Top: binding energy of the envelope plotted as a function of radius. On the top x-axis we have indicated the orbital separation assuming a neutron star companion with a canonical mass of 1.4 M_⊙, for reference. Our solar models are shown in the top left panel where we show the binding energy of the helium envelope. Our low-metallicity models are shown in the top-right panel, where we show the binding energy of the hydrogen envelope (cf. Sect. 3.3 and Fig. 5). Bottom: final separation after the common envelope evolution of stripped stars with neutron star companions as a function of the initial separation at solar (left) and low (right) metallicity. Stars with a pre-CE convective envelope are marked with colors, which indicate the mass of the stripped star, assuming a common envelope efficiency parameter α_CE = 1.