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What Perturbs the ggrdgr Rings of Uranus?
Science (New York, N.Y.)
|January 31, 1986
Summary
Large perturbations in Uranus
Area of Science:
- Planetary Science
- Astronomy
- Orbital Dynamics
Background:
- Uranus possesses nine known rings, with the gamma and delta rings exhibiting significant radial perturbations.
- These two rings deviate from predictable Keplerian orbits, showing root-mean-square residuals of approximately 3 kilometers, unlike the other seven rings.
Purpose of the Study:
- To investigate the causes of large radial perturbations in Uranus's gamma and delta rings.
- To analyze perturbation patterns for evidence of Lindblad resonances and identify potential shepherd satellites.
Main Methods:
- Examined perturbation patterns of the gamma and delta rings for Lindblad resonances (m=0, 1, 2, 3, 4).
- Analyzed radial residuals of the beta ring for resonance matching.
- Assessed the likelihood of resonance being caused by viscous instability versus external factors.
Main Results:
- The beta ring's radial residuals align well with a 2:1 Lindblad resonance, suggesting an undiscovered satellite.
- This potential satellite orbits Uranus at 76,522 +/- 8 km with a period of 15.3595 +/- 0.0001 hours and a radius of 75-100 km.
- No low-order Lindblad resonance matches the gamma ring perturbations, indicating they are likely caused by large shepherd satellites.
Conclusions:
- A 2:1 Lindblad resonance strongly suggests an undiscovered satellite near the beta ring, detectable by Voyager.
- The gamma ring perturbations are likely caused by one or more large shepherd satellites, visible in Voyager images.
- The resonance for the beta ring is unlikely to stem from viscous instability due to its location relative to the delta ring.
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