Variation of physical parameters in the 15 M_⊙ models. Left panel: Evolutionary tracks during the MS phase in the Hertzsprung-Russell diagram for models C, D, E, and F (see Table 1) as a function of the Lagrangian mass for the 15 M_⊙ at Z = 0.014 and with V_ini/V_crit = 0.4. Middle panel: Abundance of hydrogen in mass fraction ranging from the center to the outer envelope of the models when the central mass fraction of hydrogen is X_c = 0.35. Right panel: Variations in the angular velocity vs. the mass coordinate for the same models as are shown in the middle panel.