Mock CHE models described in Sect. 2 on the Hertzsprung-Russell diagram. Colors indicate different evolutionary stages, including the ZAMS, TAMS, helium ZAMS and TAMS, and core carbon depletion (C dep.). Simulations cover the mass range 6.3–251 M_⊙ and were performed without mass loss. Different line styles indicate different metallicity values. Two evolutionary tracks with a metallicity of Z_⊙/50 and masses of 10 M_⊙ and 100 M_⊙ are shown in gray for reference.