A Non-Primordial Origin for the Widest Binaries in the Kuiper Belt

Abstract

Nearly one-third of objects occupying the most circular, coplanar Kuiper belt orbits (the cold classical belt) are binary, and several percent of them are "ultra-wide" binaries (UWBs): 100-km-sized companions spaced by tens of thousands of km. UWBs are dynamically fragile, and their existence is thought to constrain early Solar System processes and conditions. However, we demonstrate that UWBs can instead attain their wide architectures well after the Solar System's earliest epochs, when Neptune's orbital migration implants the modern non-cold, or "dynamic", Kuiper belt population. During this implantation, cold classical belt binaries are likely to have close encounters with many planetesimals scattered across the region, which can efficiently dissociate any existing UWBs and widen a small fraction of tighter binaries into UWB-like arrangements. Thus, today's UWBs may not be primordial and cannot be used to constrain the early Solar System as directly as previously surmised.

27 pages, 12 figures

References in corpus (7)

• Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune
• Evidence for Two Populations of Classical Transneptunian Objects: The Strong Inclination Dependence of Classical Binaries
• Tracking Neptune's Migration History through High-Perihelion Resonant Trans-Neptunian Objects
• Collision Probabilities in the Edgeworth-Kuiper belt
• Close TNO Passages as a Driver of the Origin and Evolution of Ultra-Wide Kuiper Belt Binaries
• Evolution of Primordial Kuiper Belt Binaries Through a Giant Planet Instability
• Signatures of a Distant Planet on the Inclination Distribution of the Detached Kuiper Belt

Cited by in corpus (1)

• Considering contact forces during the formation of planetesimals by gravitational collapse: mutual orbits, spin states, and shapes