|
|||||
|
|
Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission |
|
| Authors: | David E Dunn Lawrence A Molnar Imke de Pater |
| Institution: | a Astronomy Department, Sierra College, Rocklin, CA 95677, USA b Astronomy Department, University of California, Berkeley, CA 94720, USA c Department of Physics and Astronomy, Calvin College, Grand Rapids, MI 49546, USA d Space Science Division, MS 245-3, NASA Ames Research Center, Moffett Field, CA 94035, USA |
| Abstract: | We present a new Very Large Array (VLA) image of Saturn, made from data taken in October 1998 at a wavelength of λ3.6 cm. The moderate ring opening angle (B≈15°) allows us to explore direct transmission of microwave photons through the A and C rings. We find a strong asymmetry of photons transmitted through the A ring, but not in the C ring, a new diagnostic of wake structure in the ring particles. We also find a weak asymmetry between east and west for the far side of the ansae. To facilitate quantitative comparison between dynamic models of the A ring and radio observations, we extend our Monte Carlo radiative transfer code (described in Dunn et al., 2002, Icarus 160, 132-160) to include idealized wakes. We show the idealized model can reproduce the properties of dynamic simulations in directly transmitted light. We examine the model behavior in directly transmitted and scattered light over a range of physical and geometric wake parameters. Finally, we present a wake model with a plausible set of physical parameters that quantitatively reproduces the observed intensity and asymmetry of the A ring both across the planet and in the ansae. |
| Keywords: | Saturn planetary rings Saturn atmosphere Saturn atmospheres dynamics Radiative transfer Radio observations |
| 本文献已被 ScienceDirect 等数据库收录！ | |