Asteroid Mass Estimation by Mutual Perturbations During Close Encounters After Gaia Focused Product Release

Abstract Mutual perturbations between asteroids during close encounters allow the estimation of their masses using precise astrometric observations. We use all astrometry reported to the Minor Planet Center, high-precision astrometry from ESA’s Gaia Focused Product Release, and radar delay-Doppler data when available. A search for close encounters between all known asteroids and a preliminary list of the largest asteroids leads to approximately 975,000 asteroids that may have been perturbed in a measurable way. We find about 86,000 asteroids with signal in their astrometry for one or more asteroid masses. The multidimensional, weighted combination of all estimates yields 77 asteroid masses with signal-to-noise ratio (SNR) > 10, and 232 asteroid masses with SNR > 3, all in the main belt or outer main belt. We did not find any signal for individual masses of Trojans, Centaurs, or Trans-Neptunian Objects. From the estimated asteroid masses, we derive updated density estimates for asteroids with well-determined diameters. The updated total main belt mass estimate (sum of all a < 4.6 au, H < 18) is (13.11 ± 0.06) × 10 −10 M ⊙ .