Periodograms of the residuals RVs parametrised by the model complexity (name convention as in Eq. (5)). All the periodograms are normalised according to their respective 1% FAP level (horizontal dotted-dashed line). The RV rms of the residuals for each model is indicated in the legend as well as the integrated power between 32 and 45 days. Top: results obtained by increasingly adding shell basis coefficients into the multi-linear model of Eq. (5). Once three shell basis coefficients are fitted, the rotational period is no more significant (green and red). Bottom: comparison between the residuals obtained after fitting for four shell basis coefficients (red) or the three classical CCF moments (FWHM, VSPAN and contrast) plus the CaII H&K. Both CCF moments before (CCF^{Y 0}, blue) and after YARARA processing (CCF^{Y 1}, green) were used.