1.8 times larger than Earth
The small exoplanet CoRoT-7b detected by CNES’s CoRoT spacecraft has turned out to be the 1st rocky planet discovered outside our solar system with a density similar to Earth’s, according to results published Wednesday.
The astronomers who announced the planet’s discovery in February have now calculated its mass and density, revealing that it is a rocky world, indicated the European Southern Observatory (ESO).
“This is the ultimate reward: we’ve hit an Earth analogue,” Didier Queloz from the Geneva Observatory, leader of the team who made the discovery, told AFP. “CoRoT-7b justifies all the efforts that have gone into CoRoT.”
The small planet, with a diameter 1.8 larger than Earth, is very close to its star and its mass is five times that of Earth, according to data acquired by the HARPS spectrograph on ESO’s telescope at La Silla, Chile.
“Until now, we had no way of knowing the composition of all these small planets we’re finding,” explains Didier Queloz. He added: “But as CoRoT-7b is rocky, it’s likely that similar planets with a mass 3 to 5 times that of Earth are rocky too.” So far, 10 such “super Earths” have been discovered.
“This makes CoRoT-7b a casebook study,” underlined Queloz, among the 374 planets detected outside our solar system that have been classified and categorized. “The most massive are gas giants like Jupiter, which formed a long way from their star before being pulled closer in. We call these hot Jupiters.”
Furthermore, observations by ESO detected the presence of a second planet, named CoRoT-7c, with a mass 8 times that of Earth.
Everything seems to point to the 1st planetary system found with 2 super Earths, each with a mass less than 10 times that of Earth.