The auroral footprint of Enceladus on Saturn |
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Authors: | Pryor Wayne R Rymer Abigail M Mitchell Donald G Hill Thomas W Young David T Saur Joachim Jones Geraint H Jacobsen Sven Cowley Stan W H Mauk Barry H Coates Andrew J Gustin Jacques Grodent Denis Gérard Jean-Claude Lamy Laurent Nichols Jonathan D Krimigis Stamatios M Esposito Larry W Dougherty Michele K Jouchoux Alain J Stewart A Ian F McClintock William E Holsclaw Gregory M Ajello Joseph M Colwell Joshua E Hendrix Amanda R Crary Frank J Clarke John T Zhou Xiaoyan |
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Affiliation: | Science Department, Central Arizona College, Coolidge, Arizona 85128, USA. |
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Abstract: | Although there are substantial differences between the magnetospheres of Jupiter and Saturn, it has been suggested that cryovolcanic activity at Enceladus could lead to electrodynamic coupling between Enceladus and Saturn like that which links Jupiter with Io, Europa and Ganymede. Powerful field-aligned electron beams associated with the Io-Jupiter coupling, for example, create an auroral footprint in Jupiter's ionosphere. Auroral ultraviolet emission associated with Enceladus-Saturn coupling is anticipated to be just a few tenths of a kilorayleigh (ref. 12), about an order of magnitude dimmer than Io's footprint and below the observable threshold, consistent with its non-detection. Here we report the detection of magnetic-field-aligned ion and electron beams (offset several moon radii downstream from Enceladus) with sufficient power to stimulate detectable aurora, and the subsequent discovery of Enceladus-associated aurora in a few per cent of the scans of the moon's footprint. The footprint varies in emission magnitude more than can plausibly be explained by changes in magnetospheric parameters--and as such is probably indicative of variable plume activity. |
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