Hypernova and Gamma Ray Bursts
Nova last night was on Hypernovae (the web site is here but is only so so). A hypernova is a supernova for a specific type of star (a "Wolf-Rayet") that is very hot and massive. When it dies, the core of the star doesn't just burn but collapses in on itself creating a blackhole at the center of the star. In a matter of minutes the black hole absorbes the rest of the star. From here is gets really wierd - the black hole has to conserve the angular momentum of the star but can only spin so fast so it must emit a set of gamma ray jets to get rid of some of the angular momentum (it's not really clear why the energy is emitted in this way). The gamma ray burst produced lasts from seconds to an hour and can be observed on earth. Gamma rays have been observed for a long time but only recently has their production been tied to the death of stars.