Time evolution of log(T_eff), top panel; R, middle; and surface metal abundance Z_surf, bottom, for 90 M_⊙ solar-metallicity stars rotating at v/v_crit = 0.0 and 0.4. We measured these parameters at the surface of the hydrostatic core because we calculated them for the highly clumpy winds. We divided the time axis into two equal halves as in Fig. 2, but here the second half of the range extends from 3 − 4 Myr.