The evolutionary tracks corresponding to the case 1 (left) and case 2 (right) are represented with the observational error box (the 1σ-error box (log T_eff, log L) in red and the diagonal dotted lines for R). The mass (in solar units) is indicated at the beginning of the evolutionary tracks. In each case, the best model is shown as full line, whereas the two extreme models are shown as dashed lines. For the best model, we show in brackets for several time steps (open circles) the evolution of the mean large separation (μHz), the radius (R_⊙), and the age (Gy). The full circles represent the time at which the large separation equals the observed one, i.e. 50.9   μHz. (See online edition for a color version.)