Internal structure of the reference model (solid lines) used as initial model for the 2D simulations compared to a model for the current Sun (dashed lines). The figure shows the density ρ (in g cm⁻³), temperature T (in K) and radiative diffusivity κ_rad = χ/(ρc_P) (in cm² s⁻¹), with c_P the specific heat at constant pressure. The Schwarzschild boundary is indicated by the vertical solid line for the reference model and the vertical dashed line for the Sun-like model.