Interior silicate mass fraction (top) and temperature profile (bottom) of 5 M_⊕ (left), 10 M_⊕ (middle) and 20 M_⊕ (right) planets. The profiles are shown at the end of formation (dashed), after the rapid contraction (dotted), and after 1, 5, 10 Gyr (solid) for an evolution at 0.2 AU. The early contraction (from a Hill sphere to about one-tenth of it) is the cause of the gas temperature increase between the formation and the million-year curves. The increase in the central temperatures is the result of core contraction due to the constant core density assumption in the formation model. The dashed and dotted lines of the 20 M_⊕ model overlap in the top right panel.