(a) Surface equatorial rotational velocity for single-star models as a function of evolutionary ages until the end of the calculation. (b) Surface equatorial rotational velocity for two components in binarities as a function of evolutionary ages. (c) Evolution of the ratio of angular velocities to the critical angular velocity (i.e., ﹩\tfrac{{\rm{\Omega }}}{{{\rm{\Omega }}}_{\mathrm{cric}}}﹩) for single stars. (d) Evolution of ﹩\tfrac{{\rm{\Omega }}}{{{\rm{\Omega }}}_{\mathrm{cric}}}﹩ for two components in binarities. Different evolutionary points of the star are marked with different symbols: circles—the terminal of main sequence; crosses—the beginning of the central helium burning; squares—the end of the central helium burning.