The stability around Chariklo and the confinement of its rings

Abstract

Context. Chariklo has two narrow and dense rings, C1R and C2R, located at 391 km and 405 km, respectively. Aims. In the light of new stellar occultation data, we study the stability around Chariklo. We also analyse three confinement mechanisms that prevent the spreading of the rings, based on shepherd satellites in resonance with the edges of the rings. Methods. This study was performed through a set of numerical simulations and the Poincaré surface of section technique. Results. From the numerical simulation results, and from the current parameters referring to the shape of Chariklo, we verify that the inner edge of the stable region is much closer to Chariklo than the rings. The Poincaré surface of sections allows us to identify periodic and quasi-periodic orbits of the first kind, and also the resonant islands corresponding to the 1:2, 2:5, and 1:3 resonances. We construct a map of aeq versus eeq space that gives the location and width of the stable region and the 1:2, 2:5, and 1:3 resonances. Conclusions. We find that the first kind periodic orbit family can be responsible for a stable region whose location and size meet that of C1R, for specific values of the ring particle eccentricities. However, C2R is located in an unstable region if the width of the ring is assumed to be about 120 m. After analysing different systems, we propose that the best confinement mechanism is composed of three satellites: two satellites shepherding the inner edge of C1R and the outer edge of C2R, and the third satellite trapped in the 1:3 resonance.