Swirling gases apparently reach 1,340 Fahrenheit
By JOSEPH B. VERRENGIA
A NASA telescope peering far beyond our solar system has for the first time directly measured light from two Jupiter-sized gas planets closely orbiting distant stars, adding crucial features to astronomy's portrait of faraway worlds. Studies of the infrared light from the two giant planets suggest they are made of hot, swirling gases that reach 1,340 degrees Fahrenheit or higher.
"It's an awesome experience to realize we are seeing the glow of distant worlds," said astronomer David Charbonneau of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., whose team captured light from a planet in the constellation Lyra. "The one thing they can't hide is their heat."
Since the mid-1990s, scientists have discovered more than 130 of these so-called extrasolar planets. But the stars they orbit are so distant and shine so brightly that they tend to overwhelm the planets from view. To find them, astronomers indirectly measure the tiny gravitational wobble that orbiting planets exert on their suns, or the brief dimming of starlight that occurs when a planet's orbit carries it in front of the star. But hot celestial objects like these gas planets also emit infrared light. NASA's Spitzer Space Telescope has detectors to collect these infrared signals.
One planet, HD 209458b, is nicknamed Osiris. It orbits a sun-like star in the constellation of Pegasus. Its infrared signature was measured by astronomers at the NASA Goddard Spaceflight Center in Greenbelt, Md. Details will appear today in the online version of the journal Nature. The other extrasolar planet measured by the Harvard-Smithsonian team is known as TRes-1. It is located in the constellation Lyra.
Results will be published in the June 20 issue of the Astrophysical Journal.