Maximum radiative luminosity (scaled to ﹩M=1M_{\mathrm{J}\,}﹩; see eq. [7]) that can be carried by radiative diffusion vs. temperature along adiabats. The temperature T should be interpreted as ﹩T_{\mathrm{rcb}\,}﹩, the temperature at the radiative‐convective boundary. The five curves are for entropies ﹩Sm_{p}/ k_{\mathrm{B}\,}=6,\ldots ,10﹩, from bottom to top.