 |
|
Supernova may offer new view of early universe
The star's 'monster' explosion, observed last September, is the biggest ever seen.
from the May 8, 2007 edition
Page 2 of 3
Trying to avoid anything interesting
Typically, he conducts his own follow-up studies. But at the time his telescope captured the explosion last year, he was in the midst of writing his PhD thesis. "I was actively trying not to find anything interesting to distract me," he recalls. When the image popped up, "I said, 'Yeah, it's a supernova. I'll just tell other people about it' " and let them do the follow-up work.
Enter Nathan Smith and colleagues from the University of California at Berkeley. The team suspected this was no ordinary supernova. Its brightness was one tip-off. So was its longevity. Usually, a supernova's light – which briefly outshines its galaxy – peaks and then fades over several weeks back into a galaxy's background light.
"This one rose for something like 70 days toward its peak and then stayed there, or declined only slightly, for several months," explains Alexei Filippenko, a Berkeley astronomer and member of the research team, which includes Quimby and Craig Wheeler of the University of Texas. Their work has been submitted for publication to The Astrophysical Journal.
The team has lost sight of the supernova because its host galaxy now lines up too close to the sun to observe. "But the last time we saw it, it was still really, really bright," Dr. Filippenko says.
Add up all the energy needed to sustain that brightness for so long, he continues, and it works out to be 100 times more powerful than a normal supernova. "This was a truly monstrous explosion," adds Dr. Smith. "We've never seen that before."
Some researchers have suggested that the blast is a normal supernova whose progenitor star lived in a hydrogen-rich neighborhood. The long-lived light would result as the copious number of atoms ejected by the blast collided with the hydrogen. But that would result in large X-ray emissions. So astronomers aimed NASA's Chandra X-ray Observatory at the supernova and found that its X-ray emissions were far too faint to match that explanation.
Others suggested that the bright event might be a supermassive black hole at the galaxy's center acting up. But the supernova falls just outside the galaxy's core.
This leaves the door open to an exotic form of supernova that theorists invoke to explain the end times for many of the universe's earliest stars.
Typically, a star at least 10 times more massive as the sun burns off the heavier chemical elements it creates in its fusion furnace. When the only fuel left is iron, burning stops. The outward "push" of the star's radiation against the orb's gravity vanishes. The star collapses, squeezing the iron core until it rebounds and blasts away the remaining outer material. What's left is a dense, spinning ball known as a neutron star, or in some cases, a black hole.
RSS feed
