ORBi: Jacobsen Sven - The Io Footprint Morphology

Reference : The Io Footprint Morphology


	Document type :	Scientific congresses and symposiums : Unpublished conference
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
	To cite this reference:	http://hdl.handle.net/2268/104431

Title :	The Io Footprint Morphology
Language :	English
Author, co-author :	Jacobsen, Sven [ > > ]
	Saur, Joachim [ > > ]
	Neubauer, F. M. [ > > ]
	Bonfond, Bertrand [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
	Gérard, Jean-Claude [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO) >]
	Grodent, Denis [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
Publication date :	23-Sep-2008
On invitation :	No
Audience :	International
Event name :	European Planetary Science Congress 2008
Event date :	du 21 septembre 2008 au 26 septembre 2008
Event organizer :	Europlanet
Event place (city) :	Münster
Event country :	Allemagne
Keywords :	[en] Io footprint
Abstract :	[en] The innermost Galilean moon Io is embedded in a dense plasma torus. It disturbs the flow of the corotating torus plasma and generates MHD waves. Especially the Alfv ́ n e mode, which carries electric currents along the magnetic field, is responsible for the famous Io footprint in the Jo- vian aurora. The Alfv ́ n waves are partly reflected at plasma e density gradients e.g. at the torus edges and form a compli- cated wave pattern. The footprint morphology in the Jovian aurora displays this pattern. Besides the main spot feature, a trailing wake extending over up to 100 degrees and occa- sionally occurring multiple spots indicating reflections have been identified. The intensity, the occurrence of multiple spots and the inter-spot distances have been found to vary strongly [1]. Io is moving up and down in the plasma torus confined to the centrifugal equator. It interacts with a dense plasma when located in the torus center and considerably thinner plasma at the torus flanks. The incoming plasma density controls the interaction strength and wave amplitude. This primar- ily leads to a relationship between the footprint brightness and Io’s centrifugal latitude [1]. However, it has also been shown that the reflection angle is strongly depending on the wave amplitude due to nonlinear effects [2]. This has an impact on the inter-spot distances. On the other hand this parameter is also directly affected when Io changes its posi- tion in the plasma torus. To deconvolve this system we present the results of our 3D MHD simulations showing the influence of Io’s centrifugal latitude and nonlinearities on the footprint morphology par- ticularly on the number of spots and inter-spot distances. We observe interference phenomena leading to locally en- hanced or reduced footprint brightness. We also discuss the recently observed leading spot feature [3].
Target :	Researchers ; Professionals
Permalink :	http://hdl.handle.net/2268/104431

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