A Dearth of Small Members in the Haumea Family Revealed by the OSSOS Survey

TL;DR

This study uses the OSSOS survey to identify small members of the Haumea family in the Kuiper belt, revealing a scarcity of small objects and suggesting a non-catastrophic formation process.

Contribution

It provides the first detection of small Haumea family members using OSSOS data, constraining the size distribution and proposing a graze-and-merge formation scenario.

Findings

Detected three Haumea family candidates with low ejection velocities.

The size distribution slope is shallow for objects larger than 20 km.

The family likely formed through a graze-and-merge event, not a catastrophic collision.

Abstract

While collisional families are common in the asteroid belt, only one is known in the Kuiper belt, linked to the dwarf planet Haumea. The characterization of Haumea's family helps to constrain its origin and, more generally, the collisional history of the Kuiper belt. However, the size distribution of the Haumea family is difficult to constrain from the known sample, which is affected by discovery biases. Here, we use the Outer Solar System Origins Survey (OSSOS) Ensemble to look for Haumea family members. In this OSSOS XVI study we report the detection of three candidates with small ejection velocities relative to the family formation centre. The largest discovery, 2013 UQ15, is conclusively a Haumea family member, with a low ejection velocity and neutral surface colours. Although the OSSOS Ensemble is sensitive to Haumea family members to a limiting absolute magnitude (Hr) of 9.5 (inferred diameter of ~90 km), the smallest candidate is significantly larger, Hr = 7.9. The Haumea family members larger than approximately 20 km in diameter must be characterized by a shallow H-distribution slope in order to produce only these three large detections. This shallow size distribution suggests that the family formed in a graze-and-merge scenario, not a catastrophic collision.