Largest-known exoplanet discovered
The exoplanet TrES-4
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Tuesday, 07, Aug 2007 02:00
Astronomers claim to have discovered the largest-known exoplanet in our universe.
Exoplanets – planets existing outside of our solar system – have been discovered by scientists studying stars looking for celestial bodies passing in front of them.
The new discovery, named TrES-4, is thought to be about 70 per cent bigger than Jupiter (the solar system's largest planet) but less massive, making it a planet with extremely low density.
"Its mean density is only about 0.2 grams per cubic centimetre, or about the density of balsa wood," said Georgi Mandushev, Lowell Observatory astronomer and the lead author of the paper announcing the discovery.
"And because of the planet's relatively weak pull on its upper atmosphere, some of the atmosphere probably escapes in a comet-like tail."
The planet lies about 1,400 light years away in the constellation of Hercules and orbits its host star in about three and a half days.
It is also extremely hot – about 1,600 Kelvin or 2,300F – due to its close proximity to the star.
"We continue to be surprised by how relatively large these giant planets can be," said Francis O'Donovan, a graduate student in astronomy at the California Institute of Technology who operates one of the trans-Atlantic exoplanet survey telescopes.
"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."