We investigate the dynamical evolution of the potentially habitable super-earth GJ 667Cc in the multiple system of at least two exoplanets orbiting a nearby M dwarf , paying special attention to its spin-orbital state .
The published radial velocities for this star are re-analyzed and evidence is found for additional periodic signals , which could be taken for two additional planets on eccentric orbits .
Such systems are not dynamically viable and break up quickly in numerical integrations .
The nature of the bogus signals in the available data remains unknown .
Limiting the scope to the two originally detected planets , we assess the dynamical stability of the system and find no evidence for bounded chaos in the orbital motion , unlike the previously investigated planetary system of GJ 581 .
The orbital eccentricity of the planets b and c is found to change cyclicly in the range 0.06 - 0.28 and 0.05 - 0.25 , respectively , with a period of approximately 0.46 yr , and a semimajor axis that little varies .
Taking the eccentricity variation into account , numerical integrations are performed of the differential equations modeling the spin-orbit interaction of the planet GJ 667Cc with its host star , including fast oscillating components of both the triaxial and tidal torques and assuming a terrestrial composition of its mantle .
Depending on the interior temperature of the planet , it is likely to be entrapped in the 3:2 ( probability 0.51 ) or even higher spin-orbit resonance .
It is less likely to reach the 1:1 resonance ( probability 0.24 ) .
Similar capture probabilities are obtained for the inner planet GJ 667Cb .
The estimated characteristic spin-down times are quite short for the two planets , i.e. , within 1 Myr for planet c and even shorter for planet b .
Both planet arrived at their current and , most likely , ultimate spin-orbit states a long time ago .
The planets of GJ 667C are most similar to Mercury of all the Solar System bodies , as far as their tidal properties are concerned .
However , unlike Mercury , the rate of tidal dissipation of energy is formidably high in the planets of GJ 667 , estimated at 10 ^ { 23.7 } and 10 ^ { 26.7 } J yr ^ { -1 } for c and b , respectively .
This raises a question of how such relatively massive , close super-Earths could survive overheating and destruction .