Identifying Collisional Families in the Kuiper Belt

Abstract

The identification and characterization of numerous collisional families-clusters of bodies with a common collisional origin-in the asteroid belt has added greatly to the understanding of asteroid belt formation and evolution. More recent study has also led to an appreciation of physical processes that had previously been neglected (e.g., the Yarkovsky effect). Collisions have certainly played an important role in the evolution of the Kuiper Belt as well, though only one collisional family has been identified in that region to date, around the dwarf planet Haumea. In this paper, we combine insights into collisional families from numerical simulations with the current observational constraints on the dynamical structure of the Kuiper Belt to investigate the ideal sizes and locations for identifying collisional families. We find that larger progenitors (r ∼ 500 km) result in more easily identifiable families, given the difficulty in identifying fragments of smaller progenitors in magnitude-limited surveys, despite their larger spread and less frequent occurrence. However, even these families do not stand out well from the background. Identifying families as statistical overdensities is much easier than characterizing families by distinguishing individual members from interlopers. Such identification seems promising, provided the background population is well known. In either case, families will also be much easier to study where the background population is small, i.e., at high inclinations. Overall, our results indicate that entirely different techniques for identifying families will be needed for the Kuiper Belt, and we provide some suggestions.

On the genesis of the Haumea system

“…The sum of the volumes of all these objects provides an estimation of 430 km for the minimum diameter of the family parent body. Campo Bagatin & Benavidez (2012) and Marcus et al (2011) find that this is right in the upper limit for likely shattering of large bodies in the EKB. ALICANDEP predicts the existence of at most one single family with such a large parent body, after the LHB period.…”

Characterisation of candidate members of (136108) Haumea’s family

“…The clustering of Haumea's family, with a low δv between fragments, may be its most peculiar property (Marcus et al 2011), and can be used as a strong constraint on formation models. Additionally, the models must explain the spin of Haumea and the mass and velocity dispersion of its fragments, keeping in mind that some of the original mass has been lost over time (TNO region is thought to be far less populous today than it was in the early solar system, see, e.g., Morbidelli et al 2008).…”

The dynamical evolution of dwarf planet (136108) Haumea’s collisional family: general properties and implications for the trans-Neptunian belt

“…On the other hand, other studies suggest that TNOs that lack strong water ice features in their spectra could still be dynamically tied to the family, meaning that a number of new large members may await identification (Benecchi et al 2011). Interestingly, new techniques for family identification based on statistical analysis of groups of objects compared to the background population have become available and do not require knowledge of surface properties such as colours or spectra (Marcus et al 2011). This suggests that it is possible to identify both the currently known Haumean family and new members purely on theoretical grounds.…”