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Energetic Electron Pitch Angle Distributions During the Cassini Final Orbits
Author(s) -
Carbary J. F.,
Mitchell D. G.,
Kollmann P.,
Krupp N.,
Roussos E.,
Dougherty M. K.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2018gl077656
Subject(s) - titan (rocket family) , equator , physics , pitch angle , saturn , electron , enceladus , field line , magnetosphere , magnetic field , magnetosphere of saturn , spacecraft , geophysics , astrophysics , magnetopause , astronomy , latitude , planet , quantum mechanics
Abstract Pitch angle distributions (PADs) of very energetic electrons (110–365 keV) are examined during the ring‐grazing and proximal orbits of the Cassini spacecraft, from day 320 2016 (15 November) to day 257 2017 (14 September). These repeating orbits allowed a statistical evaluation of the PADs within the magnetopause on the nightside of Saturn. Along L ‐shells (i.e., equatorial crossing distances of magnetic field lines) near and outside that of Titan and north of the equator, the electron fluxes were unidirectionally field‐aligned going away from Saturn. Along L ‐shells inside Titan's and south of the equator, the electrons had bidirectional or pancake (trapping) PADs. This behavior suggests that the field lines within Titan's L ‐shell are generally closed, while those outside of that L ‐shell are generally open. This result strictly applies only to the nightside local times sampled during the final Cassini orbits, but one may infer a similar behavior at other times.