A star in a galaxy not so far way, at least in cosmic terms, is exploding, astronomers say. Already the star outshines its entire galaxy, a smudge of light about 440 million light-years away in the constellation Aries. But that, astronomers believe, is still only the beginning, and telescopes around the world are being turned toward Aries in anticipation of documenting one of the rarest and most violent events in nature, a supernova explosion.

The conflagration was detected on Saturday as a long burst of gamma rays by NASA's Swift satellite. Such bursts have been linked to supernova explosions in which a massive star collapses into a black hole.

This burst, however, is an oddball. It lasted nearly 2,000 seconds, or about half an hour, 100 times longer than a typical burst, and was much weaker, said John Nousek, a Pennsylvania State astronomer and the director of the Swift mission.

"It's so early we don't have a clear answer to what it is," Dr. Nousek said yesterday. "What is clear is that it is nearby and associated with supernova."

Nobody will need sunglasses. At maximum light, Dr. Nousek said, the exploding star would probably be about twice as bright as it is now, within reach of professional and large amateur telescopes, but not the unaided eye. Usually the bursts are so far away across the cosmos that the visual light from the actual explosions is never seen, but this one, called GRB 060218, after the date on which it was discovered, is the second closest ever found, practically next door, leaving astronomers with their armada of instruments in an enviable position.

Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics, who called the event "a lot of fun," said, "We have a lot to learn about these super-duper explosions, and it is great to have an agile satellite like Swift working so beautifully."

# posted by myopic astronomer : 9:35 AM