Radial velocity distribution of γ Vel (left panel) and Cha I (right panel) stars. Thick (red) and thin (blue) lines represent the histograms of “lithium members” and targeted nonmembers, respectively. Lithium members fulfilling also the RV criterion are represented by the red hatched area. In γ Vel there is a double peak in the RV distribution of members and a total absence of such peaks for nonmembers.