The effect of orbital evolution on the Haumea (2003 EL61) collisional family

TL;DR

This study uses numerical simulations to estimate the age and dynamical evolution of the Haumea collisional family in the Kuiper belt, assessing how its population and clustering are preserved over billions of years.

Contribution

It provides the first long-term dynamical evolution analysis of the Haumea family, estimating its minimum age and loss rates, and compares formation models with observational data.

Findings

The Haumea family is at least 1 Gyr old with 95% confidence.

Approximately 20-45% of family members are lost to Neptune encounters over 3.5 Gyr.

Current observations are consistent with formation models, but more objects at higher velocities are expected.

Abstract

The Haumea family is currently the only identified collisional family in the Kuiper belt. We numerically simulate the long-term dynamical evolution of the family to estimate a lower limit of the family's age and to assess how the population of the family and its dynamical clustering are preserved over Gyr timescales. We find that the family is not younger than 100 Myr, and its age is at least 1 Gyr with 95% confidence. We find that for initial velocity dispersions of 50-400 m/s, approximately 20-45% of the family members are lost to close encounters with Neptune after 3.5 Gyr of orbital evolution. We apply these loss rates to two proposed models for the formation of the Haumea family, a graze-and-merge type collision between two similarly sized, differentiated KBOs or the collisional disruption of a satellite orbiting Haumea. For the graze-and-merge collision model, we calculate that >85% of the expected mass in surviving family members within 150 m/s of the collision has been identified, but that one to two times the mass of the known family members remains to be identified at larger velocities. For the satellite-break-up model, we estimate that the currently identified family members account for ~50% of the expected mass of the family. Taking observational incompleteness into account, the observed number of Haumea family members is consistent with either formation scenario at the 1 sigma level, however both models predict more objects at larger relative velocities (>150 m/s) than have been identified.