Internal structure profiles with and without penetrative convection. Left: temperature gradients as function of acoustic radius for the B1 and B2 models with M = 1.4 M_⊙ and X_c = 0.15. The grey lines represent the adiabatic and radiative gradients of model B2 (which are very similar to those of B1). The vertical dashed black line on the right represents the position of the Schwarzschild limit for both models. The line on the left represents the bottom of the penetrative convective region of model B2. The downward arrow shows the middle of the acoustic cavity (tcz/𝒯 ≈ 4180 s). Right: dΓ₁/dτ as a function of the acoustic radius for models B1 and B2.