Upper six panels: envelope mass fraction M_e∕M as a functionof planet mass M for 6 different orbital distances. The dashed lines show the envelope mass fraction at 5 Gyr,while the dotted lines show the initial (postformation) envelope mass fraction M_e,0 ∕M. The simulations M0–M4 from Figs. 4 and 5 are shown to display the consequences of different initial conditions. Lower six panels: corresponding mass-radius relations compared to observations. In each panel, the solid and dashed lines correspond to the lower and upper limit of the distance interval, respectively. Black dots with error bars show the observed extrasolar planets orbiting stars with masses between 0.7 and 1.3 M_⊙ in these distance intervals.