Spin derivative dΩ/dt(rad s⁻²). The left panel shows the spin derivative as a function of the rotation state Ω/n (Ω and n are the spin and mean motion, respectively), for different eccentricities. The green dots (filled and empty) represent the equilibrium states, stable (i.e., SORs) and unstable, respectively. The middle and right panels represent the spin derivative and the eccentricity derivative as a function of the rotation state Ω/n and the eccentricity, respectively. The red colored areas depict the positives values, the blue areas depict the negative values, and the red line corresponds to dΩ./dt = 0. The dotted lines represent the two eccentric cases in the left panel (e = 0.1 and e = 0.2). The arrows represent the evolutions presented in Fig. 8.