Alessandro Morbidelli

Chaire Chaire Formation planétaire : de la Terre aux exoplanètes

Collège de France

Année 2025-2026

David Nesvorný

Conférence - David Nesvorný : Collisional Families in the Asteroid Belt and Sources of Meteorites

David Nesvorný

Southwest Research Institute, USA

Résumé

Main-belt asteroids originally formed in a dynamically quiet disk, but their orbits were later stirred by Jupiter's gravity, leading to high-speed collisions. Over the age of the Solar System, dozens of large asteroids have been disrupted by such impacts, producing groups of fragments known as asteroid families. Here we explain how asteroid families are identified, review the current inventory, and discuss how they provide insight into the collisional and dynamical evolution of the asteroid belt. Currently, about 360 asteroid families have been cataloged, including ~100 that formed within the past 10 million years. Studies of these families shed light on the physics of large-scale collisions - a key process in the formation of Earth and other terrestrial planets - and place important constraints on the belt's collisional history. Some findings suggest that much of the asteroid belt may be composed of fragments from early, unresolved breakups. Asteroid families also play a crucial role in understanding orbital evolution, including the influence of radiative forces like the Yarkovsky and YORP effects, as well as resonant interactions - processes that underpin the delivery of near-Earth asteroids and meteorites.