Top: evolution of the mass-loss rate Ṁ (in M_⊙ yr⁻¹) as a function of the fractional abundance of hydrogen in the convective core X_core/X₀ for a 15 M_⊙ star with Z = 0.02 and for ω_i = 0.5. The vertical dashed line marks the evolutionary time at which the star reaches a TWR. The vertical dotted line marks the transition between Phase 1 and 2. Bottom: same but for the angular velocity at equator in units of the equatorial critical angular velocity ω = Ω_eq/Ω_k. The red dashed line corresponds to the evolution of ω with constant mass and angular momentum throughout the MS.