Dynamical portrait of the Lixiaohua asteroid family

Abstract

In this paper we present a comprehensive analysis of the dynamics in the region of the (3556) Lixiaohua asteroid family. The family lies in a particularly interesting region of the phase space, crossed by several two-body and three-body mean motion resonances. Also, members of this family can have close encounters with large asteroids, such as Ceres. We have identified the mean motion resonances which contribute to the long-term dynamical evolution of the family and our results confirm that the members of this family can be classified into a number of groups, exhibiting different dynamical behavior. We show for the first time that in the Lixiaohua region, apart from the chaotic diffusion in proper eccentricity and inclination (ep and Ip), there is at least one extended chaotic zone where several resonances overlap, thus giving rise to chaotic diffusion in proper semi-major axis (ap) as well. Using a code of Monte Carlo type, we simulate the evolution of the family, according to the model which combines the chaotic diffusion (in ap, ep and Ip), Yarkovsky/YORP thermal effect and random walk in ap due to the close encounters with massive asteroids. These simulations show that all these effects should be taken into account in order to accurately explain the observed distribution of family members in the space of proper elements, although a "minimal" model that accounts for chaotic diffusion in (ep, Ip), Yarkovsky-induced drift in ap and random walk in ap due to the close encounters with the most massive asteroids is enough to grossly characterize the shape of the family. © 2010 Springer Science+Business Media B.V.