Evolution of a 12 M_⊙ single-star model from Set IV. Accretion begins when the central hydrogen mass fraction reaches 0.5 and proceeds at a constant rate of 5 × 10⁻⁴ M_⊙ yr⁻¹ until the stellar mass grows to 20 M_⊙. The specific angular momentum of the accreted material is artificially reduced by a factor of ten to enable continued accretion after the star first reaches critical rotation. The panels are the same as those in Fig. C.1. The thick lines highlight the accretion phase.