Same as Fig. B.1, now for Δv_⋆ against the fraction of young stars. The scenario is similar to that for the age: we do not have any trends in the discs and nuclei of the four galaxies, which present almost vertical distributions. In the case of the rings we find increasing values of the difference in velocity with increasing values of the fraction of young stars for NGC 1097, but similarly to what happened with age, the trend is not reliable since the mean values of Δv_⋆ are comparable to the typical error. For the other rings we do not observe any clear trend.