³He profile (in mass fraction) at the main-sequence turnoff for models of various masses as indicated and for two values of the metallicity (Z = 10^-4 and Z_⊙ in the left and right subpanels respectively). The horizontal arrows indicate the initial ³He content assumed at stellar birth. The vertical lines show, in each case, the maximum depth reached by the convective envelope during the first dredge-up. (Left) Standard models. (Right) Models including rotation-induced mixing, assuming an initial rotation velocity equal to 45% of the critical velocity on the zero age main sequence; for the [2, 4 M_⊙; Z_⊙ and Z = 10^-04] rotating models, the dotted curves correspond to predictions assuming V_ZAMS/V_crit ~ 0.90.