New Candidates for Recent Asteroid Breakups

Asteroids in our solar system formed in a dynamically quiescent disk, but their orbits became gravitationally stirred enough by Jupiter to lead to high-speed collisions. As a result, several dozen large asteroids have been disrupted by impacts over the past several gigayears and have produced groups of fragments called asteroid families. Here we re-port three new candidates for asteroid families that were formed by collisions occurring in the last 1Myr. According to our modeling of the past orbital histories of known cluster members, we estimate that the Emilkowalski, 1992 YC2, and Lucascavin clusters are 220 30, 50Y250, and 300Y800 kyr old, respectively. Together with the previously iden-tified Datura cluster, estimated to be 450 50 kyr old, they are the most recent asteroid breakups ever discovered in the main belt. Astronomical observations of identified familymembers can be used to better understand impact physics, asteroid composition, and surface-aging processes. Discovered breakups may also be important sources of inter-planetary dust. Key words: minor planets, asteroids 1.