Perry Vlahos -Feb 23, 2012
Chandra X-ray & Hubble Optical Composite of Supernova 1987A Supernova 1987A occurred in the Large Magellanic Cloud, a galaxy only 160,000 light years from Earth. The outburst was visible to the naked eye, and is the brightest known supernova in almost 400 years. Optical hot-spots (pink-white) now encircle the ring like a necklace of incandescent diamonds. The Chandra data (blue-purple) reveals multimillion-degree gas at the location of the optical hot-spots.
ALONG time ago in a galaxy far away - in fact, 160,000 years ago and the same number in light years - a blue supergiant star was reaching a critical stage.
An inevitable change was about to occur, though it would take 160,000 years before the news reached Earth. Such a catastrophic event is a rare phenomenon that might happen, on average, once every century in each galaxy. When a star's number comes up, it gets the attention of everybody.
Supernovas will do that because they are the most violent acts in the universe.
The explosion of this particular star was exquisitely timed, for had it happened even a century earlier, we would have been ill-prepared to study it with the same thoroughness. We became aware of the event, now referred to as Supernova 1987A, on this day 25 years ago - February 23, 1987. Three independent observers each noticed a star not there the night before in the Large Magellanic Cloud (LMC) - a satellite galaxy of the Milky Way. It was the first supernova visible with the naked eye since 1604.
A supernova explosion is the final stage in the life of a supergiant star. In short, when the star runs out of fuel to burn at its core and is not able to radiate further, gravity takes over and always wins the battle. It triggers a sudden implosion, followed by a rebounding explosion that tears the star apart, giving us celestial fireworks unmatched by any other cosmic event. For a brief period, the supernova outshines the combined light of all stars in its host galaxy.
Supernova 1987A was an unusual case as the progenitor star was not a red supergiant, as is the norm. Studies have indicated the star was originally a red supergiant but because of the special conditions in the LMC, it had relatively recently turned into a blue supergiant.
Unfortunately, it would be three years after the explosion before the Hubble telescope would be in space, so it missed the crucial early fireworks. But when it was ready and able to look at Supernova 1987A, it showed us an intriguing set of rings around the nucleus of the explosion, the origins of which we are still trying to fully comprehend.