The lens feature on the inner saturnian satellites

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• 作者：C. Paranicas^a ; ^{chris.paranicas@jhuapl.edu" class="auth_mail} ; E. Roussos^b ; ^{Roussos@mps.mpg.de" class="auth_mail} ; R.B. Decker^a ; ^{Rob.decker@jhuapl.edu" class="auth_mail} ; R.E. Johnson^c ; ^{rej@virginia.edu" class="auth_mail} ; A.R. Hendrix^e ; ^{ahendrix@psi.edu" class="auth_mail} ; P. Schenk^d ; ^{schenk@lpi.usra.edu" class="auth_mail} ; T.A. Cassidy^f ; ^{Timothy.Cassidy@lasp.colorado.edu" class="auth_mail} ; J.B. Dalton III^g ; ^{James.B.Dalton@jpl.nasa.gov" class="auth_mail} ; C.J.A. Howett^h ; ^{howett@boulder.swri.edu" class="auth_mail} ; P. Kollmann^a ; ^{peter.kollmann@jhuapl.edu" class="auth_mail} ; W. Patterson^a ; ^{wes.patterson@jhuapl.edu" class="auth_mail} ; K.P. Hand^g ; ^{Kevin.P.Hand@jpl.nasa.gov" class="auth_mail} ; T.A. Nordheimⁱ ; ^{Tan2@mssl.ucl.ac.uk" class="auth_mail} ; N. Krupp^b ; ^{krupp@mps.mpg.de" class="auth_mail} ; D.G. Mitchell^a ; ^{Donald.g.mitchell@jhuapl.edu" class="auth_mail}
• 关键词：Saturn ; satellites ; Saturn ; magnetosphere ; Satellites ; general
• 刊名：Icarus
• 出版年：15 May, 2014
• 年：2014
• 卷：234
• 期：Complete
• 页码：155-161
• 全文大小：1306 K

文摘

We have modeled an electron precipitation pattern expected on Mimas, Tethys, and Dione, using two different approaches. In the first approach, we adapt a previously developed model to compute an integrated energy flux into the surfaces of Mimas, Tethys, and Dione. This is a guiding-center, bounce-averaged model. In the second approach, we track individual particles in an electromagnetic field for an inert or slightly magnetized satellite. This second approach allows us to include the effects of electron pitch angle and gyrophase on the weathering pattern. Both methods converge on an enhanced dose pattern on each satellite鈥檚 leading hemisphere that is lens-shaped. We also present mission-averaged electron energy spectra obtained near these satellites by Cassini鈥檚 Magnetosphere Imaging Instrument (MIMI). These data are interpreted using our current understanding of both the environment and the instrument鈥檚 response. Fits to the data are integrated to find an energy flux into each satellite鈥檚 surface, as a function of longitude and latitude. Using positions on the moon accessible to energetic electrons from the modeling and the integrated energy flux based on data, we find lens patterns that fall off with increasing moon latitude. The predicted patterns are qualitatively consistent with some but not all of the optical observations made of these hemispheres.