Evolutionary tracks for masses from 0.8 to 1.15 M_⊙ in step of 0.05 M_⊙ (blue solid curves) in a HR diagram. The black dots indicate the location of the synthetic targets stars studied here. The magenta dashed line shows the location of models with their central hydrogen content X_c ∼ 10⁻⁶ which we take here as the transition between MS stars and subgiant phases. The transition follows the empirical relation : log L/L_⊙ = 10 (log T_eff − 3.7532)+0.25 for that range of mass given the adopted chemical composition and physics of the stellar models.