Circumbinary Chaos: Using Pluto's Newest Moon to Constrain the Masses of Nix & Hydra

Abstract

The Pluto system provides a unique local laboratory for the study of binaries with multiple low mass companions. In this paper, we study the orbital stability of P4, the most recently discovered moon in the Pluto system. This newfound companion orbits near the plane of the Pluto-Charon binary, roughly halfway between the two minor moons Nix and Hydra. We use a suite of few body integrations to constrain the masses of Nix and Hydra, and the orbital parameters of P4. For the system to remain stable over the age of the Solar System, the masses of Nix and Hydra likely do not exceed 5e16 kg and 9e16 kg, respectively. These upper limits assume a fixed mass ratio between Nix and Hydra at the value implied by their median optical brightness. Our study finds that stability is more sensitive to their total mass and that a downward revision of Charon's eccentricity (from our adopted value of 0.0035) is unlikely to significantly affect our conclusions. Our upper limits are an order of magnitude below existing astrometric limits on the masses of Nix and Hydra. For a density at least that of ice, the albedos of Nix and Hydra would exceed 0.3. This constraint implies they are icy, as predicted by giant impact models. Even with these low masses, P4 only remains stable if its eccentricity e < 0.02. The 5:1 commensurability with Charon is particularly unstable, Combining stability constraints with the observed mean motion places the preferred orbit for P4 just exterior to the 5:1 resonance. These predictions will be tested when the New Horizons satellite visits Pluto. Based on the results for the Pluto-Charon system, we expect that circumbinary, multi-planet systems will be more widely spaced than their singleton counterparts. Further, circumbinary exoplanets close to the three-body stability boundary, such as those found by Kepler, are less likely to have other companions nearby.

12 pages, 7 figures

References in corpus (6)

• The Transiting Circumbinary Planets Kepler-34 and Kepler-35
• The New Horizons Pluto Kuiper belt Mission: An Overview with Historical Context
• The Correlated Colors of Transneptunian Binaries
• New Horizons: Anticipated Scientific Investigations at the Pluto System
• Masses of Nix and Hydra
• Ejecta Exchange, Color Evolution in the Pluto System, and Implications for KBOs and Asteroids with Satellites

Cited by in corpus (26)

• Kepler-47: A Transiting Circumbinary Multi-Planet System
• The Small Satellites of Pluto as Observed by New Horizons
• The Pluto System After New Horizons
• Planet Scattering Around Binaries: Ejections, Not Collisions
• The Formation of Pluto's Low Mass Satellites
• Orbital Stability of Multi-Planet Systems: Behavior at High Masses
• Terrestrial planet formation: Dynamical shake-up and the low mass of Mars
• Planet Packing in Circumbinary Systems
• Instabilities in Multi-Planet Circumbinary Systems
• On the Origin of Pluto's Small Satellites by Resonant Transport
• Dynamical capture in the Pluto-Charon system
• The New Horizons and Hubble Space Telescope Search For Rings, Dust, and Debris in the Pluto-Charon System
• 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
• A Pluto-Charon Concerto: An Impact on Charon as the Origin of the Small Satellites
• Ejecta Transfer in the Pluto System
• Past and present dynamics of the circumbinary moons in the Pluto-Charon system
• A Dynamical Systems Approach to the Theory of Circumbinary Orbits in the Circular Restricted Problem
• On the existence of regular and irregular outer moons orbiting the Pluto-Charon system
• Evolution of a ring around the Pluto-Charon binary
• On the Estimation of Circumbinary Orbital Properties
• Recent Kepler Results On Circumbinary Planets
• A Pluto--Charon Concerto II. Formation of a Circumbinary Disk of Debris After the Giant Impact
• A Deep Search for Additional Satellites around the Dwarf Planet Haumea
• Orbit determination of the moons of the Pluto-Charon system
• A Pluto--Charon Sonata IV. Improved Constraints on the Dynamical Behavior and Masses of the Small Satellites