Core temperature vs. entropy. The three distinct lines are the masses ﹩M/ M_{\mathrm{J}\,}=0.32﹩, 1.0, and 3.2, from bottom to top. For each mass, the irradiation temperatures ﹩T_{\mathrm{deep}\,}( \mathrm{K}\,) =500,\ldots ,3500﹩ are plotted, but there is so little dependence on ﹩T_{\mathrm{deep}\,}﹩ that the curves are indistinguishable.