Let It Go: Geophysically Driven Ejection of the Haumea Family Members

Abstract

We present a new model for Haumea’s formation and evolution that relies on geophysical and geochemical data informed from observations of Haumea and meteorites to explain the characteristics of Haumea and its dynamical family. We hypothesize that after the impact of two partially differentiated Kuiper Belt objects, Haumea’s rocky core grew, decreasing its moment of inertia (MOI), spinning it up to the point that icy material was ejected from its surface. This ice, carrying about 3% of Haumea’s mass and 14% of its initial angular momentum, comprises the Haumean dynamical family and the ring system and moons observed today. Later, melted ice hydrated Haumea’s core and it grew, increasing Haumea’s MOI and spinning it down to the modern value. We use the geophysical code kyushu to demonstrate that solutions exist for a Haumea in hydrostatic equilibrium at each of these hypothesized stages. Geochemical modeling using the IcyDwarf code constrains the formation of Haumea’s core and the creation of the collision family to have occurred after roughly 150–160 Myr of solar system evolution (4.41 ± 0.01 Gyr ago). Hydration of the core was complete by about 0.20 Gyr, but a substantial subsurface ocean with half the mass of Earth’s oceans persisted until it froze at about 0.45 Gyr, making Haumea the solar system’s most distant potential relict ocean world.

Synchronous Rotation in the (136199) Eris–Dysnomia System

“…The giant-impact mechanism is favored for the satellites of large TNOs (e.g., Canup 2005;Brown et al 2006;Canup 2011), though capture (Goldreich et al 2002) and the collision of two objects within the Hill sphere of a third (Weidenschilling 2002) are also potential options. Another potential formation mechanism is rotational fission, perhaps induced by collision, which has been proposed in particular for the Haumea system (Ortiz et al 2012;Noviello et al 2022).…”

Beyond Point Masses. III. Detecting Haumea’s Nonspherical Gravitational Field

“…There is still much debate in the literature on the original reason that proto-Haumea had too much angular momentum: Proudfoot & Ragozzine (2022) propose the merger of a near-equal-mass binary similar to Pluto-Charon, perhaps triggered by Kozai cycles initiated due to Haumea's placement on a higher inclination orbit. Noviello et al (2022) point out that internal evolution could change Haumea's moment of inertia, spinning it up past the point of breakup. Ortiz et al (2012) and others suggest that it may be the cumulative effect of many smaller impacts, though starting with a rapid rotation would significant increase the probability that a random walk would lead to such a rapid rotation.…”

“…Haumea's shape, determined by both light-curve observations (Rabinowitz et al 2006) and stellar occultations (Ortiz et al 2017), is significantly nonspherical due to its 3.9 hr rotation period. Haumea and its satellites may have formed during a collision, which simultaneously spun up Haumea, created the satellites, and also formed Haumea's unique, icy collisional family (Leinhardt et al 2010;Proudfoot & Ragozzine 2022), but there remains some disagreement on these circumstances (e.g., Ortiz et al 2012;Campo Bagatin et al 2016;Noviello et al 2022). Connecting a formation model to all of the system's unique characteristics has been difficult despite many proposals (e.g., Proudfoot & Ragozzine 2019).…”

The Impact of Serpentinization on the Initial Conditions of Satellite Forming Collisions of Large Kuiper Belt Objects

“…The serpentinization process has been invoked to explain the interior of Pluto (see e.g., Vance et al 2007), and it has been proposed by Dunham et al (2019) that Haumea's core underwent serpentinization in the past. Noviello et al (2022) presented a detailed internal evolution model of Haumea including the serpentinization process that led to core growth and increased Haumea's moment of inertia on a few hundred million-year timescale, assuming that the core forming event occurred ∼50 Myr after Ca-Al-rich inclusion (CAI) formation.…”

“…These systems are very different from the smaller binaries where the components are often found as nearly equal-sized with a large relative separation, suggesting different formation conditions for the two types of objects. While different formation scenarios are possible (e.g., mass ejection due to fast rotation, see Noviello et al 2022), the satellites of the outer solar system dwarf planets were most likely created by energetic collisions between massive planetesimals (Holler et al 2021a).…”