Tidal evolution in exoplanets: The case of the two super-Earths around CoRoT 7
Seminar Room 1, Newton Institute
The CoRoT space telescope has detected one small planet around the G9V star now designated as CoRoT 7. The observation of this star with the spectrograph HARPS allowed the mass of the planet to be determined as 4.8 Earth masses - a super-Earth. In addition, it unraveled one second small planet (mass 8.4 Earth masses) around the star. The analysis of the radial velocities has been strongly impaired by the activity of the star. The inner planet (CoRoT 7b) is very close to the star (0.017 AU) and is expected to be under strong tidal influence which, in the past, may have circularized its orbit and synchronized its rotation (spin-orbit resonance). The (quasi-) conservation of the angular momentum of the system formed by the two planets may have delayed the circularization of the orbit of the inner planet, and forced the outer planet (CoRoT 7c) also to have its orbit circularized. Currently both planets may have eccentricities close to zero and no tidal dissipation is expected to be occurring inside them; the continuous decay of the planet would be now controlled only by the tidal dissipation in the star.