Evolutionary trends of 8 M_⊙ He stars with ω/ω_crit = 0 and ω/ω_crit = 0.8, and internal structure of 8 M_⊙ HeZAMS star with ω/ω_crit = 0.8. Upper panel: HR diagram of the evolutionary tracks of 8 M_⊙ He stars with ω/ω_crit = 0 and ω/ω_crit = 0.8. Middle panel: evolution of rotation rate and mass with time. The x-axis shows time (unit: million years; zero point: HeZAMS). The red dotted and solid lines represent He stars with ω/ω_crit = 0 and ω/ω_crit = 0.8, respectively, corresponding to the red y-axis on the left. The blue solid line represents the rotational velocity of the He star with ω/ω_crit = 0.8, corresponding to the blue y-axis on the right. Lower panel: stellar mixing coefficients and the pressure scale height as a function of radius at HeZAMS. The red solid and dotted lines represent the convective mixing coefficient and the rotational mixing coefficient, respectively, corresponding to the red y-axis on the left. The blue solid line represents the pressure scale height, corresponding to the blue y-axis on the right.