling to be part of the survey that has discovered the oldest known supernova. DES16C2nm is extremely distant, extremely bright, and extremely rare - not the sort of thing you stumble across every day as an astronomer," said lead author of the study Mathew Smith, of the University of Southampton in the UK. "As well as being a very exciting discovery in its own right, the extreme distance of DES16C2nm gives us a unique insight into the nature of SLSN.

"The ultraviolet light from SLSN informs us of the amount of metal produced in the explosion and the temperature of the explosion itself, both of which are key to understanding what causes and drives these cosmic explosions," said Smith. "Finding more distant events, to determine the variety and sheer number of these events, is the next step," said Professor Mark Sullivan, also of the University of Southampton.

This is the most distant supernova that's been spectroscopically confirmed - that is, whose light spectrum has been analysed to confirm its identity. But it isn't the most distant candidate. Researchers spotted two others back in 2012 and were able to measure the lights' distances (both further than this one), but did not confirm the identities spectroscopically.

The universe's 13.8-billion-year past is simply written in the sky, waiting to be uncovered by our high-tech optics. DES16C2nm may be the furthest confirmed supernova yet, but there's no doubt that a ton more await discovery.