Internal structure of the 2.1 M_⊙-model represented in Fig. 8. The profiles are represented as a function of the outer mass fraction and at various evolutionary steps. Upper panel: iron abundance profiles, ⁵⁶Fe/⁵⁶Fe₀ represents the ratio between the current Fe abundance and its initial value (cf. Table 3). The various curves are defined in the upper panels and are valid for all the plots of the respective column. Middle panel: Rosseland opacity profiles. Lower panel: difference between the radiative and adiabatic gradients.