Planet Gliese 581 g pulls a vanishing act

Last month, a team of astronomers announced the discovery of the first alien world that could host life on its surface. Now a second team can find no evidence of the planet, casting doubt on its existence.

The planet, dubbed Gliese 581 g, was found to orbit a dim, red dwarf star every 37 days, according to an analysis by Steven Vogt of the University of California, Santa Cruz, Paul Butler of the Carnegie Institution of Washington in DC, and their colleagues.

Unlike the four previously known planets in the same system and hundreds of others found throughout the Milky Way galaxy, Gliese 581 g sits in the middle of its host star's habitable zone, where temperatures are in the right range for liquid water to exist. It is also puny enough – weighing about three Earths – to have what is likely a rocky, solid surface.

But it might be too early to claim a definitive detection. A second team of astronomers have looked for signals of Gliese 581 g in their own data and failed to find it.

"We easily recover the four previously announced planets, "b", "c", "d", and "e". However, we do not see any evidence for a fifth planet in an orbit of 37 days," says Francesco Pepe of the Geneva Observatory in Switzerland. He presented the results on Monday at an International Astronomical Union symposium in Turin, Italy. ...

via First life-friendly exoplanet may not exist - space - 13 October 2010 - New Scientist.