Mysterious Cosmic Blast Keeps on Going By Ron Cowen, Science News Email Author April 8, 2011

Astronomers have witnessed a cosmic explosion so strange they don’t even know what to call it. Although the blowup, discovered with NASA’s Swift satellite on March 28, emits high-energy radiation like a gamma-ray burst would, the event has now lasted for 11 days. Gamma-ray bursts last for an average of about 30 seconds.

Also unlike a gamma-ray burst, the explosion has faded and brightened, emitting staccato pulses of energetic radiation lasting for hundreds of seconds.

“It’s either a phenomenon we’ve never seen before or a familiar event that we’ve never viewed in this way before,” says Andrew Fruchter of the Space Telescope Science Institute in Baltimore. The outburst might have been generated by a star torn to shreds when it ventured too close to a black hole in its host galaxy, he suggests. Gas from the star falling into the black hole could have triggered the gravitational monster to emit a jet of X-rays and gamma rays that by chance happens to point directly at Earth.