Rotational fission of Trans-Neptunian Objects. The case of Haumea

TL;DR

This paper investigates rotational fission as a formation mechanism for Trans-Neptunian Objects, especially Haumea, using observational evidence and N-body simulations, suggesting it could explain binary systems and related bodies in the belt.

Contribution

It provides evidence that rotational fission has occurred in TNOs, presents a case study of Haumea, and demonstrates through simulations that fission can produce satellites and related bodies.

Findings

Haumea's rapid spin likely evolved from a primordial state.

Rotational fission can produce satellite systems and asteroid-like families.

Simulations support the feasibility of fission creating associated bodies.

Abstract

We present several lines of evidence based on different kinds of observations to conclude that rotational fission has likely occurred for a fraction of the known Trans-Neptunian Objects (TNOs). It is also likely that a number of binary systems have formed from that process in the trans-neptunian belt. We show that Haumea is a potential example of an object that has suffered a rotational fission. Its current fast spin would be a slight evolution of a primordial fast spin, rather than the result of a catastrophic collision, because the percentage of objects rotating faster than 4 hours would not be small in a maxwellian distribution of spin rates that fits the current TNO rotation database. On the other hand, the specific total angular momentum of Haumea and its satellites falls close to that of the high size ratio asteroid binaries, which are thought to be the result of rotational fissions or mass shedding. We also present N-body simulations of rotational fissions applied to the case of Haumea, which show that this process is feasible, might have generated satellites, and might have even created a "family" of bodies orbitally associated to Haumea. The orbitally associated bodies may come from the direct ejection of fragments according to our simulations, or through the evolution of a proto-satellite formed during the fission event. Also, the disruption of an escaped fragment after the fission might create the orbitally related bodies. If any of those mechanisms are correct, other rotational fission families may be detectable in the trans-neptunian belt in the future, and perhaps even TNO pairs might be found (pairs of bodies sharing very similar orbital elements, but not bound together).