Sept. 8, 2006 —Astronomers using a tiny amateur-class telescope and off-the-shelf camera lenses have found a Jupiter-sized planet orbiting a star 500 light-years from Earth.
The planet, called TRES-2, is the first to be found in this particular field of view, known as the Kepler Field. And the discovery is the second for a network called the Trans-Atlantic Exoplanet Survey, or TrES, which taps small telescopes in California, Arizona and the Canary Islands to hunt for planets outside of our solar system.
The team looks for planets that pass in front of their parent stars, relative to the view from Earth. As the planets transit, they slightly dim the total amount of visible light that radiates from the star, as seen from Earth. By observing the star over a period of weeks or months, astronomers can detect if there are any objects that temporarily and regularly block a bit of sunlight.
"It's really difficult to make these measurements," said Francis O'Donovan, a graduate student at the California Institute of Technology and the lead author of a paper slated to appear in an upcoming issue of the Astrophysical Journal.
TrES-2 is a gas giant, similar to Jupiter but somewhat bigger and more massive. Unlike Jupiter, however, TrES-2 is very close to its parent star and very hot. The planet, discovered by O'Donovan and colleagues, dims its parent star's light by only 1.5 percent as it passes around every 2.5 days.
The astronomers also had to rule out other possible explanations for the dimming, such as a partner star gravitationally locked in orbit with the target star, which is called GSC 03549-02811 and is located in the constellation Draco.
Finally after months of work, the observation was confirmed by a large 10-meter telescope at the Keck Observatory in Hawaii.
"All our hard work was made worthwhile when we saw the results," O'Donovan said, who hopes to parlay his discovery into a doctorate degree in astronomy.
