Beyond Point Masses: Survey of Detected Non-Keplerian Effects in TNO Binaries

The mutual orbits of Trans-Neptunian Binaries (TNBs) provide powerful insight into the formation and evolution of the outer solar system. The orbital properties of individual TNB systems provide insight into those objects’ histories, while the ensemble of TNB orbits informs models of planetesimal formation. Previous investigations into TNB orbits have assumed the binary components follow Keplerian orbits. While all TNBs will eventually exhibit non-Keplerian motion because of their aspherical shapes, it has been unclear whether and when these effects are detectable with current data. Our newly-developed and publicly-available code MultiMoon uses Bayesian parameter inference to fit TNB relative astrometry to detect or constrain non-Keplerian parameters. In an effort to identify the best candidates for detection of non-Keplerian motion, we have used MultiMoon to complete a series of exploratory non-Keplerian fits for every TNB. Here, we present our result that non-Keplerian effects are common among TNB systems at a variety of sizes and separations.