Star Devours Its Own Planet

The star is squeezing a planet 40 percent larger than Jupiter into the shape of a football.

Wed Feb 24, 2010 11:47 AM ET | content provided by AFP

THE GIST:

One star 600 light-years away is essentially gobbling up one of its own planets.
So close is its orbit that the gravitational tug of the star has helped to squeeze one planet into a football shape.
Searing heat is stripping away layers of the gas, whose mass is then captured by the star.

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Like the Roman god Saturn who ate his own children, a star 600 light-years from Earth is slowly gobbling up one of its own planets, according to a study released on Wednesday in Nature, the British science journal.

The planet, whose discovery was reported last year, is a "gas giant" with a mass about 40 percent greater than that of Jupiter, the biggest planet of our Solar System, and with a radius 79 percent bigger.

But whereas Jupiter takes nearly 12 years to plod around the Sun, it takes WASP-12b a mere 26 hours to race around its star, WASP-12, located in the constellation of Auriga.

So close is its orbit that the gravitational tug of the star has helped to squeeze the planet into a prolate shape, meaning that it has taken the form of a rugby ball, or American football.

Searing heat is stripping away layers of the gas, whose mass is then captured by the star.

The disk of captured matter around the star may mask "a detectable resonant super-Earth," whose presence may cause WASP-12b to orbit in a remarkably egg-shaped path, suggests the study.

Most planets that orbit close to their sun have a more circular track.

The investigation is led by Shu-lin Li of the Department of Astronomy at the Peking University, Beijing.

More than 400 so-called exoplanets -- the term for planets that orbit stars other than the Sun -- have been spotted since 1995, although none has turned out to be a rocky, watery world like our own.

Most, like WASP-12b, are so-called "hot Jupiters," or huge gassy balls that are heated to scorching temperatures by proximity to their planets.

A planet with water would have to inhabit what has been termed the Goldilocks Zone, meaning that it is not so close that its precious water evaporates nor so far that the water freezes, but somewhere in between so that water can exist in liquid form.

From: http://news.discovery.com/space/star-gravitational-exoplanet.html