Fraction of planets with radial velocity higher than 20 m s⁻¹ as a function of the metallicity for the model computing the internal structure with a reduced opacity. Top panel: seeds starting after 1.5 Myr of the disc evolution and the bottom panel for t_ini = 2 Myr. The red line shows the percentages of planets with a radial velocity higher than 20 m s⁻¹. The blue line is the percentages of planets that have a radial velocity higher than 20 m s⁻¹ and that can be observed according to the detection probability of Mayor et al. (2011). The black line represents the observation fit given by Johnson et al. (2010, Eq. (21)) and the grey area the uncertainty on this fit.