TULIPS diagram (Laplace 2022) of the nuclear energy generation rate ϵ_nuc at the end of core oxygen burning (central oxygen mass fraction < 10⁻⁴). Shown are the interiors of a single star of M_ini = 20 M_⊙ (bottom), an early Case B accretor model of M_ini = 20 M_⊙ and f_acc = 0.1 (top left), and an early Case B accretor model of M_ini = 23 M_⊙ and f_acc = 1.0 (top right). The three models have a similar CO core masses of M_CO = 5.62 M_⊙, 5.64 M_⊙, and 5.89 M_⊙, respectively. The f_acc = 0.1 accretor model is a CSG while the f_acc = 1.0 model is a BSG, which can be recognised by the strong hydrogen-shell burning that drives a thick convection zone (not indicated here for clarity, but cf. Figs. 2 and A.5).