Flux density arising from starplanet interaction as a function of the stellar mass-loss rate (panels a and b) and the magnetic field of the planet (panels c and d). (a) Expected flux density for a closed dipolar geometry. (b) Expected flux density for an open Parker spiral geometry. (c) Expected flux density for a closed dipolar geometry. (d) Expected flux density for an open Parker spiral geometry. For (c) and (d) we assume Ṁ = 0.1 Ṁ_⊙. Note that the resulting radio emission is unaffected by the magnetic field of the planet, unless the latter is very large (~4 G for closed dipole or even > 10 G for a Parker spiral). The emission expected from Saur/Turnpenney’s model is shown in orange, and the emission expected from Zarka/Lanza’s model is shown in blue. The overlap between both models is shown in brown. The dashed black line represents the assumed detection threshold of 100 μJy.