March 2010 — Artist's impression of Corot-7b
Researchers using the HARPS spectrograph attached to ESO’s 3.6-metre telescope at the La Silla Observatory in Chile have firmly established the nature of the smallest and fastest-orbiting exoplanet known, Corot-7b. This planet has a mass five times that of Earth and a radius a bit less than twice that of our terrestrial home, establishing its density as similar to that of our solid world. Corot-7b is also the closest known exoplanet to its host star, which also makes it the fastest moving — it orbits its Sun-like star at a speed of more than 750000 kilometres per hour. Its proximity to the star means that Corot-7b must experience extreme conditions. The probable temperature on its “day-face” is above 2000 degrees Celsius, but minus 200 degrees Celsius on the night side. Theoretical models suggest that the planet may have lava (as shown in this artist’s impression) or boiling oceans on its surface. A sister planet, Corot-7c, is the bright speck seen in the distant sky to the right.
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