A Faster Spin for Quaoar?

Recent stellar occultations indicate that Quaoar's apparent shape is consistent across all observed events, suggesting that the body is close to a Maclaurin spheroid rather than a triaxial ellipsoid. Such a nearly axisymmetric figure naturally implies a single-peaked rotational light curve with a period of ∼8.8 h, instead of the previously proposed double-peaked 17.7 h period. In this work, we investigate which patterns of surface albedo variation can reproduce the observed visible and infrared thermal emission light curves under this faster rotation scenario. 

We further show that while standard tidal evolution can explain Weywot's present orbit, it cannot explain Quaoar's 17.7 h rotation period. If the true rotation period is instead close to half this value, the tension largely disappears, and Quaoar's figure, primordial rotation, and the long-term tidal influence of Weywot become mutually consistent. Moreover, the dynamical evolution of Quaoar's inner ring provides independent constraints that could be tested using sufficiently high-resolution occultation measurements.