A Statistical Review of Light Curves and the Prevalence of Contact Binaries in the Kuiper Belt

Abstract

We investigate what can be learned about a population of distant KBOs by studying the statistical properties of their light curves. Whereas others have successfully inferred the properties of individual, highly variable KBOs, we show that the fraction of KBOs with low amplitudes also provides fundamental information about a population. Each light curve is primarily the result of two factors: shape and orientation. We consider contact binaries and ellipsoidal shapes, with and without flattening. After developing the mathematical framework, we apply it to the existing body of KBO light curve data. Principal conclusions are as follows. (1) When using absolute magnitude H as a proxy for size, it is more accurate to use the maximum of the light curve rather than the mean. (2) Previous investigators have noted that smaller KBOs have higher-amplitude light curves, and have interpreted this as evidence that they are systematically more irregular in shape than larger KBOs; we show that a population of flattened bodies with uniform proportions could also explain this result. (3) Our analysis indicates that prior assessments of the fraction of contact binaries in the Kuiper Belt may be artificially low. (4) The pole orientations of some KBOs can be inferred from observed changes in their light curves; however, these KBOs constitute a biased sample, whose pole orientations are not representative of the population overall. (5) Although surface topography, albedo patterns, limb darkening, and other surface properties can affect individual light curves, they do not have a strong influence on the statistics overall. (6) Photometry from the OSSOS survey is incompatible with previous results and its statistical properties defy easy interpretation. We also discuss the promise of this approach for the analysis of future, much larger data sets such as the one anticipated from the Rubin Observatory.

References in corpus (17)

• The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation
• Initial results from the New Horizons exploration of 2014 MU69, a small Kuiper Belt Object
• The solar nebula origin of (486958) Arrokoth, a primordial contact binary in the Kuiper belt
• The Geology and Geophysics of Kuiper Belt Object (486958) Arrokoth
• Binary Survival in the Outer Solar System
• Size and shape of Chariklo from multi-epoch stellar occultations
• Light Curves of Dwarf Plutonian Planets and other Large Kuiper Belt Objects: Their Rotations, Phase Functions and Absolute Magnitudes
• Rotational properties of the binary and non-binary populations in the Trans-Neptunian belt
• Trans-Neptunian binaries (2018)
• Dumb-bell-shaped equilibrium figures for fiducial contact-binary asteroids and EKBOs
• Pushing the limits: K2 observations of the trans-Neptunian objects 2002 GV31 and (278361) 2007 JJ43
• 2004 TT357: A potential contact binary in the Trans-Neptunian belt
• Uncertain classification of Variable Stars: handling observational GAPS and noise
• Surface composition and dynamical evolution of two retrograde objects in the outer solar system: 2008 YB3 and 2005 VD
• A possible dynamically Cold Classical contact binary: (126719) 2002 CC249
• Light curves of ten Centaurs from K2 measurements
• The Rotational Light Curve of (79360) Sila-Nunam, an Eclipsing Binary in the Kuiper Belt

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