Periodograms (top) and corresponding RVs (bottom) for three different slices of 31 days for the activity simulation shown in Fig. 5 (). In the periodograms the horizontal line corresponds to the 1% false-alarm probability and the vertical dashed lines to the rotational period of the star, P_rot, as well as P_rot/2 and P_rot/3. On the RV plots, the dots correspond to the simulated RVs and the triangles to a fitted function with three sin waves of period P_fit, P_fit/2 and P_fit/3 (P_fit is a free parameter). P_rot as well as the rms of the simulated RVs can be found in the upper left part of the plot. P_fit as well as the rms of the corrected RVs (simulated minus fitted sine waves) can be found in the upper right part of the plot.