Presentation Abstract

Presentation Number 120.02
Presentation Time: Monday, Jun 11, 2012, 2:10 PM - 2:20 PM
Title Tidal Evolution of the Quaoar-Weywot System
Author Block Wesley Fraser1, M. E. Brown2, K. Batygin2, A. Bouchez3
1Herzberg Institute of Astrophysics, Canada, 2California Institute of Technology, 3Giant Magellan Telescope Observatory.
Abstract In some ways, the Kuiper Belt binary system, Quaoar-Weywot, is quite similar to the the Eris-Dysnomia system. The primaries of both systems are large, and both systems have high mass ratios of ~105:1. Unlike Eris however, Quaoar appears to have an unexpectedly high mass, and therefore has a high density, p>3 g cm-3. Furthermore, while Dysnomia is found on a nearly circular orbit, Weywot’s orbit appears to have a high eccentricity, e~0.1. We will present new Keck adaptive optics observations of the Quaoar-Weywot system which confirm both Quaoar’s high mass, of 1.3−1.4 × 1021 kg and Weywot’s eccentricity, e=0.13-0.16. We will present a reanalysis of the tidal orbital evolution of the Quoaor-Weywot system and contrast this with that of the Eris-Dysnomia system. From order-of-magnitude estimates, we find that with plausible values of the effective tidal dissipation factor for both bodies, tidal evolution is, at least in principle, compatible with the current orbits of Weywot and Dysnomia. That is, Dysnomia’s orbital eccentricity will decay on very short timescales, while Weywot’s eccentricity either remains constant, or evolves to higher values. Finally, we present tidal evolution simulations which demonstrate that, unless Quaoar were unusually non-dissipative, Weywot’s eccentricity could not have tidally evolved to its current value from an initially circular orbit. Rather, some other mechanism has raised its eccentricity post-formation, or Weywot formed with a non-negligible eccentricity.