Evolution of the size of CoRoT-17b (radius in Jupiter units) as a function of age (in billion years), compared to constraints inferred from CoRoT photometry, spectroscopy, radial velocimetry, and the PADOVA stellar isochrones. Green, blue, and yellow-green plain regions correspond to the planetary radii and ages that result from stellar evolution models that match the inferred ρ_star − T_eff uncertainty ellipse within 1 − 3σ, respectively. Planetary evolution models for a planet with a solar-composition envelope and no dissipation are shown as plain lines and labelled according to the value of the core mass (in earth masses); models in which 0.25% of the incoming flux is deposited at the planet’s centre are shown as dotted lines. Models with no core are shown in black, and with a core in red. These models assume a total mass of 2.43 M_Jup and an equilibrium temperature of 1626 K.