Asteroid pairs have been discovered in the main belt and Hungaria small body populations. These objects are of major interest, as they inform us about dynamic processes related to their lifetime. To date, no asteroid pairs have been found in the Jovian Trojans, despite the presence of several binaries and collisional families in the population. At the same time, this population is particularly important in our understanding of the beginning of the Solar system, having been formed in the trans-Neptunian zone and only later captured around the Jupiter Lagrange points. Here we report the discovery of the first pair, 258656 and 2013 CC41, in the Jovian Trojan population. A couple of approximately equal size bodies, diameters ≃ 7.7 km and ≃ 6.7 km, is located very close to the L4 Lagrange point. Not only this location helps to increase the statistical significance of the pair, but it also facilitates attempts in determining past orbital convergence of their orbits. Using numerical integrations, including Yarkovsky clones, we find the pair is at least approximately 380 Myr old, but its age may also be several Gyrs. The existence of the 258656-2013 CC41 implies there should be many more of them in the Trojan population. Our preferred formation mechanism is a split of a formerly binary system, but rotation fission driven by YORP torques may not be excluded too.
AAS/Division of Dynamical Astronomy Meeting
- Pub Date:
- August 2020