FastFind »   Lastname: doi:10.1029/ Year: Advanced Search  

AGU: Journal of Geophysical Research, Space Physics

 
Abstract
Cited By (0)
 

Abstract

Photometry and Polarimetry of Saturn’s Rings from Pioneer Saturn

Larry W. Esposito

Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80309

James P. Dilley

Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721

John W. Fountain

Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721

We present a profile of the average normal optical depth for Saturn’s rings between 1.22 and 2.35 Rs . In the A and B rings, horizontal inhomogeneities make these values deceptive. A thinner component of the B ring with optical depth less than 0.08 covers ½% to 4% of its surface area. In the A ring the more transparent component has optical depth τ s > 0.10 and covers more than 7% of its area. These thinner parts of the rings would rarely be apparent from earth-based observations. The particles in the C ring are larger than 15µ and different from those in the B and A rings. The C ring is either homogeneous with high albedo (in the red) ω ¯ 0 0.75 and forward scattering phase functions or shows a gradient in albedo with distance from Saturn. In the latter case the red albedo ranges from ω ¯ 0 0.3 at the inner edge of ring C to ω ¯ 0 0.65 at the outer edge, and the phase function is both moderately forward and backward scattering. Polarimetry of Saturn’s rings provides only an upper limit for the B ring polarization, p < 15%, which is consistent with predictions from ground-based data. In the outer A ring, the polarization is negative p(blue) = −7 ± 2%; p(red) = −1 ± 2%. Azimuthal variations are seen on the darkside of the A ring with a peak-to-trough ratio of 1.25. The position angle of the maximum is close to that seen from earth. No variations are seen in the B and C rings with an upper limit of 6%. The measured color of the A ring supports the many particle thick model of Saturn’s rings.

Received 7 May 1980; accepted 16 July 1980; .

Citation: Esposito, L. W., J. P. Dilley, and J. W. Fountain (1980), Photometry and Polarimetry of Saturn’s Rings from Pioneer Saturn, J. Geophys. Res., 85(A11), 5948–5956.

Cited By

Please wait one moment ...