Hertzsprung–Russell diagram showing the evolutionary tracks of models with initial masses of 2.4, 4, 9 and 18 M_⊙. Arrows along the tracks indicate the direction of evolution. The resulting stripped stars have masses of 0.44, 0.8, 2.5 and 6.7 M_⊙. Mass transfer is marked with an underlying thick, gray line. Helium core burning is marked with yellow and dark orange color corresponding to the central helium mass fractions in the ranges 0.95 > X_He,c > 0.9 and 0.9 > X_He,c > 0.05, respectively.These models have solar metallicity.