The multiple spots of the Ganymede auroral footprint

[en] The interaction between the moons and the magnetosphere of giant planets sometimes gives rise to auroral signatures in the planetary ionosphere, called the satellite footprints. So far, footprints have been detected for Io, Europa, Ganymede, and Enceladus. These footprints are usually seen as single spots. However, the Io footprint, the brightest one, displays a much more complex morphology made of at least three different spots and an extended tail. Here we present Hubble Space Telescope FUV images showing evidence for a second spot in the Ganymede footprint. The spots separation distance changes as Ganymede moves latitudinally in the plasma sheet, as is seen for the Io footprint. This indicates that the processes identified at Io are universal. Moreover, for similar Ganymede System III longitudes, the distance may also vary significantly with time, indicating changes in the plasma sheet density. We identified a rapid evolution of this distance 8 days after the detection of a volcanic outburst at Io, suggesting that such auroral observations could be used to estimate the plasma density variations at Ganymede.

Research Center/Unit :

LiSRI - Liège Space Research Institute - ULiège

Disciplines :

Space science, astronomy & astrophysics

Author, co-author :

Bonfond, Bertrand ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)

Hess, Sébastien; Université de Versailles Saint-Quentin > LATMOS

Bagenal, Fran; University of Colorado at Boulder - CU > LASP

Gérard, Jean-Claude ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)

Grodent, Denis ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Physique des atmosphères et des environnements planétaires

Radioti, Aikaterini ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)

Gustin, Jacques ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Physique des atmosphères et des environnements planétaires

Clarke, John T.; Boston University > Center for Space Physics

Language :

English

Title :

The multiple spots of the Ganymede auroral footprint

Publication date :

04 October 2013

Journal title :

Geophysical Research Letters

ISSN :

0094-8276

eISSN :

1944-8007

Publisher :

American Geophysical Union, Washington, United States - District of Columbia

Volume :

Peer reviewed :

Peer Reviewed verified by ORBi

Funders :

F.R.S.-FNRS - Fonds de la Recherche Scientifique
BELSPO - SPP Politique scientifique - Service Public Fédéral de Programmation Politique scientifique

Available on ORBi :

since 01 October 2013

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