Size and Shape of Chariklo from Multi-epoch Stellar Occultations
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Leiva_2017_AJ_154_159.pdf
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3.37 MB
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Author(s)
Gulbis, Amanda A. S.
Date Issued
September 2017
Journal
Astronomical Journal
Publisher
IOP Publishing
Citation
Leiva, R. et al. “Size and Shape of Chariklo from Multi-Epoch Stellar Occultations.” The Astronomical Journal 154, 4 (September 2017): 159 © 2017 The American Astronomical Society
Version
Final published version
Abstract
We use data from five stellar occultations observed between 2013 and 2016 to constrain Chariklo's size and shape, and the ring reflectivity. We consider four possible models for Chariklo (sphere, Maclaurin spheroid, triaxial ellipsoid, and Jacobi ellipsoid), and we use a Bayesian approach to estimate the corresponding parameters. The spherical model has a radius R = 129 ±3 km. The Maclaurin model has equatorial and polar radii a = b 143 [subscript -6][superscript +3] km and c = 96 [subscript -4][superscript +14] km, respectively, with density 970 [subscript -180][superscript +300] kg m [superscript -3]. The ellipsoidal model has semiaxes a = 148 [subscript -4][superscript +6] km, b = 132[subscript -5][superscript +6] km, and a = c 102 [subscript -8][superscript +10] km. Finally, the Jacobi model has semiaxes a = 157 ±4 km, b = 139 ±4 km, and c = 86 ±1 km, and density 796 [subscript -4] [superscript +2] kg m[superscript -3]. Depending on the model, we obtain topographic features of 6-11 km, typical of Saturn icy satellites with similar size and density. We constrain Chariklo's geometric albedo between 3.1% (sphere) and 4.9% (ellipsoid), while the ring I/F reflectivity is less constrained between 0.6% (Jacobi) and 8.9% (sphere). The ellipsoid model explains both the optical light curve and the long-term photometry variation of the system, giving a plausible value for the geometric albedo of the ring particles of 10%-15%. The derived mass of Chariklo of 6-8 ×10 18 kg places the rings close to 3:1 resonance between the ring mean motion and Chariklo's rotation period.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.3847/1538-3881/aa8956
