Schematic view of the different interactions acting on the initial particle disk. Curves of constant angular momentum (per unit mass) are shown in gray, with arrows indicating evolutionary routes due to a radial drag term. Red and orange curves highlight the equilibrium eccentricities of initial conditions undergoing both collisions and gravitational perturbations (assuming μ = 0.05 and R₀ = 115 km). Both differ in the assumed angular frequency ${\dot{\theta }}_1$ of M₁ around the center of mass of M_c. The red curve shows results assuming ${\dot{\theta }}_1$ equal to the keplerian mean-motion (n₁). Conversely, the orange curve was calculated considering a sub-keplerian orbital frequency equal to the spin rate of M₀, i.e. ${\dot{\theta }}_1={\mathrm{\Omega }}_0=0.46n_1$. For comparison, the black dashed curve shows the semi-secular equilibrium eccentricity e_ff, as given by equation (A.1).