Close TNO Passages as a Driver of the Origin and Evolution of Ultra-Wide Kuiper Belt Binaries

• Main Authors: Campbell, Hunter M, Stone, Lukas R, Kaib, Nathan A
• Format: Journal Article
• Language: English
• Published: 11-11-2022
• Subjects: Physics - Earth and Planetary Astrophysics
• DOI: 10.48550/arxiv.2211.06383

Within the dynamically cold low inclination portion of the Classical Kuiper
Belt, there exists a population of weakly bound binary systems with a number of
unusual properties; most notable of which is their extremely wide orbital
separations; beyond 7% of their Hill radii. The stability and evolution of
these Ultra-Wide Trans-Neptunian Binaries (TNBs) have, in the past, been
studied extensively under the assumption that the primary evolving mechanisms
are interactions between the binary components and impacting Trans-Neptunian
Objects (TNOs). Here, we instead study their evolution as driven by the
gravitational perturbations of close passing but non-impacting TNOs. By
simulating these passages, we show that the aggregate effects of encounters
over billions of years have a significant effect on Kuiper Belt binary
evolution. Such processes can lead to tight binaries widening significantly
over time, approaching and sometimes surpassing the separation of the widest
known TNBs. We also find that the eccentricity and inclination distributions of
observed Ultra-Wide TNBs can be sampled from such widened binaries. While we
are unable to produce enough wide binaries to explain their abundance, the
orbital properties of ones we do produce are consistent with known wide
binaries.