Julien Frouard

Since 2005 we know that asteroidal systems exist. They consist of tiny satellites (of size ~ 10 km), orbiting an often highly-elongated asteroid (~ 300 km). The dynamics exhibited by the satellites thus stand between those of binary asteroids, where all the components have similar masses, and those of satellites of planets, where the planet is an approximate spheroid and is much more massive than the satellites. Over long timescales, some types of resonances between the orbital frequencies found in the system can lead to serious instabilities of the orbits of the satellites, allowing them to collide with the asteroid, or to be ejected in heliocentric orbits. But these resonances cannot be attained without the help of dissipative effects, such as gravitational tides or infrared re-emission of the objects. These effects are the key to understand the long-term dynamics of these systems, and they highly depend on the material and the structure of the asteroid. I will review these aspects of the satellite dynamics and show the detailed study of (87) Sylvia and its satellites. I will then show how we can generalize this study to other asteroidal systems.