An alien planet France’s Corot space telescope recently discovered orbiting another star has the potential to host water in its atmosphere, scientists say.
The suspected temperate nature of the planet — whose surface temperature is between minus-20 degrees and 160 degrees Celsius — could mean that it could harbor liquid water. But this water would not be in the form of Earth-like oceans; more likely it would be only in the form of clouds with water droplets, said Tristan Guillot, a member of the team that discovered the planet.
Astronomers announced the discovery of the planet, dubbed Corot-9b, March 17 when they described it as a Jupiter-size world that orbits its parent star at about the orbit of Mercury in our solar system. This distance, while it seems close to the star, is considerably farther out than many other known Jupiter-size exoplanets, which means that Corot-9b likely escapes the wild temperature extremes experienced by those planets.
“The same is true for Jupiter, which actually has water clouds, but they’re hidden from view in the deep atmosphere,” Guillot wrote in an e-mail.
Water oceans are out of the question because gas giant planets “don’t have any surface: One goes continuously from the atmosphere to a progressively denser environment in the interior,” Guillot said.
Guillot said the interior of the planet could include a core made of water compressed to extremely high pressures and temperatures. Under such conditions, he said, the water probably would become an ionized plasma and behave a bit like liquid water. “But calling it an ocean would be far-stretched,” he said.
Another possibility for water in this new planetary system would be the presence of a moon.
If the temperatures at Corot-9b’s orbit are in the right range, an ice-ball moon could exist, like Saturn’s moon Titan, or possibly even a moon with liquid oceans.
“Titan-like moons with dense atmospheres and liquid water on the surface may exist there,” said Hans Deeg, another member of the team that discovered the planet.