A Blast From the Past
A huge supernova raises questions about the early universe
Until recently, astronomers corralled all the stars in the universe into one of two retirement plans: out with a bang or out with a whimper.
Technically speaking, the massive supernova discovered by a University of Texas graduate student and made public last week falls into the first category-except that its "bang" was about 100 times bigger than any star explosion seen before. The burst was so spectacular, in fact, that it had astronomers re-evaluating the behavior of these enormous bodies and wondering whether they had been treated to a rare glimpse of the early universe.
"I think this supernova shows pretty clearly that our knowledge is incomplete," said J. Craig Wheeler, an astronomer at the University of Texas.
Hunting for supernovas is a tricky business. They are highly infrequent events, and telescope time isn't cheap. That's why astronomers like those wielding the 30-inch telescope at the Lick Observatory near San Jose, Calif., focus their searches in areas most likely to yield fruit: bright regions with all the right ingredients for star genesis. They also usually avoid the direct center of a galaxy, where other celestial flickering can be mistaken for a supernova, wasting valuable time. Given these practices, it came as no small surprise that astronomy student Robert Quimby made his discovery with an 18-inch telescope-puny by observatory standards.
Eye on the prize. "We decided we're not going to try to find the most supernovas," said Quimby. "We're going to try to find the best supernovas." So instead of confining his exploration to populous galaxies, he also looked elsewhere: in the middle of space, even directly into the eye of the galaxies. It was in the eye of a galaxy that he found his prize, "SN2006gy," 240 million light-years away.
At around 150 times the mass of the sun, SN2006gy is so big that it defies scientific understanding of how most stars live and die. The old models would suggest that SN2006gy should have imploded to become a black hole, but that does not appear to have happened. However rare today, these massive stars may have been common in the early universe, more than 10 billion years ago, scientists believe.
All stars spend most of their careers fusing helium out of pairs of hydrogen atoms-the same process of nuclear fusion used in H-bombs-but later they essentially become celestial bakeries, creating heavier elements in their cores and populating the universe with all the carbon and oxygen essential for life. Should this supernova prove to resemble its ancestors, it could offer valuable clues about how the universe unfolded to the point where human life was possible.
But there is another reason why Quimby's discovery is causing such a stir. In our own galaxy, another massive star, called Eta Carinae, is just a few astronomical blocks down the Milky Way, some 7,500 light-years away. Scientists report that Eta Carinae has exhibited many of the same properties as the star Quimby observed. Were it to blow-and it could, tomorrow or two millenniums from now-it would create a light so bright that the Southern Hemisphere would be cast into 24-7 daylight for months on end.
This story appears in the May 21, 2007 print edition of U.S. News & World Report.