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A dearth of small members in the Haumea family revealed by OSSOS

2019; Nature Portfolio; Volume: 4; Issue: 1 Linguagem: Inglês

10.1038/s41550-019-0867-z

2397-3366

Rosemary E. Pike, Benjamin C. N. Proudfoot, Darin Ragozzine, Mike Alexandersen, Steven Maggard, Michele T. Bannister, Ying-Tung Chen, Brett Gladman, J. J. Kavelaars, Stephen Gwyn, Kathryn Volk,

Stellar, planetary, and galactic studies

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 ≃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. An extensive survey to search for members of the only known Kuiper belt family, named after the parent body Haumea, found no family members fainter than absolute magnitude Hr = 7.9, significantly brighter than the detection limit (Hr = 9.5). This lack of small members is inconsistent with a catastrophic disruption as the origin of the Haumea family.