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Formation of Saturn's ring spokes by lightning-induced electron beams

Jones, GH; Krupp, N; Kruger, H; Roussos, E; Ip, WH; Mitchell, DG; Krimigis, SM; ... McAndrews, HJ; + view all (2006) Formation of Saturn's ring spokes by lightning-induced electron beams. Geophysical Research Letters , 33 (21) , Article L21202. 10.1029/2006GL028146. Green open access

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Abstract

Spokes are near-linear markings sometimes visible on Saturn's rings. They are widely accepted as being electrostatically-levitated sheets of similar to 0.6 micron-radius charged grains. Previously-suggested causes of the grains' charging do not agree with all spoke characteristics, which include their rapid generation, localized formation primarily in Saturn's midnight-dawn sector, the seasonality of their apparitions, and, crucially, their morphologies. We contend that spokes are caused by lightning-induced electron beams striking the rings, at locations magnetically-connected to thunderstorms. This view is supported by a semi-quantitative spoke morphology simulation. Spokes' formation locations are further controlled by Saturn's ionospheric density, which reaches a near-dawn minimum where electron beams can most easily propagate to the rings. The beams may generate observed X-ray emission, supply particles to Saturn's radiation belts, and over time will modify the rings' constituents. Finally, we report Cassini MIMI instrument observations of an electron burst which displays some characteristics expected of a lightning-induced event.

Type: Article
Title: Formation of Saturn's ring spokes by lightning-induced electron beams
Open access status: An open access version is available from UCL Discovery
DOI: 10.1029/2006GL028146
Publisher version: http://dx.doi.org/10.1029/2006GL028146
Language: English
Additional information: Copyright 2006 by the American Geophysical Union
Keywords: X-ray-emission, B-ring, Runaway Electrons, Sprites, System, Discharge, Plasma
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/9651
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