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Size and Shape of Chariklo from Multi-epoch Stellar Occultations
- Source :
- Astronomical Journal, Astronomical Journal, American Astronomical Society, 2017, 154 (4), pp.159. ⟨10.3847/1538-3881/aa8956⟩, The Astronomical Journal, The Astronomical Journal, American Astronomical Society, 2017, 154 (4), pp.159. ⟨10.3847/1538-3881/aa8956⟩, The Astronomical Journal, 2017, 154 (4), pp.159. ⟨10.3847/1538-3881/aa8956⟩
- Publication Year :
- 2017
- Publisher :
- HAL CCSD, 2017.
-
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, tri-axial ellipsoid and Jacobi ellipsoid) and we use a Bayesian approach to estimate the corresponding parameters. The spherical model has a radius $R=129\pm3$ km. The Maclaurin model has equatorial and polar radii $a=b=143^{+3}_{-6}$ km and $c=96^{+14}_{-4}$ km, respectively, with density $970^{+300}_{-180}$ kg m$^{-3}$. The ellipsoidal model has semiaxes $a=148^{+6}_{-4}$ km, $b=132^{+6}_{-5}$ km and $c=102^{+10}_{-8}$ km. Finally, the Jacobi model has semiaxes $a$=157$\pm$4 km, $b$=139$\pm$ 4 km and $c$=86$\pm$1 km, and density $796^{+2}_{-4}$ kg m$^{-3}$ . 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 Chariklo's mass of 6-8$\times10^{18}$ kg places the rings close to the 3:1 resonance between the ring mean motion and Chariklo's rotation period.<br />Comment: Accepted for publication in AJ
- Subjects :
- Earth and Planetary Astrophysics (astro-ph.EP)
Physics
Rotation period
[PHYS]Physics [physics]
010504 meteorology & atmospheric sciences
FOS: Physical sciences
Astronomy and Astrophysics
Radius
Astrophysics
Light curve
01 natural sciences
Ellipsoid
Photometry (optics)
Spherical model
Mean motion
13. Climate action
Space and Planetary Science
Geometric albedo
0103 physical sciences
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
010303 astronomy & astrophysics
ComputingMilieux_MISCELLANEOUS
Astrophysics - Earth and Planetary Astrophysics
0105 earth and related environmental sciences
Subjects
Details
- Language :
- English
- ISSN :
- 00046256, 15383881, 0004637X, 20418205, 15383873, 15384357, 00046361, and 00027537
- Database :
- OpenAIRE
- Journal :
- Astronomical Journal, Astronomical Journal, American Astronomical Society, 2017, 154 (4), pp.159. ⟨10.3847/1538-3881/aa8956⟩, The Astronomical Journal, The Astronomical Journal, American Astronomical Society, 2017, 154 (4), pp.159. ⟨10.3847/1538-3881/aa8956⟩, The Astronomical Journal, 2017, 154 (4), pp.159. ⟨10.3847/1538-3881/aa8956⟩
- Accession number :
- edsair.doi.dedup.....0f09a719a6f508787c028a8878b99041