Quantities extracted along the sonic surface. We only show r > 6 au (where r is the spherical radius) since there is no coherent transsonic flow interior to 6 au. Top left: the gas (blue) and dust (orange) temperatures. For reference the dashed line shows the escape temperature of Owen et al. (2012) and the dotted lines are fits to the hot isothermal section, molecular section and outer section. Top right: the gas density, with fits to the same sections. Bottom left: the proportion of H in H⁺ (red), H (green) and H₂ (blue). Bottom right: the fraction of the thermochemical cooling given by each major category of cooling.