In early 2008, a star briefly flared to life in the constellation Ophiuchus. It shined brightly enough to see with the unaided eye for a few seconds, then vanished. That may not sound very impressive until you consider this: The star was seven and a half billion light-years away — thousands of times farther than any other object that’s visible to the human eye. Yet it was even brighter in a form of energy we can’t see: gamma rays. For a few minutes, this gamma-ray burst was the brightest object in the universe. In that short span, it radiated more energy into space than the Sun will produce in its entire 10-billion-year lifetime. This brilliant burst probably announced the death of a supermassive star. The star could no longer produce nuclear reactions in its core. Without the radiation from those reactions to push against the pull of gravity, the core collapsed, perhaps forming a black hole. In this scenario, some of the gas around the core formed a superhot disk. Energy from the disk
