Evolution of a ring around the Pluto-Charon binary

Abstract

We consider the formation of satellites around the Pluto-Charon binary. An early collision between the two partners likely produced the binary and a narrow ring of debris, out of which arose the moons Styx, Nix, Kerberos and Hydra. How the satellites emerged from the compact ring is uncertain. Here we show that a particle ring spreads from physical collisions and collective gravitational scattering, similar to migration. Around a binary, these processes take place in the reference frames of "most circular" orbits, akin to circular ones in a Keplerian potential. Ring particles damp to these orbits and avoid destructive collisions. Damping and diffusion also help particles survive dynamical instabilities driven by resonances with the binary. In some situations, particles become trapped near resonances that sweep outward with the tidal evolution of the Pluto-Charon binary. With simple models and numerical experiments, we show how the Pluto-Charon impact ring may have expanded into a broad disk, out of which grew the circumbinary moons. In some scenarios, the ring can spread well beyond the orbit of Hydra, the most distant moon, to form a handful of smaller satellites. If these small moons exist, New Horizons will find them.

44 pages of text, 10 figures, ApJ, accepted. (In this version, Section 2 and Figure 1 are new, outlining our approach to the problem of satellite formation around the Pluto-Charon binary.)

References in corpus (13)

• The Transiting Circumbinary Planets Kepler-34 and Kepler-35
• The New Horizons Pluto Kuiper belt Mission: An Overview with Historical Context
• High Albedos of Low Inclination Classical Kuiper Belt Objects
• Terrestrial Planet Formation Surrounding Close Binary Stars
• A Hybrid N-body--Coagulation Code for Planet Formation
• Long-term & large-scale viscous evolution of dense planetary rings
• On the migration of protoplanets embedded in circumbinary disks
• Masses of Nix and Hydra
• Analytic orbit propagation for transiting circumbinary planets
• Charon's radius and density from the combined data sets of the 2005 July 11 occultation
• Geometrical and Physical Properties of Circumbinary Discs in Eccentric Stellar Binaries
• Fomalhaut b as a Cloud of Dust: Testing Aspects of Planet Formation Theory
• On the Origin of Pluto's Small Satellites by Resonant Transport

Cited by in corpus (8)

• The Pluto System After New Horizons
• The Short Rotation Period of Hi'iaka, Haumea's Largest Satellite
• A Pluto-Charon Sonata: The Dynamical Architecture of the Circumbinary Satellite System
• A Pluto--Charon Sonata: Dynamical Limits on the Masses of the Small Satellites
• On the existence of regular and irregular outer moons orbiting the Pluto-Charon system
• A Pluto--Charon Concerto II. Formation of a Circumbinary Disk of Debris After the Giant Impact
• A Pluto-Charon Sonata III. Growth of Charon from a Circum-Pluto Ring of Debris
• A Pluto--Charon Sonata IV. Improved Constraints on the Dynamical Behavior and Masses of the Small Satellites