Different arrival times of CM- and CI-like bodies from the outer Solar System in the asteroid belt

Abstract

Understanding the birthplace of meteoritic materials is critical for reconstructing the early Solar System and contextualizing recent sample-return missions. Here, we use N-body simulations to investigate the influence of giant-planet growth and inward type I migration on the delivery of outer Solar System bodies to the asteroid belt. We find that the radial distribution of planetesimals reflects that of the gas in the disk at the moment of implantation. Since chondrule-rich CM- and chondrule-poor CI-like bodies with diameters greater than 100 km have different radial distributions, they must have been implanted at different times. CM-like bodies probably originate from the Saturn formation region and were implanted by aerodynamic drag into the belt during Saturn’s growth phase, while CI- and comet-like bodies probably formed in the primordial trans-Uranian disk and were scattered inwards by the formation and migration of Uranus and Neptune driven by remaining planetesimals. Our results support a formation zone for chondrules interior to the ice giants (≤10 au), and suggest that CM-like bodies contributed to the water budget of the telluric planets.