Researchers Photograph New Planet
Thursday, November 13, 2008
Category: News > University > Research and Ideas
Not very long ago, in a planetary system 25 light years away, UC Berkeley researchers took the first-ever photograph of what is believed to be a planet orbiting a star in a solar system other than our own.
The image was published in the online version of Science yesterday, following nearly a decade of research. The effort was led by Paul Kalas, a UC Berkeley assistant adjunct professor of astronomy and the study's principle investigator, who took the photograph using the Hubble Space Telescope.
Kalas said it was the first time researchers had directly imaged the motion of a planet around a star, making the photograph "absolutely amazing."
"When you see this planet moving along in orbit, it's almost as if it comes alive," Kalas said. "It's extremely satisfying, because in comparison to all the other studies of exoplanets, no one else had predicted the location of a planet through theory."
The hunt for the planet began when researchers were studying the dust belt of a nearby star, called Fomalhaut, in 2005. Eugene Chiang, an associate professor of astronomy and earth and planetary sciences who helped design models for the project, was one of the first to postulate the planet's existence.
"(The belt) had a peculiar eccentric shape and a sharp inner edge, both of which are clues that a planet is present," Chiang said.
He told his suspicions to Kalas, who said he was busy working on a discovery of historic importance. Then, in May, Kalas revealed his image to Chiang.
"And then I had to sit down, because I was just stunned," Chiang said.
The planet, which by Chiang's calculations could be no more than three times the mass of Jupiter, was exceptionally bright for its size.
"It's totally unprecedented, so we're having to stretch our imaginations as to why these planets are so bright in the optical and so faint in the infrared," Chiang said.
The planet's unusual luminescence might be due to a system of rings-perhaps 20 times as large as those of Saturn-reflecting light into the telescope. But despite its brightness, he said, the planet is the least luminous object ever photographed outside our solar system.
James Graham, a UC Berkeley professor of astronomy and co-author of the study, was also struck by the photograph.
"The first time you saw this thing was just a feeling of awe and delight and wonder," Graham said. "It's really all these strong emotional feelings that make you want to work on things like this till 3 o'clock in the morning."
Graham said researchers confirmed that the object was a planet by measuring its orbital rate, which turned out to be the expected rate for a planet 120 astronomical units from a star. Combined with its size and the shape of the dust belt, this established that the object was a planet and not a small star.
The next step, Kalas said, is to find out from what the planet is made. Researchers will use as many tools and telescopes as possible, including the Very Large Telescope in Chile and the spectrograph aboard the Hubble telescope, to probe the planet's atmosphere and composition.
By next summer, they hope to have a spectrum of the planet, Kalas said.
Although the discovery of a planet outside our solar system was not unexpected by those in the field, it is still significant for astronomy, said Mike Brown, the professor of planetary astronomy at the California Institute of Technology who "killed" Pluto.
"It's like you're sailing across the sea," Brown said. "You know you're going to reach shore, but when you finally see it, it's still an exciting moment."
Rachel Gross covers research and ideas. Contact her at [email protected]
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