Top panel: distribution of the source stars M_cut values derived from the CEMP star sample (red) and the entire sample (blue). Middle panel: energy required to unbind the source star material above the considered M_cut. It is computed as with M_fin the final source star mass (see Table 2). Bottom panel: derivative of E_UB as a function of M_cut. The shaded regions show the approximate unexplored M_cut region (below the bottom of the He-shell).