Since the discovery of the transiting super-Earth CoRoT-7b , several investigations have yielded different results for the number and masses of planets present in the system , mainly owing to the star ’ s high level of activity .
We re-observed CoRoT-7 in January 2012 with both HARPS and CoRoT , so that we now have the benefit of simultaneous radial-velocity and photometric data .
This allows us to use the off-transit variations in the star ’ s light curve to estimate the radial-velocity variations induced by the suppression of convective blueshift and the flux blocked by starspots .
To account for activity-related effects in the radial-velocities which do not have a photometric signature , we also include an additional activity term in the radial-velocity model , which we treat as a Gaussian process with the same covariance properties ( and hence the same frequency structure ) as the light curve .
Our model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c .
We measure the masses of planets b and c to be 4.73 \pm 0.95 M _ { \oplus } and 13.56 \pm 1.08 M _ { \oplus } , respectively .
The density of CoRoT-7b is ( 6.61 \pm 1.72 ) ( R _ { p } / 1.58 R _ { \oplus } ) ^ { -3 } g.cm ^ { -3 } , which is compatible with a rocky composition .
We search for evidence of an additional planet d , identified by previous authors with a period close to 9 days .
We are not able to confirm the existence of a planet with this orbital period , which is close to the second harmonic of the stellar rotation at \sim 7.9 days .
Using Bayesian model selection we find that a model with two planets plus activity-induced variations is most favoured .