Word: supernova
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
Schmidt's group and a rival team led by Saul Perlmutter, of Lawrence Berkeley Laboratory in California, used very similar techniques to make the measurements. They looked for a kind of explosion called a Type Ia supernova, occurring when an aging star destroys itself in a gigantic thermonuclear blast. Type Ia's are so bright that they can be seen all the way across the universe and are uniform enough to have their distance from Earth accurately calculated...
...rather, nobody had got enough data. Back in 1997, astronomers Mark Phillips of the Space Telescope Science Institute and Ron Gilliland of the Carnegie Institute of Washington had used the Hubble Space Telescope to spot a distant supernova designated SN 1997ff and, with the help of Peter Nugent, a Lawrence Berkeley astronomer on Perlmutter's team, had determined its speed of recession from Earth. Nugent couldn't figure out the distance, though: determining the brightness of a Type Ia calls for not just one but several measurements, spread over time...
...rival team, Riess knew of the discovery, but he learned soon afterward that other Hubble photos had also caught the supernova, completely by chance. So one day last summer, he recalls, "I called Peter and began fishing around for information. I guess I wasn't especially cagey. He said almost right away, 'Are you asking about 1997ff...
...existence is becoming hard to dispute. The first hint came a couple of years ago, when two independent teams of astronomers tried to calibrate the cosmic expansion using Type Ia supernovas, a kind of exploding star whose intrinsic brightness is highly consistent. Comparing the known brightness of such a supernova with how bright it appears in the sky gives a good measure of how far away it is--and thus how long ago in cosmic history its light was emitted. Then, by measuring how fast each supernova is moving away from Earth in the overall ballooning of the universe...
Critics argued that there might be a more conventional explanation, such as intergalactic dust, which could contaminate the brightness measurements. But the new observations seem to have closed that loophole. The newly identified supernova went off about 11 billion years ago--about 50% further back in time than the previous record holder. "If the dust were there," says Lawrence Berkeley astrophysicist Peter Nugent, a member of Perlmutter's team and Riess's collaborator on the new research, "the supernova would have been much dimmer than...