October 5, 2009

Exoplanet’s atmosphere ‘rains’ pebbles

U.S. scientists say they have used simulations to determine the atmosphere of an exoplanet discovered in February is hot enough to rain pebbles.

Researchers at Washington University in St. Louis say their models show the exoplanet is close enough to its star that its day-face maintains a temperature of about 4,220 degrees Fahrenheit -- hot enough to vaporize rocks.

The theoretical models suggest the planet has an atmosphere of the components of rock in gaseous form and lava or boiling oceans on its surface. According to simulations, Corot-7b's atmosphere is made up of the ingredients of rocks and when a front moves in, pebbles condense from the air and rain into lakes of molten lava below.

The only atmosphere this object has is produced from vapor arising from hot molten silicates in a lava lake or lava ocean, Professor Bruce Fegley Jr., who led the study, said.

The study that included research assistant Laura Schaefer appears in The Astrophysical Journal.