Zoom-in of the Kippenhahn diagram close to the edge of the CO core where the Ne-burning shell ignites at a mass coordinate of 1.54 M_⊙ and develops a convective region just above it that then merges with the He-burning shell after about 10 d. The solid lines, and patch colors are the same as in Fig. 4. The dashed lines correspond to the radius (black, dashed), the Roche lobe radius (red, dashed) and the volume-equivalent radius of the outer Lagrangian point (red, dotted).