A population of main belt asteroids co-orbiting with Ceres and Vesta

TL;DR

This study identifies and analyzes a population of main belt asteroids co-orbiting with Ceres and Vesta, revealing their transient nature, stability factors, and potential for quasi-satellite states, with implications for asteroid dynamics and detection.

Contribution

The paper improves search criteria and provides the first comprehensive analysis of co-orbital asteroids with Ceres and Vesta, including their population size, stability, and dynamical behavior.

Findings

Approximately 51 co-orbitals with Ceres and 44 with Vesta identified.

Co-orbital episodes last from hundreds of thousands to over two million years.

Existence of quasi-satellite orbiters around Ceres and Vesta demonstrated.

Abstract

We have carried out a search for Main Belt Asteroids (MBAs) co-orbiting with the large MBA Vesta and the dwarf planet Ceres. Through improving the search criteria used in (Christou, 2000b) and numerical integrations of candidate coorbitals, we have identified approximately 51 (44) objects currently in co-orbital libration with Ceres (Vesta). We show that these form part of a larger population of transient coorbitals; 129 (94) MBAs undergo episodes of co-orbital libration with Ceres (Vesta) within a 2 Myr interval centred on the present. The lifetime in the resonance is typically a few times 10^5 yr butcan exceed 2*10^6 yr. The variational properties of the orbits of several co-orbitals were examined. It was found that their present states with respect to the secondary are well determined but knowledge of it is lost typically after ~2*10^5 years. Objects initially deeper into the coorbital region maintain their coorbital state for longer. Using the model of Namouni et al. (1999) we show that their dynamics are similar to those of temporary coorbital NEAs of the Earth and Venus. As in that case, the lifetime of resonant libration is dictated by planetary secular perturbations, the inherent chaoticity of the orbits and close encounters with massive objects other than the secondary. In particular we present evidence that, while in the coorbital state, close encounters with the secondary are generally avoided and that Ceres affects the stability of tadpole librators of Vesta. Finally we demonstrate the existence of Quasi-satellite orbiters of both Ceres and Vesta and conclude that decametre-sized objects detected in the vicinity of Vesta by the DAWN mission may, in fact, belong to this dynamical class rather than be bona-fide (i.e. keplerian) satellites of Vesta.