Monday, Jun 11, 2012, 2:10 PM - 2:20 PM
Tidal Evolution of the Quaoar-Weywot System
, M. E. Brown
, K. Batygin
, A. Bouchez
Herzberg Institute of Astrophysics, Canada,
California Institute of Technology,
Giant Magellan Telescope Observatory.
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 ~10
:1. Unlike Eris however, Quaoar appears to have an unexpectedly high mass, and therefore has a high density, p>3 g cm
. 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 × 10
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.
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