Parameters of the synthesized population of HeS stars. Upper panel: distribution of the surface He-abundance (nHe/nH); middle panel: log of surface gravity (log(g)); lower panel: HRD. The symbols are the same as in Fig. 6. The gray scales in all panels show the Galactic number of systems per pixel. The colors in the left panels encode the masses of HeS stars, while the colors in the right panels encode the masses of H/He envelopes.