SPACE.com: All supernova explosions are violent affairs, but astronomers have spotted a new type of extremely bright cosmic explosion they think originates from an exceptionally massive star.This breed of explosion has been long predicted, but never before seen. Like all supernovas, the blast is thought to have marked the end of a star’s life. But in this case, that star may have started out with 200 times the mass of the Sun.The supernova in question, SN2007bi, was observed in 2007 in a nearby dwarf galaxy. Scientists knew at once it was something different because it was about 50 to 100 times brighter than a typical supernova.After analyzing its signature, astronomers published a paper in Nature confirming that it matches theoretical predictions of a so-called pair-instability supernova.