Evolution of the eccentricity and inclination of Ariel during the capture into the 2:1 mean motion resonance with Umbriel, considering different values of the parameter Q₂ (k_2,2 = 0.15). The dotted line represents the eccentricity threshold (see text) above which the inclination resonance is triggered. These simulations were obtained setting t_α,2 = 2.3 Gyr and initial semimajor axes a₂ = 6.150 R_U and a₃ = 9.841 R_U.