Kippenhahn diagrams (similar to Fig. 4) of the simulation with q = 0.25, C_d = 0.23, and C_h = 4.0, showing the Mach number (ℳ= v_r/c_s) in panel a, velocity divergence (dv/dr) in panel b, specific entropy (s) in panel c, and opacity (κ) in panel d. The white hatched zones in panel c indicate convective mixing. For a better visualization of the velocity divergence, the log modulus transformation, logmod(x) = sgn(x)log₁₀(|x|+1), is used (John & Draper 1980). The arrows in panel b roughly indicate the recombination zones of H I, He I, and He II (see also Figs. 4b–d).