Temporal evolution of the internal structure of stars with M_final = 1 M_⊙ and X_D = 28 ppm in the cases of a classical, non-accreting model (panel a) and accreting models (panels b–e). The vertical axes are the mass coordinates normalized by stellar mass. The shaded regions indicate the convective regions and the lines show the base of the surface CZ. In panels b, c, and e, ξ = 0.5, 0.1, and 0, respectively, with uniform heat distribution. In panel d, the non-uniform heat distribution is assumed: ξ = 0.1 and m_ke = 0.1. For comparison, each panel includes the dotted line in panel a. In addition, the CZ base of panel c is also illustrated in panel d by the green dashed line.