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Title: Cassini observations of ion and electron beams at Saturn and their relationship to infrared auroral arcs
Authors: Badman, S.V.
Achilleos, N.
Arridge, C.S.
Baines, K.H.
Brown, R.H.
Bunce, E.J.
Coates, A.J.
Cowley, S.W.H.
Dougherty, M.K.
Fujimoto, M.
Hospodarsky, G.
Kasahara, S.
Kimura, T.
Melin, H.
Mitchell, D.G.
Stallard, T.S.
Tao, C.
First Published: 21-Jan-2012
Publisher: American Geophysical Union (AGU)
Citation: Journal of Geophysical Research Space Physics, 2012, 117, A01211 (12).
Abstract: We present Cassini Visual and Infrared Mapping Spectrometer observations of infrared auroral emissions from the noon sector of Saturn's ionosphere revealing multiple intense auroral arcs separated by dark regions poleward of the main oval. The arcs are interpreted as the ionospheric signatures of bursts of reconnection occurring at the dayside magnetopause. The auroral arcs were associated with upward field-aligned currents, the magnetic signatures of which were detected by Cassini at high planetary latitudes. Magnetic field and particle observations in the adjacent downward current regions showed upward bursts of 100–360 keV light ions in addition to energetic (hundreds of keV) electrons, which may have been scattered from upward accelerated beams carrying the downward currents. Broadband, upward propagating whistler waves were detected simultaneously with the ion beams. The acceleration of the light ions from low altitudes is attributed to wave-particle interactions in the downward current regions. Energetic (600 keV) oxygen ions were also detected, suggesting the presence of ambient oxygen at altitudes within the acceleration region. These simultaneous in situ and remote observations reveal the highly energetic magnetospheric dynamics driving some of Saturn's unusual auroral features. This is the first in situ identification of transient reconnection events at regions magnetically conjugate to Saturn's magnetopause.
DOI Link: 10.1029/2011JA017222
ISSN: 0148-0227
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2012 by the American Geophysical Union. Deposited with reference to the publisher's archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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