Upper panel: Lomb-Scargle periodogram of the observed RV variations produced by stellar activity excluding the four data points between HJD 2 454 308.0 and 2 454 310.0 (solid line) and the periodogram of the corresponding synthetic time series (dash-dotted line); Middle panel: Lomb-Scargle periodogram of the observed RV variations produced by stellar activity excluding the four data points between HJD 2 454 308.0 and 2 454 310.0 (solid line) and the periodogram obtained after subtracting the synthesized RV variations from the observed RV time series (dotted line). The vertical dashed lines mark the rotation frequency and its harmonics for a rotation period of 11.953 days. Lower panel: the spectral window of the time series of the RV observations considered in the upper panel.