Gamma ray burst formation. Image 3 of 5. Computer artwork of the core of a massive star just after the inner core (centre) collapsed to form a black hole in a gamma ray burst (GRB) event. Surrounding shells of material, formed as the nuclear fusion that prevented collapse failed, are being drawn in by the black hole's intense gravity. Such core collapses are used to explain GRBs. This collapsar theory says the magnetic field of the black hole, or its spin, forms ejected material into jets. The jets are the source of the gamma rays of the GRB, a massive short-lived burst of energy that is 100s of times brighter than an ordinary supernova. For GRB formation, see images R670/148-152.