Stability of coorbital objects around the Pluto-Charon binary

Abstract:

The Pluto-Charon binary system is dynamical interesting with its retinue of four small moons. The system is relatively full with few remaining stable locations evenly-spaced for additional moons on uninclined, circular orbits; most of these are Trojan (Tadpole/Horseshoe) orbits (Pires et al. 2011; Porter and Stern 2015).

In this work, we study the coorbital region of each moon with long time integrations taking into account the gravitational effects of the satellites Charon, Styx, Nix, Kerberos and Hydra. We numerically simulate a sample of 10,000 test particles initially located randomly around each moon's orbit (Figure). All test particles start on nearly circular and uninclined orbits and are followed for 5000 years. The results of our numerical simulations show stable coorbital objects – both Tadpoles and Horseshoes – for each of the small moons (Table). Horseshoe orbits are most common at all moons, although Hydra also has a sizeable population of Tadpole orbits. We also find interesting cases where the orbits switch from L₄ Tadpoles to Horseshoes and even to L₅ Tadpoles. These transitioning orbits comprise less than 1% of coorbital objects at all moons, and are most common at Styx. We have also investigated eccentric and inclined orbits and will report on our findings.