Supenova Bursts with Opportunity for Astronomers

2/25/06 Denver Post

(Comments added in italics 3/8/06)


A supernova has astronomers around the globe racing to their telescopes. The advent of the exploding star was heralded by a burst of gamma-ray radiation, detected Feb.18, 2006 by NASA's Swift satellite. Three days later, scientists matched the burst to the birth of a supernova. The gamma ray burst was the second closest to Earth ever detected scientists say. The supernova is 440 million light years away in the direction of the constellation Aries.

Astronomer Daniele Fargion of Italy's Rome University calls the blast "puzzling" in an announcement of the discovery because it lasted about 33 minutes. Earlier supernovas have lasted for about 10 seconds, but this one also seems comparatively weak, Fargion says, in terms of the intensity of its gamma ray bursts. As discussed earlier, if the power production mechanism is fission, then a series of criticalities can take place that are fostered by core collapse balanced against burnup of available fuel. The speed of collapse and the amount of fuel available can affect the time scale and magnitude of the energy release, with slow collapse lengthening the time and decreasing the output.

Using large telescopes tuned to different parts of the electromagnetic spectrum, scientists should be able to discover the chemistry of an exploding star for the first time, from within 100, seconds of the blast's beginning to its end. So far, the blast seems to herald a Type 1C supernova, says Fargion. That occurs when a star has consumed all its nuclear fuel, leaving behind only an iron core, which then implodes.

Gamma rays smoothly ramped up in the half-hour blast, a departure from the usual pattern of short, sharp peaks. That may indicate that the axis of the supernova, which typically produces jets of exploding material, was pointed away from Earth. A repetitive pattern of peaks is a characteristic of a self-controlled fission process!