Evolution as a function of stellar age of the mass (top left panel), radius (top right panel), effective temperature (middle left panel), luminosity (middle right panel), internal structure constant of the star (bottom left panel), and apsidal motion rate of the binary (as computed with Eq. (22) assuming both stars are described with the same Clés model, bottom right panel) for Clés models with initial masses of 30.0 (green), 31.0 (light blue), and 32.0 M_⊙ (pink), overshooting parameter of 0.20, Z = 0.015, and no turbulent diffusion. Stellar mass-loss was computed according to the formalism of Vink et al. (2001), with ξ = 1. The observational value of the corresponding parameter and its error bars are represented by the solid red line and the dashed dark red horizontal lines, respectively. The dark blue line represents the Claret (2019) model with an initial mass of 30.0 M_⊙ and ξ = 0.1.