Bottom: star activity resulting from the high-pass filter. The labels [4H] and [3H] indicate the results obtained respectively with 4 and 3 harmonics. The color coding of the components of these curves, when visible, is the same as in Fig. 7. The dots indicate the measured radial velocities with their error bars. The error bars of the activity estimated with the 4-harmonic high-pass filter are also shown. Top: difference between the results labeled 4H and 3H.