Gravitational study of escape routes and residence regions of Ceres and Vesta fragments

Abstract

Aims. Ceres and Vesta are the two largest bodies in the main asteroid belt (MB) and have been extensively studied, particularly since the DAWN mission. Vesta is known to have an associated asteroid family, while the existence of a Ceres family is uncertain. This study investigates the fate of multi-kilometre fragments ejected from Ceres and Vesta due to impacts over a timescale of several hundred million years. Methods. We performed purely gravitational N-body simulations to investigate the dynamical evolution of multi-kilometre-sized fragments ejected from Ceres and Vesta. We tracked the trajectories of these fragments and identified their residence regions within the MB. We analysed the escape routes and end states of the fragments that manage to leave the MB, including the delivery to the near-Earth asteroids (NEAs). We also estimated the number of collisions with Earth that could be attributed to large fragments ejected from Ceres and Vesta. Results. Our simulations show that the Ceres fragments are dispersed over a larger region in the MB compared to Vesta fragments due to their higher ejection velocities. We identified the escape routes of the fragments that leave the MB, which for the Ceres fragments are the 5:2 and 8:3 mean-motion resonances (MMR), and for the Vesta fragments are the 3:1 MMR and ν6 secular resonance, where they can be delivered to the NEA region. We also find that the Pristine region, located between the 5:2 and 7:3 MMR, is the most likely place to find any surviving member of a Ceres family. There were no collisions of large Ceres or Vesta fragments with Earth over the age of the Solar System, suggesting that, under the model considered here, the howardite–eucrite–diogenite meteorites originate from smaller NEAs from Vesta.