Largest known extrasolar planet discovered

An international team of astronomers with the Trans-Atlantic Exoplanet Survey has discovered a new estrasolar planet, 1400 light years away, in the constellation of Hercules.

Washington, Aug 7 : An international team of astronomers with the Trans-Atlantic Exoplanet Survey has discovered a new estrasolar planet, 1400 light years away, in the constellation of Hercules.

The team identified the planet while looking for transiting planets using a network of small, automated telescopes in Arizona, California, and the Canary Islands. Transiting planets are those that pass in front of their home star.

The planet TrES-4 was discovered less than half a degree (about the size of the full Moon) from the team's third planet, TrES-3.

"TrES-4 is the largest known exoplanet," said Georgi Mandushev, Lowell Observatory astronomer and the lead author of the paper announcing the discovery.

"It is about 70 percent bigger than Jupiter, the Solar System's largest planet, but less massive, making it a planet of extremely low density. Its mean density is only about 0.2 grams per cubic centimetre, or about the density of balsa wood! And because of the planet's relatively weak pull on its upper atmosphere, some of the atmosphere probably escapes in a comet-like tail," Mandushev said.

The Lowell Observatory's Planet Search Survey Telescope (PSST) first discovered the new planet. The PSST was set up and is operated by Edward Dunham and Georgi Mandushev.

The observatory also observed transits of TrES-4, confirming the initial detections.

TrES-4 orbits its host star in three and a half days. Being only about 4.5 million miles from its home star, the planet is also very hot, about 1,600 Kelvin or 2,300 degrees Fahrenheit.

"TrES-4 appears to be something of a theoretical problem. It is larger relative to its mass than current models of superheated giant planets can presently explain," said Edward Dunham, Lowell Observatory Instrument Scientist.

"We continue to be surprised by how relatively large these giant planets can be. But if we can explain the sizes of these bloated planets in their harsh environments, it may help us understand better our own Solar System planets and their formation," added Francis O'Donovan, a graduate student in astronomy at the California Institute of Technology who operates one of the TrES telescopes. "

The study "TrES-4: A Transiting Hot Jupiter of Very Low Density" is scheduled for publication in the Astrophysical Journal.

ANI