LiDO: Discovery of a 10:1 Resonator with a Novel Libration State

The Large inclination Distant Objects LiDO survey has discovered the first securely classified object in the 10:1 mean motion resonance of Neptune. This object, 2020 VN40, is short-term stable in the 10:1 resonance, but not stable on Gyr timescales. 2020 VN40 is likely part of the scattering sticking population, and temporarily resides in the 10:1 resonance at ~139.5 au. This discovery confirms that this distant resonance is populated, as a single detection is likely to be indicative of a large population that is difficult to detect due to observational biases. This object has an inclination of 33.4 degrees, and n-body integrations of orbital clones of 2020 VN40 have revealed some unexpected evolutions. While clones of 2020 VN40 show resonant libration around the expected resonance centers of approximately 90, 180, and 270 degrees, for a restricted range of inclination and eccentricity values some clones librate around a resonant argument of 0 degrees. As this occurs for the slightly lower-eccentricity portions of the evolution, this behavior can also be quite stable. Our initial exploration suggests that this libration around a center of 0 degrees is a generic effect for highly inclined objects in n:1 resonances because the nature of their resonant interaction with Neptune becomes a strong function of their argument of pericenter, omega. At large inclination, the resonant islands shift as omega precesses, switching the center of symmetric libration to 0 degrees for omega=90 degrees and omega=270 degrees. 2020 VN40 provides interesting insight into the evolution of the large-inclination resonators, which become more common at increasing semi-major axis.