Doomed Planet

StarDate: February 24, 2009

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The end is near for a planet that orbits a giant star near the tail of Leo, the lion. The star is nearing the end of its own life, so it's puffed up to giant proportions. And that means bad news for the planet.

The star is known by a catalog number, HD 102272. It's a red giant -- a star that's undergoing dramatic changes as it nears the end of its life. Its core is getting smaller and hotter, while its outer layers expand and cool. The star is already 10 times wider than the Sun, and it's still growing.

Last year, a team of astronomers using the Hobby-Eberly Telescope at McDonald Observatory discovered a planet orbiting the star, along with hints of a second planet.

The confirmed planet is about six times as massive as Jupiter, the largest planet of our own solar system. But it's only about half as far from the star's surface as Earth is from the Sun. That's closer than any other planet yet discovered orbiting a red-giant star.

And in fact, this planet may not last long. Although it's probably a big ball of gas, like Jupiter is, intense heat from the star is probably evaporating the planet's outer atmosphere. Radiation and strong "winds" of charged particles blow the atmosphere away.

The wind may also slow the planet down, causing it to spiral closer. Eventually, that could seal the planet's doom -- as it falls into the expanding star.

Script by Damond Benningfield, Copyright 2008

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