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A plasmapause‐like density boundary at high latitudes in Saturn's magnetosphere
Author(s) -
Gurnett D. A.,
Persoon A. M.,
Kopf A. J.,
Kurth W. S.,
Morooka M. W.,
Wahlund J.E.,
Khurana K. K.,
Dougherty M. K.,
Mitchell D. G.,
Krimigis S. M.,
Krupp N.
Publication year - 2010
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 - 10.1029/2010gl044466
Subject(s) - magnetosphere , plasmasphere , physics , saturn , planet , boundary (topology) , geophysics , latitude , magnetosphere of saturn , magnetic field , astrophysics , computational physics , magnetopause , astronomy , mathematical analysis , mathematics , quantum mechanics
Here we report the discovery of a well‐defined plasma density boundary at high latitudes in Saturn's magnetosphere. The boundary separates a region of relatively high density at L less than about 8 to 15 from a region with densities nearly three orders of magnitude lower at higher L values. Magnetic field measurements show that strong field‐aligned currents, probably associated with the aurora, are located just inside the boundary. Analyses of the anisotropy of energetic electrons show that the magnetic field lines are usually closed inside the boundary and open outside the boundary, although exceptions sometimes occur. The location of the boundary is also modulated at the ∼10.6 to 10.8 hr rotational period of the planet. Many of these characteristics are similar to those predicted by Brice and Ioannidis for the plasmapause at a strongly magnetized, rapidly rotating planet such as Saturn.