Abstract

We describe the discovery of 2015 BP519, an extreme trans-Neptunian object in our solar system detected by the Dark Energy Survey. Its current orbit, with a semi-major axis of roughly 450 AU and an inclination of 54 degrees, places it as the most extreme TNO discovered to date. 2015 BP519 displays rich dynamical behavior due to its interactions with the four known giant planets, including rapid diffusion in semi-major axis, but its inclination is expected to remain confined to its current value in the known solar system. We also discuss the BP519’s behavior within the context of the Planet Nine hypothesis and find that 2015 BP519 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, ϖ-shepherded TNOs.