Final fate of a post-CE binary system composed of a naked helium core and a BH as a function of orbital separation after envelope ejection. The chosen donor star model is that of the 88M_⊙ star (Z = Z_⊙/ 50) at its maximum extent as a giant, cf. Figs. 3 (lower panel) and 4. The mass of the exposed helium core is M = 52.35M_⊙ and the BH is assumed to have a mass of 30M_⊙. The blue line (GWR) represents the merger time due to gravitational-wave radiation, the orange line (SN) represents the remaining lifetime of the core until it collapses, and the red dotted line (Wind) represents the timescale (a/ȧ_wind) of orbital widening due to stellar wind mass loss. The yellow shaded region marks the core region (X_H< 0.10). See Sect. 4.5.