The mass, orbit, and tidal evolution of the Quaoar–Weywot system
Here we present new adaptive optics observations of the Quaoar–Weywot system. With these new observations we determine an improved system orbit. Due to a 0.39 day alias that exists in available observations, four possible orbital solutions are available with periods of ∼11.6, ∼12.0, ∼12.4, and ∼12.8 days. From the possible orbital solutions, system masses of 1.3–1.5 ± 0.1 × 10^(21) kg are found. These observations provide an updated density for Quaoar of 2.7–5.0 g cm^(−3). In all cases, Weywot's orbit is eccentric, with possible values ∼0.13–0.16. We present a reanalysis of the tidal orbital evolution of the Quaoar–Weywot system. We have found that Weywot has probably evolved to a state of synchronous rotation, and has likely preserved its initial inclination over the age of the Solar System. We find that for plausible values of the effective tidal dissipation factor tides produce a very slow evolution of Weywot's eccentricity and semi-major axis. Accordingly, it appears that Weywot's eccentricity likely did not tidally evolve to its current value from an initially circular orbit. Rather, it seems that some other mechanism has raised its eccentricity post-formation, or Weywot formed with a non-negligible eccentricity.
Additional Information© 2012 Published by Elsevier Inc. Received 18 August 2011; Revised 5 November 2012; Accepted 8 November 2012; Available online 29 November 2012. W.F. would like to thank Alex Parker for his advice and help in determining correct orbital solutions. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The research upon which this paper is based was supported by National Aeronautic and Space Administration (NASA) Grant No. NNX09AB49G.
Accepted Version - 1211.1016.pdf