Scientists report dramatic heating of 'eccentric' planet
Last Updated: Wednesday, January 28, 2009 | 1:22 PM ET
CBC News
U.S. scientists have made what they say are the first real-time observations of weather changes on a planet outside our solar system — an oddity that heats up several hundred degrees in a few hours.
"The giant planet orbiting the solar-type star HD80606 is unique among the nearly 300 extrasolar planets that have been found so far," the study says.
This uniqueness is due largely to what researchers call an "eccentric" 111-day orbit that brings the planet extremely close to the star for a period of just a few hours.
For most of its orbit, the planet circles its star at distances that would place it somewhere between Earth and Venus, relative to our sun. But at its closest, the planet is even closer to its star than Mercury is to the sun.
It also receives around 825 times more solar radiation than at its farthest point, the researchers say.
Astronomers used infrared sensors on NASA's Spitzer Space telescope to measure the temperature on the planet as it approached its star. They found that the planet heated up by 700 degrees in six hours, going from 525 C to 1,225 C as it moved closer.
Planet cools quickly
Almost as quickly, the planet moves away from its star and cools rapidly, the researchers say.
They were able to isolate the radiation given off by the planet when it moved behind the star, an occurrence known as a secondary eclipse. The researchers had not foreseen the eclipse, but said it was a stroke of good luck that allowed them to more accurately measure temperature shifts on the planet.
The researchers then analyzed the data from the telescope to gauge how temperature changes would affect the planet. As temperature rises, the researchers found their simulation showed large storms as wind picks up.
"Even after finding nearly 200 planets, the diversity and oddness of these new worlds continues to amaze and confound me," one of the study's authors, Paul Butler of the Carnegie Institution for Science, said in a release.
While the researchers can't get a direct image of the planet, they write in the study that "the planet itself can be used as a laboratory to study the atmospheric dynamics of extrasolar planets."
The planet — dubbed HD80606b — is about four times the mass of Jupiter and is 200 light years away from Earth.
Researchers from the University of California at Santa Cruz and the Carnegie Institution for Science made the observations on the planet. Their findings will be published in Thursday's edition of Nature.
