Monday, May 26, 2008
Scientists witness start of star’s explosive death
In a stroke of cosmic luck, astronomers for the first time witnessed the start of one of the universe’s most fiery events: the end of a star’s life as it exploded into a supernova.
On Jan 9, astronomers used a NASA X-ray satellite to spy on a star already well into its death throes, when another star in the same galaxy started to explode. The outburst was 100 billion times brighter than Earth’s sun. The scientists were able to get several ground-based telescopes to join in the early viewing and the first results were published in Thursday’s issue of the journal Nature.
“It’s like winning the astronomy lottery,” said lead author Alicia Soderberg, an astrophysics researcher at Princeton University. “We caught the whole thing from start-to-finish on tape.” Another scientistcalled it a “very special moment because this is the birth, in a sense, of the death of a star.” And what a death blast it is.:damned: “As much energy is released in one second by the death of a star as by all of the other stars you can see in the visible universe,” Filippenko said.
Less than 1 percent of the stars in the universe will die this way, in a supernova, said Filippenko, who has written a separate paper awaiting publication. Most stars, including our sun, will get stronger and then slowly fade into white dwarfs, what Filippenko likes to call “retired stars,” which produce little energy.
The first explosion of this supernova can only be seen in the X-ray wave length. It was spotted by NASA’s Swift satellite, which looks at X-rays, and happened to be focused on the right region, Soderberg said. The blast was so bright it flooded the satellite’s instrument, giving it a picture akin to “pointing your digital camera at the sun,” she said.
[B]The chances of two simultaneous supernovae explosions so close to each other is maybe 1 in 10,000, Soderberg said. The odds of looking at them at the right time with the right telescope are, well, astronomical. Add to that the serendipity of the Berkeley team viewing the same region with an optical light telescope. It took pictures of the star about three hours before it exploded.[/B]
This new glimpse of a supernova seems to confirm decades-old theories on how stars explode and die, not providing many surprises, scientists said. ap
http://www.dailytimes.com.pk/default.asp?page=2008%5C05%5C26%5Cstory_26-5-2008_pg6_1
