Presentation #206.05 in the session “Centaurs and Kuiper Belt Objects: Formation and Evolution”.
Haumea is a dwarf planet with an extremely rapid spin (3.9 hr period) and a strong water ice spectral signature. A group of almost 20 Kuiper Belt objects (KBOs) share Haumea’s strong water ice spectral feature and reside on dynamically similar orbits. This group is thought to be a collisional family, the only known family in the Kuiper belt. Ever since the discovery of the Haumea family, no fully self consistent models for the formation have been suggested. The most promising model, a graze-and-merge collision between two differentiated, equal sized bodies at almost zero relative velocity, can match almost all observed characteristics of the family, with the exception of the ejection direction distribution (Proudfoot & Ragozzine 2019). It also suffers from a vanishingly low probability, due to the progenitors’ large size and low relative velocity. Here, we will present a modification of this model which matches all of the features of the family, while remaining relatively probable. We propose that a large equal size binary undergoes a graze-and-merge collision, creating a small, compact family with strong water ice spectra. This family is then immediately mixed by the tail end of Neptune’s migration, erasing the unique ejection direction distribution. This model, while explaining the formation of the Haumea family, naturally matches the context of the formation of the outer solar system.