Responses of test particles to the first-order 2/3 and second-order 1/3 SORs. Left column: symbols represent the maximum eccentricities e_max reached by particles initially on circular orbits for three values of the mass anomaly µ, near the 2/3 SOR (upper panel) and the 1/3 SOR (lower panel). The gray dashed curves are the analytical estimates of e_max displayed in Figs. 3 and 4 of Paper I. The points are plotted against the normalized distance to the resonance, Δa/W_res = (ā − a₀)/W_res, where a₀ is the radius of the circular orbit at exact resonance, ā is the modified semimajor axis (Eq. (2)), and W_res is the width of the resonance (Eq. (3)). Right column: same, but with the timescales of T_res necessary to reach the maximum eccentricities e_max. This figure shows that our numerical integrations reproduce satisfactorily the calculated distribution of e_max, as well as the µ-scaling expected from Eqs. (3) and (4).