The Brightest Supernovae Of All Have A Suspiciously Common Explanation
“Either way, this represents a new step forward towards understanding the most energetic stellar cataclysms in the Universe: superluminous supernovae. Even though hydrogen was present in narrow lines, leading to an initial classification as a type IIn supernova, the full suite of data is better fit by a white dwarf core merging with a giant or supergiant's core, with the supernova's ejecta crashing into a large amount of circumstellar material that had been previously ejected.
While there's a whole lot we've learned from SN 2006gy, the closest superluminous supernova, many others have been seen with similarities, but none were close enough to detect iron lines so long after the initial explosion took place. Is a white dwarf merging with a giant or supergiant core the way all superluminous supernovae are created? Or is SN 2006gy rare, or do we perhaps even have it wrong after all? Whatever the case, we're one step closer to understanding what causes the most energetic stellar cataclysms ever seen in the Universe.”
In 2006, an explosion unlike any other was seen. A supernova went off in a galaxy some 238 million light-years away: in and of itself not such a big deal. But unlike previous supernovae, this one was about 100 times more energetic than normal: a superluminous supernova. More than a year after it was observed, so much light was still coming from it that astronomers were able to take a spectrum of it, and found emission line features that they’d never seen before. While most scientists assumed this was due to the core collapse of an ultra-massive star, a new analysis showed something different and unexpected: despite having hydrogen present, this matches the light-curve of a white dwarf-driven supernova, not a pair-instability supernova.
How are the most luminous, brightest stellar cataclysms in the Universe formed? After this analysis, we might have to rethink everything.