A rchive Date
[ 07-08-2000 ]
Category
[ Science ]
sub-Categoy
[ Astronomy ]
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[Scientists find nine new planets
Discovery brings total to 50 known outside solar system
By JILL LAWLESS- The Associated Press
Monday, August 7, 2000
LONDON (AP) - Astronomers said Monday they have found nine new planets circling stars outside our solar system - evidence that the Earth and its neighbours may not be as special as we like to think.
Three teams of researchers from Switzerland and the United States told a meeting of the International Astronomical Union about the discovery of the so-called 'exoplanets,' including one known to be the second planet orbiting a single star. It was only the second time astronomers have found more than one planet orbiting a star outside our own solar system.
"The findings suggest that it's quite common to have planets around other stars, so our solar system is not as unique as we might think," said Jim O'Donnell, a spokesman for the astronomical group. "That makes the possibility of life in the universe more likely."
A team from Switzerland's Geneva Observatory told the meeting in the northern English city of Manchester about the discovery of six new planets.
Scientists from the University of California at Berkeley said they discovered three exoplanets - including one also discovered by the Swiss group.
Additionally, astronomers based at the University of Texas at Austin's McDonald Observatory announced that they had found a Jupiter-sized planet orbiting the star Epsilon Eridani, 10.5 light years from Earth, bringing the total to nine.
The Berkeley team also found evidence suggesting that five stars known to have one orbiting planet may in fact be orbited by more - an indication that multi-planet systems such as our own may be common.
"This is the first time anyone has noticed that such a high percentage of stars with one known planet show evidence of a second companion," said Deborah A. Fischer, a postdoctoral fellow at Berkeley.
The discovery of a new planet so close to Earth, and circling a star similar in size to our sun, is "like finding a planet in our own backyard," said University of Texas astronomer Dr. William D. Cochran.
Scientists have now found 50 exoplanets, 41 of them in the last five years. Increasingly sensitive equipment capable of detecting how a circling planet can make a star wobble has produced the spate of new discoveries.
"We're now at a stage where we are finding planets faster than we can investigate them and write up the results," said Berkeley team leader Geoffrey Marcy.
"It's wonderful. Planet-hunting has morphed from the marvelous to the mundane," Marcy said.
Nonetheless, many mysteries remain. Current equipment can only sense the wobble caused by a big planet, so an Earth-sized planet - more likely to have an atmosphere capable of sustaining life - could not be detected.
And while scientists can estimate the mass of the newly discovered planets, they cannot look at them. They are so far away that they cannot be seen with the most powerful existing telescopes.
"You can't see them directly, because they reflect so little light," said O'Donnell. "However, astronomers are talking about larger telescopes in the next five to 10 years that could possibly see them."]
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