page_title: CoRoT-7b
section_title: Model of the interior
hierarchical_section_title: CoRoT-7b / Characteristics / Model of the interior
caption_attribution_description: English: Artist view of Corot-7b, the first discovered Super-Earth exoplanet with fair estimate of size, mass and density
context_page_description: CoRoT-7b is an exoplanet orbiting around the star CoRoT-7, in the constellation Monoceros, at 489 light years from Earth. It was first detected photometrically by the French-led CoRoT mission and reported in February 2009. Until the announcement of Kepler-10b in January 2011, it was the smallest exoplanet to have its diameter measured, at 1.58 times that of the Earth, and the first potential extrasolar terrestrial planet to be found. The planet has a very short orbital period, revolving around its host star in about 20 hours.
  Combination of the planet's diameter derived from transit data with the planet's mass derived from radial velocity measurements, meant that the density of CoRoT-7b was about the same as that of Earth and, therefore, that CoRoT-7b was a terrestrial planet like Earth and was not a gas giant like Jupiter. The radial velocity observations of CoRoT-7 also detected a second super-Earth, CoRoT-7c, which has a mass 8.4 times that of Earth and orbits every 3.7 days at a distance of 6.9 million km.
context_section_description: The uncertainty in CoRoT-7b mass does not allow precise modelling of the planet structure. Nevertheless, educated guesses could still be put forth. Assuming a 5-Earth-masses planet, the planet was modeled to have convection in the mantle with a small core with no more than 15% the mass of the planet, or 0.75 M⊕. The lower mantle above the core-mantle boundary has more sluggish convection than the upper mantle because the greater pressure causes fluids to become more viscous. The temperature of the upper convecting mantle is different from one side of the planet to the other with lateral temperature differences for downwellings up to several hundred kelvins. However, the temperature of the upwelling is unaffected by downwelling and surface temperature variations. On the permanent dayside of the tidally locked planet where the surface temperature is hot from continuously facing its sun, the surface takes part in convection, which is the evidence that all the surface of this hemisphere being covered in oceans of lava. On the permanent nightside, the surface is cool enough for the formation of the crust with pools of lava above the convective mantle with intense volcanism. The dayside of the planet has larger convection cells than the nightside. Researchers also investigated the physical state of the interior of CoRoT-7b, indicating as likely a solid iron core, thus a self-generated magnetic field should be absent on the planet.
caption: CoRoT-7b artist view.
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