Assessment of different formation scenarios for the ring system of (10199) Chariklo

Abstract

Context. The discovery that the Centaur (10199) Chariklo possesses a ring system opens questions about their origin. Aims. We here asses the plausibility of different scenarios for the origin of the observed ring system. Methods. We first consider the possibility that the material of the ring originated in the disruption of a satellite that had reached a critical distance from the Centaur. We discuss the conditions for the putative satellite to approach the Centaur as a consequence of tidal interaction. A three-body encounter is also considered as a transport mechanism. In addition, we study the case in which the ring is formed by the ejecta of a cratering collision on the Centaur and we constrain the collision parameters and the size of the resulting crater of the event. Finally, we consider that the ring material originates from a catastrophic collision between a background object and a satellite located at a distance corresponding to the current location of the ring. We compute the typical timescales for these scenarios. Results. We estimate that in order to be tidally disrupted a satellite would have had to be larger than approximately 6.5 km at the location of the rings. However the tidal interaction is rather weak for objects of the size of outer solar system bodies at the ring location, therefore we considered other more effective mechanisms by which a satellite might have approached the Centaur. Collisonal scenarios are both physically plausible for the formation, but semianalytical estimations indicate that the probability of the corresponding collisions is low under current conditions.