Journal article
Cassini observations of ion and electron beams at Saturn and their relationship to infrared auroral arcs
Journal of geophysical research. Space physics, Vol.117(A1), A01211
01/2012
DOI: 10.1029/2011JA017222
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.
Details
- Title: Subtitle
- Cassini observations of ion and electron beams at Saturn and their relationship to infrared auroral arcs
- Creators
- S. V. Badman - Institute of Space and Astronautical ScienceN. Achilleos - University College LondonC. S. Arridge - University College LondonK. H. Baines - University of Wisconsin–MadisonR. H. Brown - University of ArizonaE. J. Bunce - University of LeicesterA. J. Coates - University College LondonS. W. H. Cowley - University of LeicesterM. K. Dougherty - Imperial College LondonM. Fujimoto - Institute of Space and Astronautical ScienceG. Hospodarsky - University of IowaS. Kasahara - Institute of Space and Astronautical ScienceT. Kimura - Institute of Space and Astronautical ScienceH. Melin - University of LeicesterD. G. Mitchell - Johns Hopkins University Applied Physics LaboratoryT. Stallard - University of LeicesterC. Tao - Institute of Space and Astronautical Science
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.117(A1), A01211
- Publisher
- Amer Geophysical Union
- DOI
- 10.1029/2011JA017222
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 12
- Grant note
- ST/H002480/1; ST/G002223/1; PP/E001130/1 / STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) ST/H00260X/1 / STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) CAPS ELS ESA via UK Space Agency CAPS ELS science at MSSL-UCL by STFC ISSI International Team PP/E001076/1 / Science and Technology Facilities Council; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) PP/D00084X/1 / UK Space Agency 1415150 / NASA; National Aeronautics & Space Administration (NASA) Jet Propulsion Laboratory
- Language
- English
- Date published
- 01/2012
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455558802771
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