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Science 7 October 1983:
Vol. 222. no. 4619, pp. 57 - 60
DOI: 10.1126/science.222.4619.57
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Articles

Eccentric Ringlet in the Maxwell Gap at 1.45 Saturn Radii: Multi-Instrument Voyager Observations

L. W. ESPOSITO 1, N. BORDERIES 2, P. GOLDREICH 2, J. N. CUZZI 3, J. B. HOLBERG 4, A. L. LANE 5, R. B. POMPHREY 5, R. J. TERRILE 5, J. J. LISSAUER 6, E. A. MAROUF 7, and G. L. TYLER 7

1 Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder 80309
2 Division of Geophysics and Planetary Science, California Institute of Technology, Pasadena 91125
3 NASA Ames Research Center, Moffett Field, California 94035
4 Earth and Space Science Institute, University of Southern California, Tucson, Arizona 85767
5 Jet Propulsion Laboratory, Pasadena, California 91109
6 Astronomy Department and Mathematics Department, University of California, Berkeley 94720
7 Center for Radar Astronomy, Stanford University, Stanford, California 94305

The Voyager spacecraft observed a narrow, eccentric ringlet in the Maxwell gap (1.45 Saturn radii) in Saturn's rings. Intercomparison of the Voyager imaging, photopolarimeter, ultraviolet spectrometer, and radio science observations yields results not available from individual observations. The width of the ringlet varies from about 30 to about 100 kilometers, its edges are sharp on a radial scale < 1 kilometer, and its opacity exhibits a double peak near the center. The shape and width of the ringlet are consistent with a set of uniformly precessing, confocal ellipses with foci at Saturn's center of mass. The ringlet precesses as a unit at a rate consistent with the known dynamical oblateness of Saturn; the lack of differential precession across the ringlet yields a ringlet mass of about 5 x 1018 grams. The ratio of surface mass density to particle cross-sectional area is about five times smaller than values obtained elsewhere in the Saturn ring system, indicating a relatively larger fraction of small particles. Also, comparison of the measured transmission of the ringlet at radio, visible, and ultraviolet wavelengths indicates that about half of the total extinction is due to particles smaller than 1 centimeter in radius, in contrast even with nearby regions of the C ring. However, the color and brightness of the ringlet material are not measurably different from those of nearby C ring particles. We find this ringlet is similar to several of the rings of Uranus.

Submitted on April 5, 1983
Revised on July 6, 1983


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Titan -1:0 Nodal Bending Wave in Saturn's Ring C.
P. A. Rosen and J. J. Lissauer (1988)
Science 241, 690-694
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Voyager 2 in the Uranian System: Imaging Science Results.
B. A. Smith, B. A. SMITH, L. A. SODERBLOM, R. BEEBE, D. BLISS, J. M. BOYCE, A. BRAHIC, G. A. BRIGGS, R. H. BROWN, S. A. COLLINS, et al. (1986)
Science 233, 43-64
   Abstract »    PDF »


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