Dynamical maps of polar orbits (i = 90°, Ω = 90°) for massive planets in the (q, M_p) plane with e_B = 0.5. The colour scale in the upper and lower panels corresponds to ΔΩ and Δ(Ω − ϖ_B), respectively. Initially, the planet is located at the equilibrium point i = 90°, Ω = 90°. The four initial conditions identified with white circles correspond to the orbits shown in Fig. 9. Each system was integrated for 20 000 yr (~ 650 000 binary periods).