Time evolution of T_eff for the same model with T_eff = 5500 K, log 𝑔 = 5.0, and [Fe/H] = −4.0. The top panel shows the original non-relaxed model from the grid, with T_eff decreasing quite quickly, while the new relaxed model is shown in the bottom panel. The solid grey lines indicate the mean T_eff at a given time step, while the dashed lines are spaced out by 1–σ (standard deviation).