Nuclear energy generation rates by hydrogen (red lines) and helium burning (green lines), temperature profile (purple line), and internal hydrogen profile (cyan lines) as a function of interior mass for the considered 10 M_⊙ star. The horizontal black dotted line represents the temperature T = 2.0 × 10⁷ K at which hydrogen burning becomes active. Panels E, F, G, and H correspond to the evolutionary points labelled E, F, G, and H in Fig. 1, respectively. We note that the hydrogen abundance has been shifted upward in order to match the scale of the right-hand axis, that is 4X_H + 5. Left panels: for the 10 M_⊙ stars with Z = 0.014 but with different initial rotational velocities of v_ini = 0 km s⁻¹, 120 km s⁻¹, 350 km s⁻¹. Right panels: for the 10 M_⊙ stars with Z = 0.0008 but with different initial rotational velocities of v_ini = 0 km s⁻¹, 120 km s⁻¹, 350 km s⁻¹.