Astronomers find planet with thick, inhospitable atmosphere and icy heart

December 17th, 2009 - 1:33 pm ICT by ANI  

Washington, December 17 (ANI): A team of astronomers has discovered a new planet that has a thick and inhospitable atmosphere, with three quarters of its surface covered with water ice.

The newly discovered planet, named GJ1214b, has a mass about six times that of our terrestrial home and 2.7 times its radius, falling in size between the Earth and the ice giants of the Solar System, Uranus and Neptune.

It is the second time a transiting super-Earth has been detected, after the recent discovery of the planet Corot-7b.

Although the mass of GJ1214b is similar to that of Corot-7b, its radius is much larger, suggesting that the composition of the two planets must be quite different.

While Corot-7b probably has a rocky core and may be covered with lava, astronomers believe that three quarters of GJ1214b is composed of water ice, the rest being made of silicon and iron.

GJ1214b orbits its star once every 38 hours at a distance of only two million kilometres - 70 times closer to its star than the Earth is to the Sun.

“Being so close to its host star, the planet must have a surface temperature of about 200 degrees Celsius, too hot for water to be liquid,” said David Charbonneau, lead author of the paper reporting the discovery.

When the astronomers compared the measured radius of GJ1214b with theoretical models of planets, they found that the observed radius exceeds the models’ predictions.

There is something more than the planet’s solid surface blocking the star’s light - a surrounding atmosphere, 200 km thick.

“This atmosphere is much thicker than that of the Earth, so the high pressure and absence of light would rule out life as we know it, but these conditions are still very interesting, as they could allow for some complex chemistry to take place,” said Charbonneau.

“Because the planet is too hot to have kept an atmosphere for long, GJ1214b represents the first opportunity to study a newly formed atmosphere enshrouding a world orbiting another star,” said team member Xavier Bonfils.

“Because the planet is so close to us, it will be possible to study its atmosphere even with current facilities,” he added. (ANI)

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