Portrait of Theobalda as a young asteroid family

Abstract

The (778) Theobalda asteroid family has attracted little attention so far, but in our study we show that it is important in several ways. In this paper, we investigate the origin and evolution of the Theobalda family. First, we identify the family as a statistically relevant group in the space of synthetic proper elements. Using the hierarchical clustering method and the adopted cut-off velocity of dcut-off= 85 ms-1, we have found that the Theobalda family currently consists of 128 members. This family is located in the outer belt, near the proper semimajor axis ap≈ 3.175 au. This region is crossed by several three-body mean motion resonances, which give rise to significant chaotic zones. Consequently, the majority of family members reside on chaotic orbits. Using two independent methods, chaotic chronology and backward integration, we have found the Theobalda family to be only 6.9 ± 2.3 Myr old. We have also estimated that the family was likely produced by the cratering impact on a parent body of diameter DPB≈ 78 ± 9 km. © 2010 The Author. Journal compilation © 2010 RAS.