Sunday, September 17, 2006

Beyond Sol. EXO Planets

Art Image
of early Earth
Ocean, Moon

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Astronomers Reveal first Exo Planet ID chart
Boston MA (SPX) Sep 14, 2006

It is only a matter of time before astronomers find an Earth-sized planet orbiting a distant star. When they do, the first questions people will ask are: Is it habitable? And even more importantly, is there life present on it already? For clues to the answers, scientists are looking to their home planet, Earth.
Astronomers Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics (CfA) and Wesley Traub of NASA's Jet Propulsion Laboratory and CfA, propose using Earth's atmospheric history to understand other planets. "Good planets are hard to find," said Kaltenegger. "Our work provides the signposts astronomers will look for when examining truly Earth-like worlds."
Read More ... Harvard-Smithsonian CfA edu press

New Planet
Baffles Astronomers

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by Staff Writers
Boston MA (SPX) Sep 14, 2006

Using a network of small, automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta.
"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at CfA. Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery

With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter.

"This planet is about one-quarter the density of water," Bakos said. "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher."

HAT-P-1's parent star is one member of a double-star system called ADS 16402 and is visible in binoculars. The two stars are separated by about 1500 times the Earth-Sun distance. The stars are similar to the Sun but slightly younger - about 3.6 billion years old compared to the Sun's age of 4.5 billion years.

Although stranger than any other extrasolar planet found so far, HAT-P-1 is not alone in its low-density status. The first planet ever found to transit its star, HD 209458b, also is puffed up about 20 percent larger than predicted by theory. HAT-P-1 is 24 percent larger than expected.

"Out of eleven known transiting planets, now not one but two are substantially bigger and lower in density than theory predicts," said co-author Robert Noyes (CfA). "We can't dismiss HD209458b as a fluke. This new discovery suggests something could be missing in our theories of how planets form."

Related Links:
Harvard-Smithsonian Center for Astrophysics

Changing World View philosophical-juggernaut by Plato
Spherical Earth ??? sphere-that-is-not-so-round by Plato

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