The dynamical structure of a hypothetical disc of particles around the asteroid 99942 Apophis

Abstract

The asteroid 99942 Apophis is a Near Earth Asteroid, which was just recently removed from the Potentially Hazardous Asteroids list, since there is no risk of collision with the Earth for the next 100 years. Although, its importance to dynamical astronomy remains evidenced due to other further close encounters that will happen. In the current work, we analyze the dynamics of a hypothetical disc with massless particles around Apophis that produce a complex structure in terms of possible fates (survivors, collisions, and ejections). The gravitational potential due to the highly irregular shape of Apophis produces asymmetries in the dynamics around it. Commensurabilities between the particle’s orbital motion frequencies and Apophis’ spin generate resonances that dominate the observed complex structure. The results show that the orbital evolution in the third dimension is affected by a combination of the resonances and the gravitational field elongated asymmetry, which helps explain most structure details.