Weak dynamical effects in the Uranian ring system

1983 ◽  
Vol 88 ◽  
pp. 1053 ◽  
Author(s):  
A. P. Freedman ◽  
S. Tremaine ◽  
J. L. Elliot
Keyword(s):  
Ring System ◽  
Uranian Ring

Dynamics of eccentric and inclined ringlets

1984 ◽  
Vol 75 ◽  
pp. 341-343
Author(s):  
N. Borderies ◽  
P. Goldreich ◽  
S. Tremaine
Keyword(s):  
Semimajor Axis ◽  
Ring System ◽  
The Self ◽  
Uranian Ring ◽  
Self Gravity

The Saturn and Uranian ring system contain a number of narrow eccentric ringlets. Several of the Uranian ringlets are also inclined to the planet's equator. We show that the self-gravity is probably responsible for maintaining apse and node alignment across these ringlets. This hypothesis leads to the prediction that within each ringlet both the eccentricity and the inclination increase with semimajor axis.

Weak dynamical effects in the Uranian ring system

1984 ◽  
Vol 75 ◽  
pp. 457-458
Author(s):  
Adam P. Freedman ◽  
Scott Tremaine ◽  
James L. Elliot
Keyword(s):  
Close Association ◽  
Ring System ◽  
Convincing Evidence ◽  
Gravitational Forces ◽  
Ring Model ◽  
Maximum Change ◽  
Uranian Ring ◽  
The Masses ◽  
Three Body ◽  
Residual Errors

ABSTRACTA number of weak gravitational forces were examined for their kinematic effects on the Uranian ring system, in an attempt to account for residual errors of ~2 km in the ring positions and a few times 10-3deg/day in the apse precession rates. The principal conclusions are as follows: (1) perturbations by the five known satellites are too small to have observable effects with the best current estimates of the satellite masses. (2) Limits can be set on the masses of inter-ring “shepherd” satellites from their influence on precession rates and their radial perturbations on the rings. For example, the maximum mass of a shepherd satellite between rings 4 and 5 is ~ 1019gm. (3) Using the best available ring parameters, there is no convincing evidence that the rings are associated with resonances with known satellites. The only close association is of rings 5, α and γ with three-body resonances due to Miranda and Ariel. It is more likely that the putative shepherd satellites may occupy resonances. (4) The known satellites can cause anomalous residuals by changing the position of Uranus relative to the system barycenter during the occultation. The maximum change, so far, during the 1977 March 10 event, was 1.6 km. This effect will be investigated with the MIT Uranus ring model.

scholarly journals 20. Positions and Motions of Minor Planets, Comets and Satellites

1982 ◽  
Vol 18 (1) ◽  
pp. 195-210
Author(s):  
E Roemer
Keyword(s):  
Working Group ◽  
Ring System ◽  
Minor Planets ◽  
The Sun ◽  
Ring Plane ◽  
Ring Systems ◽  
The Earth ◽  
Uranian Ring

An avalanche of discoveries pertaining to the satellite and ring systems of Jupiter and Saturn followed from the encounters of Pioneer 11 with Saturn, of Voyagers 1 and 2 with both Jupiter and Saturn, and from the passage of the Earth through the Saturn ring plane, all of which occurred during the triennium. The first comet discovery from a spacecraft also occurred during the same interval, a coronagraph experiment on the satellite P78-1 apparently catching a Kreutz sungrazer in the last hours before it impacted the Sun on 1979 August 30. Several successfully observed occultations of stars by the Uranian ring system, by minor planets, and possibly by satellites of Neptune and Pluto testify to efforts inspired by the Commission’s Working Group on Prediction of Occultations.

The rings of Uranus

1984 ◽  
Vol 75 ◽  
pp. 155-164 ◽  
Author(s):  
James L. Elliot
Keyword(s):  
Equatorial Plane ◽  
Kinematic Model ◽  
Theoretical Explanation ◽  
Ring System ◽  
Structural Details ◽  
Sharp Edges ◽  
Orbital Precession ◽  
Uranian Ring ◽  
Occultation Data ◽  
Geometric Albedo

ABSTRACTThe Uranian ring system consists of nine, narrow rings that have an average geometric albedo of 0.02. Since their discovery in 1977, the rings have been regularly observed with the technique of stellar occultations, which provides a spatial resolution of about 0.1 km in the positions of ring segments and about 4 km resolution in their structural details. The occultation data are well fitted by a kinematic model that describes the rings as ellipses, which are inclined to the equatorial plane of Uranus and precess due to harmonic terms in the Uranian potential field. The main characteristics of the Uranian ring system that need a confirmed theoretical explanation are: narrow rings, sharp edges, uniform orbital precession, origin of the eccentricities and inclinations, the structure of the e ring, the structure of the η ring and the origin of the ring system.

Tidal breakup and origin of the Uranian ring system

1984 ◽  
Vol 75 ◽  
pp. 687-689
Author(s):  
P. Farinella ◽  
A. Milani ◽  
A.M. Nobili ◽  
P. Paolicchi
Keyword(s):  
Observational Data ◽  
Ring System ◽  
Dissipative Processes ◽  
Gravitational Torque ◽  
Gravitational Forces ◽  
Uranian Ring ◽  
Interparticle Collisions ◽  
Ring Material

The peculiar features of the Uranian ring system have posed several difficult dynamical problems. The mutual gravitational forces among the ring particles can ensure stability against the spreading due to differential precession of the orbits, but are not able to provide an effective confinement mechanism against dissipative processes like interparticle collisions (Farinella et al., 1978, 1980a). The existence of small undiscovered satellites inside the orbit of Miranda is not ruled out by the presently available observational data, and has been proposed by Goldreich and Tremaine (1979) as a possible solution for the confinement problem: each ring is supposed to lie between two different satellites exerting a gravitational torque which tends to repel ring material and prevents the collisional spreading.

scholarly journals Thermal Emission from the Uranian Ring System

2019 ◽  
Vol 158 (1) ◽  
pp. 47 ◽  
Author(s):  
Edward M. Molter ◽  
Imke de Pater ◽  
Michael T. Roman ◽  
Leigh N. Fletcher
Keyword(s):  
Thermal Emission ◽  
Ring System ◽  
Uranian Ring

Near-infrared spectra of the uranian ring system

Icarus ◽  
2013 ◽  
Vol 226 (1) ◽  
pp. 1038-1044 ◽  
Author(s):  
Katherine de Kleer ◽  
Imke de Pater ◽  
Máté Ádámkovics ◽  
Heidi Hammel
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Ring System ◽  
Near Infrared Spectra ◽  
Uranian Ring

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Effectiveness of Brushing Associated with Oral Irrigation in Maintenance of Peri-Implant Tissues and Overdentures: Clinical Parameters and Patient Satisfaction.

2020 ◽  
Author(s):  
Marcela Moreira Salles ◽  
Viviane de Cássia Oliveira ◽  
Ana Paula Macedo ◽  
Claudia Helena Silva-Lovato ◽  
Helena de Freitas Oliveira Paranhos
Keyword(s):  
Patient Satisfaction ◽  
Analogue Scale ◽  
Ring System ◽  
Complete Dentures ◽  
Gingival Index ◽  
Prosthetic Rehabilitation ◽  
Mean Values ◽  
Probing Depth ◽  
Significant Difference ◽  
High Level

Implant-supported prostheses hygiene and peri-implant tissues health are considered to be predictive factors for successful prosthetic rehabilitation. Therefore, the purpose of this study was to evaluate the effectiveness of brushing associated with oral irrigation measured as biofilm-removing capacity, maintenance of healthy oral tissues, and patient satisfaction. A randomized, crossover clinical trial was conducted with 38 patients who wore conventional maxillary complete dentures and mandibular overdentures retained by the O-ring system. The patients were instructed to use the following hygiene methods for 14 days: mechanical brushing [MB (brush and dentifrice - Control)]; and MB with oral irrigation [WP (Waterpik - Experimental)]. Biofilm-removing capacity and maintenance of healthy oral tissues were evaluated by the Modified Plaque Index (PI), Gingival Index (GI), Probing Depth (PD), and Bleeding on Probing Index (BP) recorded at baseline and after each method. In parallel, patients answered a specific questionnaire using a Visual Analogue Scale after each hygiene method. Data were analyzed by Friedman and Wilcoxon tests (α=0.05). The results showed significantly lower PI, GI, PD, and BP indices after application of the hygiene methods (P<0.001) than those observed at baseline. However, no significant difference was found between MB and WP. The satisfaction questionnaire responses to both methods showed high mean values for all questions, with no statistically significant difference found between the answers given after the use of MB and WP (P>0.05). The findings suggest that WP was effective in reducing PI, GI, PD, and BP indices and provided a high level of patient satisfaction.

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