36th DPS Meeting, 8-12 November 2004
Session 19 Rings
Poster I, Tuesday, November 9, 2004, 4:00-7:00pm, Exhibition Hall 1A

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[19.17] A and B Ring Wakes in High Dynamic Range Radio Maps of Saturn

L. A. Molnar, E. M. Crull (Calvin College), D. E. Dunn (Sierra College)

We have made new total intensity and polarized images at 3.6 cm wavelength of Saturn near maximum ring tilt (26.3 degrees). These Very Large Array maps have higher dynamic range than previous ones, and reveal a variety of new features.

The total intensity of the A ring can be traced accurately over the full range of azimuth and shows clearly the features predicted by Dunn et al. (2004, Icarus, 171, 183) in wake simulations: strong east-west asymmetry on the far side of the rings, but not on the near.

To our surprise, the inner portion of the B ring shows the same asymmetry signature, although with reduced amplitude. Furthermore, the same portion of the B ring shows asymmetry as it passes in front of the planet, a signature of wakes we have previously found in the A ring. (This was not seen in previous images, for which the B ring was too foreshortened to allow any direct transmission.) Taken together, this is the first evidence of wakes in this portion of the rings. This is not inconsistent with dynamical simulations, however, which show less organized but recognizable wakes at this radius.

We will discuss quantitative implications for wake parameters in both rings based on modeling of the data with our simrings radiative transfer code.

The polarized intensity map allows us to trace the strength and orientation of the polarized light over the full range of ring azimuths as well. The result is qualitatively consistent with polarization produced perpendicular to the source-ring-observer plane, with greatest strength at 90 degree scattering angle. In particular, the pattern of observed polarization position angle is consistent with light dominated by single scattering of light from the southern hemisphere (diffusely reflected light).

This work was supported in part by a grant from Research Corporation.

The author(s) of this abstract have provided an email address for comments about the abstract: lmolnar@calvin.edu

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.