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The Mimas Ghost Revisited: An Analysis of the Electron Flux and Electron Microsignatures Observed in the Vicinity of Mimas at Saturn

Chenette, D. L. and Stone, E. C. (1983) The Mimas Ghost Revisited: An Analysis of the Electron Flux and Electron Microsignatures Observed in the Vicinity of Mimas at Saturn. Journal of Geophysical Research A, 88 (A11). pp. 8755-8764. ISSN 0148-0227. doi:10.1029/JA088iA11p08755.

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An analysis of the electron absorption signature observed by the Cosmic Ray System on Voyager 2 near the orbit of Mimas is presented. We find that these observations cannot be explained as the absorption signature of Mimas. Combining Pioneer 11 and Voyager 2 measurements of the electron flux at Mimas's orbit (L = 3.1), we find an electron spectrum where most of the flux above ∼100 keV is concentrated near 1 to 3 MeV. This spectral form is qualitatively consistent with the band-pass filter model of Van Allen et al. (1980b). The expected Mimas absorption signature is calculated from this spectrum neglecting radial diffusion. Since no Mimas absorption signature was observed in the inbound Voyager 2 data, a lower limit on the diffusion coefficient for MeV electrons at L = 3.1 of D > 10^(−8) R_s^² s^(−1) is obtained. With a diffusion coefficient this large, both the Voyager 2 and the Pioneer 11 small-scale electron absorption signature observations in Mimas's orbit are enigmatic. Thus we refer to the mechanism for producing these signatures as the Mimas ghost. A cloud of material in orbit with Mimas may account for the observed electron signature if the cloud is at least 1% opaque to electrons across a region extending over a few hundred kilometers.

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Stone, E. C.0000-0002-2010-5462
Additional Information:© 1983 by the American Geophysical Union. Manuscript Accepted: 22 Apr 1983. Manuscript Received: 2 Feb 1983. We greatly appreciate the efforts of R. E. Vogt and other members of the team from Caltech, Goddard Space Flight Center, the University of Arizona, and the University of New Hampshire who were responsible for the success of the CRS investigation. Useful discussions with A. W. Schardt and M. Schulz are gratefully acknowledged. We thank the Voyager Navigation Team of the Jet Propulsion Laboratory for providing accurate positions of the satellites of Saturn. This work was supported by NASA under NAS7-918 and NGR 05-002-160. DLC acknowledges additional support by the Aerospace Corporation's sponsored research program. The editor thanks K. R. Pyle and S. Krimigis for their assistance in evaluating this paper.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASANGR 05-002-160
Aerospace CorporationUNSPECIFIED
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Space Radiation Laboratory1983-02
Issue or Number:A11
Record Number:CaltechAUTHORS:20140211-084948927
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Official Citation:Chenette, D. L., and E. C. Stone (1983), The Mimas Ghost revisited: An analysis of the electron flux and electron microsignatures observed in the vicinity of Mimas at Saturn, J. Geophys. Res., 88(A11), 8755–8764, doi:10.1029/JA088iA11p08755.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43764
Deposited By: Ruth Sustaita
Deposited On:11 Feb 2014 17:05
Last Modified:10 Nov 2021 16:42

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