Evidence for a seasonally dependent ring plasma in the region between Saturn's A Ring and Enceladus' orbit

A. M. Persoon; D. A. Gurnett; W. S. Kurth; J. B. Groene; J. B. Faden

doi:10.1002/2015JA021180

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Evidence for a seasonally dependent ring plasma in the region between Saturn's A Ring and Enceladus' orbit

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Evidence for a seasonally dependent ring plasma in the region between Saturn's A Ring and Enceladus' orbit

A. M. Persoon, D. A. Gurnett, W. S. Kurth, J. B. Groene and J. B. Faden

Journal of geophysical research. Space physics, Vol.120(8), pp.6276-6285

08/01/2015

DOI: 10.1002/2015JA021180

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Abstract

Equatorial electron density measurements from the Cassini Radio and Plasma Wave Science experiment are derived from the upper hybrid resonance frequency from Saturn Orbit Insertion (SOI) on 1 July 2004 through 21 May 2013. These densities are used to determine the characteristics of the plasma in the inner magnetosphere of Saturn between the outer edge of the A Ring and the orbit of Enceladus. Electron densities obtained when Cassini first arrived at Saturn on 1 July 2004 showed a plasma distribution decreasing radially outward from Saturn in the direction of Enceladus, the expected distribution of a centrifugally driven plasma expanding radially outward from a source in the main rings. We examine equatorial electron densities in the region between 2.4 and 4.0 R-s and show that the density measurements in this region exhibit a strong seasonal dependence resulting from photon-induced decomposition of icy particles on the ring surfaces, a decomposition process which is controlled by the solar incidence angle. This seasonal dependence will have plasma density implications for Cassini when the spacecraft returns to the region just beyond the A Ring in 2016.

Astronomy & Astrophysics

Physical Sciences

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Details

Title: Subtitle: Evidence for a seasonally dependent ring plasma in the region between Saturn's A Ring and Enceladus' orbit
Creators: A. M. Persoon - University of Iowa
D. A. Gurnett - University of Iowa
W. S. Kurth - University of Iowa
J. B. Groene - University of Iowa
J. B. Faden - University of Iowa
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.120(8), pp.6276-6285
DOI: 10.1002/2015JA021180
ISSN: 2169-9380
eISSN: 2169-9402
Publisher: Amer Geophysical Union
Number of pages: 10
Grant note: 1415150 / NASA; National Aeronautics & Space Administration (NASA) Jet Propulsion Laboratory; National Aeronautics & Space Administration (NASA)
Language: English
Date published: 08/01/2015
Academic Unit: Physics and Astronomy
Record Identifier: 9984455556102771

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