Left: schematic representation of the heat flux (in log units) from tidal heating (black line) and convective heat transport (gray) as a function of temperature. Two equilibria are possible: point (A) represents a balance between tidal heating and convection in a purely solid mantle (T_eq is less than the solidus temperature T_s). This stateis depicted schematically in the middle panel. Point (B) represents an equilibrium for which T_eq > T_s, implying a partially molten rock mantle exists within the planet. This state is shown schematically in the right panel.