UT astronomers confirm new planet discovery
Posted on 10/09/2002 5:00:00 AM PDT by MeekOneGOP
UT astronomers confirm new planet discovery
10/09/2002
University of Texas astronomers have confirmed that a planet orbits one of a pair of stars 45 light-years (260 trillion miles) away. It is the first discovery of an "extrasolar" planet in a binary star system where the two stars orbit each other closely.
Such binary systems are common in the galaxy.
"When you look at the stars in the sky, every other one of them is a double star or multiple star" says Canadian astronomer Gordon Walker. Planets have been found in binary star systems before, but in those cases the two stars were separated by a distance at least 100 times greater than in this case.
If a planet can form in a close binary system, without getting tossed out of orbit by the secondary star, then extrasolar planets might be more common in the universe than previously believed, Dr. Walker says.
William Cochran of UT-Austin, who led the research team, planned to describe the planet Wednesday in Birmingham, Ala., at a meeting of the Division for Planetary Sciences of the American Astronomical Society. Team member Artie Hatzes announced the discovery last month at a scientific meeting in Germany.
The star in question is known as Gamma Cephei, or Errai, which is the third-brightest star in the constellation Cepheus the King. Gamma Cephei has a dim companion star that orbits from 1 billion to 3 billion miles away; at most, that places the two stars as far apart as the sun and Neptune.
The newfound planet orbits Gamma Cephei at an average distance of 200 million miles, or about twice the distance between the sun and the Earth. The planet is nearly twice as massive as Jupiter and takes about 2 1/2 years to go around its star.
Gamma Cephei is the brightest star other than the sun known to have a planet, Dr. Cochran says.
"Even in Dallas you can see it," he says.
Cepheus is currently visible high in the north-northeast around 8 p.m.; Gamma Cephei is the bright star at the top of the king's "hat."
The star is about 3 billion years old, a bit younger than the 4.6-billion-year-old sun. But Gamma Cephei is more massive than the sun, so it will burn through its nuclear fuel sooner and die.
Astronomers don't know whether the planet might have formed around Gamma Cephei, as the Earth did around the sun, or whether it might have been captured from elsewhere in space. But its near-circular orbit suggests that it may have formed in place, Dr. Walker says.
And that could mean Gamma Cephei's planet would be a good place to search for extraterrestrial life. It could be at the right distance for water - considered a prerequisite for life - to exist without boiling away or freezing. Although the planet itself is probably a gas giant like Jupiter, it could have rocky moons that could support life, says Dr. Cochran.
Astronomers had suspected before that Gamma Cephei might have a planet. In 1988 Dr. Walker, who is now retired from the University of British Columbia, published a paper suggesting just that.
But at the time, planet-hunting techniques were more primitive than they are today, he says. His team couldn't be sure they weren't just seeing ripples in the gas of the star's surface. In 1992, the scientists retracted their claim.
Three years later, other astronomers announced evidence for the first planet around a sunlike star (51 Pegasi, in the constellation Pegasus), opening up a floodgate of discoveries.
"The burden of proof on the first planet was much greater than that on the 101st, which is what we're at now," Dr. Cochran says.
His team combined observations from McDonald Observatory in West Texas with those taken by Dr. Walker on the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. Together, the observations spanned more than 20 years - long enough to rule out the possibility that the signal was caused by fluctuations on the star's surface.
"I'm just delighted that they've gone ahead and put this together," says Dr. Walker. "I always kicked myself a little bit that we probably should have looked even harder. … But there was a climate of skepticism at the time."
In 2000, Dr. Cochran's team confirmed a planet circling the star Epsilon Eridani, which also had been suggested by Dr. Walker's group.
Both teams looked for the presence of planets by scrutinizing the movement of stars. The presence of a nearby planet exerts a gravitational tug on a star, which astronomers can measure as a tiny shift in the color of light coming from the star. The amount of the shift tells them how massive the planet is and how far it orbits from its star.
For more information about the planet, visit cfa-www.harvard.edu/planets/. For an interactive sky chart, visit skyandtelescope.com/observing/.
E-mail awitze@dallasnews.com
If a planet can form in a close binary system, without getting tossed out of orbit by the secondary star, then extrasolar planets might be more common in the universe than previously believed, Dr. Walker says.
Hmm? This increases the chances for Intelligent life out there somewhere?
Perhaps they'll come visit us and convert the Liberals to Conservatives.
It is the first discovery of an "extrasolar" planet in a binary star system where the two stars orbit each other closely.I've suspected for months that binary star systems could be orbited by planets.
I think you've gotten confused about his boss searching for a different planet...
LOL! Okay, how 'bout today?.....
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