Map representing contours of the average surface heat flux φ_tides, as a function of eccentricity and planetary dissipation factor. From left to right the full lines correspond to a flux of 10^-6, 10^-4, 10^-2 1, 10², 10⁴, 10⁶, 10⁸, 10¹⁰ W m^-2. The long dashed lines correspond to a temperature of 10, 10², 10³ and 10⁴ K. The observed value of φ_tides on Io, 2.4–4.8 W m^-2 (Spencer et al. 2000), is indicated in black for its estimated eccentricity value of 4.3 × 10^-3 (Murray & Dermott 1999).