Stability analysis of the rotation rate close to the synchronization for δ = 0.1, α ∈ [ 0.25:0.5 ], and (B − A) /C ∈ [ 0:0.9 ]. We adopt three different initial obliquity values ψ = 1°, 30°, and 60°. The color index indicates the proportion of chaotic orbits inside the studied domain: from dark blue for fully regular to red for entirely chaotic. The dashed line (Eq. (11)) roughly delimits the zone where chaotic motion is possible. The dots identify two representative cases that we detail in Fig. 3.