A dwarf planet class object in the 21:5 resonance with Neptune

TL;DR

This paper reports the discovery and detailed orbital analysis of a new dwarf planet candidate in the 21:5 resonance with Neptune, highlighting its implications for understanding the trans-Neptunian population.

Contribution

It presents the discovery of a new dwarf planet candidate with well-determined orbit, confirming its resonance with Neptune and discussing its significance for trans-Neptunian dynamics.

Findings

2010 JO179 is a dwarf planet candidate with a diameter of 600-900 km.

It is in a secure 21:5 mean-motion resonance with Neptune.

The orbit is precisely determined over a decade of observations.

Abstract

We report the discovery of a $H_r = 3.4\pm0.1$ dwarf planet candidate by the Pan-STARRS Outer Solar System Survey. 2010 JO$_{179}$ is red with $(g-r)=0.88 \pm 0.21$, roughly round, and slowly rotating, with a period of $30.6$ hr. Estimates of its albedo imply a diameter of 600--900~km. Observations sampling the span between 2005--2016 provide an exceptionally well-determined orbit for 2010 JO$_{179}$, with a semi-major axis of $78.307\pm0.009$ au, distant orbits known to this precision are rare. We find that 2010 JO$_{179}$ librates securely within the 21:5 mean-motion resonance with Neptune on hundred-megayear time scales, joining the small but growing set of known distant dwarf planets on metastable resonant orbits. These imply a substantial trans-Neptunian population that shifts between stability in high-order resonances, the detached population, and the eroding population of the scattering disk.