CFHT UM2019 - Presentation Details

Abstract Details

Title: Understanding the Outer Solar System through Characterized Surveys: The Missing Small Members of the Haumea Family

Presenter: Rosemary Pike


The Outer Solar Systems Origins Survey Ensemble includes OSSOS, the Alexandersen (2016) Survey, and CFEPS HiLat, four large surveys optimized for Trans-Neptunian objects (TNO) detection. Critically, the observational biases of the surveys were well documented, so the intrinsic populations of distant TNOs can be modeled. Three TNOs were discovered with orbital parameters consistent with the Haumea family, the only known collisional family in the Kuiper belt. These three objects have ejection velocities ΔV<160 m/s; the majority of TNOs discovered within this space are Haumea family members. 2013 UQ15 is conclusively a Haumea family member, with a ΔV=37 m/s and solar colors, and is the largest of the three family member candidates. Although OSSOS is sensitive to Haumea family members to a limiting Hr absolute magnitude of 9.5, the smallest of these three objects is Hr =7.9. If these objects share an absolute magnitude distribution with the other dynamically excited populations in the Kuiper belt, small Haumea family members Hr >8 should account for ~50% of the detections. This requires that the Haumea family be characterized by a single shallow H-distribution slope; our preferred slope is α=0.3. Using the three OSSOS Ensemble detections and survey characteristics with this H-distribution and a model of the Haumea family orbital distribution, we determine that the stable non-resonant Haumea family has 450 (-390 720) members with Hr<9.5 and ΔV<160 m/s. Assuming these objects have a density of water ice, albedos of 80%, and estimating the loss due to unstable or resonant family members, we estimate that the cumulative mass of the original Haumea family was about 3% of the present mass of Haumea.