Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination

TL;DR

This paper reports the discovery of an extreme Trans-Neptunian Object with a highly inclined, elongated orbit, analyzes its dynamical behavior, and discusses implications for the Planet Nine hypothesis.

Contribution

It presents the discovery and detailed dynamical analysis of 2015 BP$_{519}$, the most extreme TNO known, and explores its relevance to Solar System models including Planet Nine.

Findings

2015 BP$_{519}$ has a semi-major axis of ~450 AU and inclination of ~54 degrees.

The object exhibits rapid diffusion in semi-major axis and constrained eccentricity and inclination variations.

Its orbit supports the potential existence of a distant massive perturber, like Planet Nine.

Abstract

We report the discovery and dynamical analysis of 2015 BP$_{519}$, an extreme Trans-Neptunian Object detected detected by the Dark Energy Survey at a heliocentric distance of 55 AU and absolute magnitude Hr= 4.3. The current orbit, determined from a 1110-day observational arc, has semi-major axis $a\approx$ 450 AU, eccentricity $e\approx$ 0.92 and inclination $i\approx$ 54 degrees. With these orbital elements, 2015 BP$_{519}$ is the most extreme TNO discovered to date, as quantified by the reduced Kozai action, which is is a conserved quantity at fixed semi-major axis $a$ for axisymmetric perturbations. We discuss the orbital stability and evolution of this object in the context of the known Solar System, and find that 2015 BP$_{519}$ displays rich dynamical behavior, including rapid diffusion in semi-major axis and more constrained variations in eccentricity and inclination. We also consider the long term orbital stability and evolutionary behavior within the context of the Planet Nine Hypothesis, and find that BP$_{519}$ adds to the circumstantial evidence for the existence of this proposed new member of the Solar System, as it would represent the first member of the population of high-i, $\varpi$-shepherded TNOs.