Kiel diagram showing the five different regions of model coverage (O, B₁, B₂, BSG₁, and BSG₂). Overlayed are Ekström et al. (2012) evolutionary tracks for rotating stars (v_ini/v_crit = 0.4) at solar metallicity (black lines) for different masses, as indicated. The five-pointed black stars mark the positions of the single stars analysed in the present work and the matching open symbols are the components in the analysed binary systems.