Time evolution of the orbital elements of the arc particles for the simulation shown in Fig. 8. Top: semi-major axis (km). For clarity, the semi-major axis of the first particle (resp. the third and fourth) has been shifted by − 10 (resp. by + 10 and + 20) km. The downward points are due to encounters with Galatea. Middle: mean longitudes (deg) with respect to satellite S₁. Bottom: eccentricity of the first particle, which exhibits stronger perturbations from close encounters with the co-orbital satellites, though it remains bound to the Adams ring region.