title: Asteroid families: observational evidence for common origins.
abstract: Colors of minor planets in the UBV system indicate compositions quite distinct from those of the field population in each of three Hirayama families. The Eos and Koronis families apparently originated from the collisional fragmentation of undifferentiated silicate bodies, and the Nysa group from a geochemically differentiated parent body.
authors.forename: J
authors.initials: J
authors.lastname: Gradie
authors.forename: B
authors.initials: B
authors.lastname: Zellner