Sublimation as an effective mechanism for flattened lobes of (486958) Arrokoth

Abstract

The New Horizons spacecraft's flyby of Kuiper Belt Object (KBO) (486958) Arrokoth revealed a bilobed shape with highly flattened lobes both aligned to its equatorial plane, and a rotational axis almost aligned to the orbital plane (obliquity ~99 deg). Arrokoth belongs to the Cold Classical Kuiper Belt Object population that occupies dynamically undisturbed orbits around the Sun, and as such, is a primitive object that formed in situ. Therefore, whether its shape is primordial or evolutionary carries important implications for understanding the evolution of both KBOs and potentially their dynamically derived objects, Centaurs and Jupiter Family Comets (JFC). Applying our mass loss driven shape evolution model (MONET), here we suggest that the current shape of Arrokoth could be of evolutionary origin due to volatile outgassing in a timescale of about 1 to 100 Myr, while its spin state would not significantly affected. We further argue that such a process may be ubiquitous in the evolution of the shape of KBOs shortly after their formation. This shape changing process could also be reactivated when KBOs dynamically evolve to become Centaurs and then JFCs and receive dramatically increased solar heating.

20 pages, 10 figures, a revised version is published in Nature Astronomy (2020)

References in corpus (10)

• Initial results from the New Horizons exploration of 2014 MU69, a small Kuiper Belt Object
• The solar nebula origin of (486958) Arrokoth, a primordial contact binary in the Kuiper belt
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• CO in distantly active comets
• Color, Composition, and Thermal Environment of Kuiper Belt Object (486958) Arrokoth
• Constraints on cometary surface evolution derived from a statistical analysis of 67P's topography
• Hall Effect in Protostellar Disc Formation and Evolution
• Crater Density Predictions for New Horizons flyby target 2014 MU69
• Constraining the final merger of contact binary(486958) Arrokoth with soft-sphere discrete element simulations
• The Phenomenon of Shape Evolution due to Solar Driven Outgassing for Analogues of Small Kuiper Belt Objects

Cited by in corpus (3)

• Modification of icy planetesimals by early thermal evolution and collisions: Constraints for formation time and initial size of comets and small KBOs
• Considering contact forces during the formation of planetesimals by gravitational collapse: mutual orbits, spin states, and shapes
• Direct contact binary planetesimal formation from gravitational collapse