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Since the discovery of the transiting super-Earth CoRoT-7b, severalinvestigations have yielded different results for the number and masses ofplanets present in the system, mainly owing to the star's high level ofactivity. We re-observed CoRoT-7 in January 2012 with both HARPS and CoRoT, sothat we now have the benefit of simultaneous radial-velocity and photometricdata. This allows us to use the off-transit variations in the star's lightcurve to estimate the radial-velocity variations induced by the suppression ofconvective blueshift and the flux blocked by starspots. To account foractivity-related effects in the radial-velocities which do not have aphotometric signature, we also include an additional activity term in theradial-velocity model, which we treat as a Gaussian process with the samecovariance properties (and hence the same frequency structure) as the lightcurve. Our model was incorporated into a Monte Carlo Markov Chain in order tomake a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We measurethe masses of planets b and c to be 4.73 +/- 0.95 Mearth and 13.56 +/- 1.08Mearth, respectively. The density of CoRoT-7b is (6.61 +/- 1.72)(Rp/1.58Rearth)^(-3) g.cm^(-3), which is compatible with a rocky composition. We searchfor evidence of an additional planet d, identified by previous authors with aperiod close to 9 days. We are not able to confirm the existence of a planetwith this orbital period, which is close to the second harmonic of the stellarrotation at around 7.9 days. Using Bayesian model selection we find that amodel with two planets plus activity-induced variations is most favoured.

Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system