Propagation and Kippenhahn diagrams for the M_⋆ = 6.0 + 2.4 M_⊙ merger product and M_⋆ = 7.8 M_⊙ genuine single star. Panels (a) and (c) show propagation diagrams for ℓ = 1,  2 and m = 0 modes without rotation for the merger product with M_⋆ = 6.0 + 2.4 M_⊙ and genuine single star with M_⋆ = 7.8 M_⊙, respectively. The black (grey) dots represent the radial nodes of the oscillation modes, or more specifically, the locations where the radial wave displacement ξ_r(r) = 0 for the ℓ = 1 (ℓ = 2) modes. The purple regions show the g-mode cavity or cavities, while the orange region shows the p-mode cavity. Panels (b) and (d) show Kippenhahn diagrams for the merger product with M_⋆ = 6.0 + 2.4 M_⊙ and a genuine single star with M_⋆ = 7.8 M_⊙, respectively. The dash-dotted green lines indicate the models for which the respective propagation diagrams in Panels (a) and (c) are shown, which is when their HRD tracks overlap, indicated by the violet box in Fig. 1a. Both Kippenhahn diagrams show the evolution of the models up to core-helium exhaustion.