Assassin Supernova

Close-up of star near a supermassive black hole (artist’s impression) Image credit: ESO, ESA/Hubble, M. Kornmesser When is a supernova not a supernova? The brightest supernova on record was discovered in 2015 by the All Sky Automated Survey for Supernovae (ASAS-SN). Named ASASSN-15lh, this remarkable event – what looked like a huge brightening of a star in a distant galaxy – was observed by many other telescopes, including the Hubble Space Telescope and the Las Cumbres Observatory network. With careful study, it became apparent that ASASSN-15lh was not quite what it seemed. Rather than being the explosion of a massive star, it is now thought that it was the final flash as a star was swallowed by a supermassive black hole. This month, Morgan Fraser, from University College Dublin, and Las Cumbres Observatory’s Edward Gomez explain the story of this discovery – and rediscovery! We finish with a brief recap of 2016, and a look forward to 2017. Originally broadcast on 19th December 2016 as part of Pythagoras’ Trousers on Radio Cardiff.