Presentation #410.08 in the session Dynamical Interactions in the Kuiper Belt (iPosters).
Cold Classical Trans-Neptunian Objects (CCTNOs) are thought to have been formed in situ by the streaming instability. Most of the largest CCTNOs are known binaries whose physical and orbital properties can constrain formation models. Sila-Nunam is particularly interesting as a tidally-locked double-synchronous system with detected mutual events similar to Pluto-Charon. We have performed detailed investigations of the orbits of CCTNO Binaries Sila-Nunam and Borasisi-Pabu using MultiMoon, our code for Bayesian parameter inference of binary relative astrometry, to infer non-Keplerian orbits. MultiMoon has revealed statistically significant non-Keplerian motion for both of these objects. We infer the gravitational quadrupole harmonics J2 and C22 for these objects as well as information on the spin-orbit orientation. We compare the implied shapes to the previously estimated shapes of these objects from lightcurves. We will comment on the implications of our results on the formation of these CCTNOs.