HALF-BROTHERS IN THE SCHULHOF FAMILY?

Disruptive collisions in the asteroid belt produced groups of fragments known as the asteroid families. The studies of identified asteroid families help us to better understand issues related to impact physics, space weathering, asteroid interior, and collisional evolution of the main belt. Here, we analyze a family near the central main belt asteroid (2384) Schulhof. We show that the previously found group of objects around (81337) 2000 GP36 is actually a sub-cluster in the larger Schulhof family. Using backward integrations we demonstrate that the orbits of sub-cluster asteroids converge to that of (2384) Schulhof at 780±100 kyr ago, suggesting that the breakup event happened very recently. Interestingly, a similar analysis of the two newly discovered members of the Schulhof family may indicate a second event 100 kyr ago (e.g., secondary collision, fission, satellite instability). If confirmed, the formation history of the Schulhof family would suggest that small asteroids may have very colorful lifetimes. Additional astrometric observations of the two new member asteroids will be needed to improve their present orbit and better constrain their past histories. Key words: minor planets, asteroids: general 1