Top: comparison of the luminosity variation of the CO⁵BOLD model st28gm06n26, both averaged over all directions (orange) and only in the +x direction (green), as well as the luminosity variation of the DARWIN l70t27 u_p = 2km s⁻¹ and 4 km s⁻¹ models (grey and black). Bottom: comparison of the inner-most mass shells, representing the inner radial boundary, of the DARWIN l70t27 u_p = 2km s⁻¹ and 4 km s⁻¹ models (grey and black) and the mass shell at a comparable distance from the CO⁵BOLD model st28gm06n26, averaged over all directions (orange). This is the same time-interval as the top panel of Fig. 6.