Mapping the Brightness of Ganymede's Ultraviolet Aurora Using Hubble Space Telescope Observations

[en] We analyze Hubble Space Telescope observations of Ganymede made with the Space Telescope Imaging Spectrograph between 1998 and 2017 to generate a brightness map of Ganymede's oxygen emission at 1,356 Å. Our Mercator projected map demonstrates that the brightness along Ganymede's northern and southern auroral ovals strongly varies with longitude. To quantify this variation around Ganymede, we investigate the brightness averaged over 36°-wide longitude corridors centered around the sub-Jovian (0° W), leading (90° W), anti-Jovian (180° W), and trailing (270° W) central longitudes. In the northern hemisphere, the brightness of the auroral oval is 3.7 ± 0.4 times lower in the sub-Jovian and anti-Jovian corridors compared to the trailing and leading corridors. The southern oval is overall brighter than the northern oval, and only 2.5 ± 0.2 times fainter on the sub- and anti-Jovian corridors compared to the trailing and leading corridors. This demonstrates that Ganymede's auroral ovals are strongly structured in auroral crescents on the leading side (plasma downstream side) and on the trailing side (plasma upstream side). We also find that the brightness is not symmetric with respect to the 270° meridian, but shifted by ∼20° towards the Jovian-facing hemisphere. Our map will be useful for subsequent studies to understand the processes that generate the aurora in Ganymede's non-rotationally driven, sub-Alfvénic magnetosphere.

Research Center/Unit :

STAR - Space sciences, Technologies and Astrophysics Research - ULiège

Disciplines :

Space science, astronomy & astrophysics

Author, co-author :

Marzok, Alexander; Institute of Geophysics and Meteorology, University of Cologne, Cologne, Germany

Schlegel, Stehpan ; Institute of Geophysics and Meteorology, University of Cologne, Cologne, Germany

Saur, Joachim ; Institute of Geophysics and Meteorology, University of Cologne, Cologne, Germany

Roth, Lorenz ; School of Electrical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden

Grodent, Denis ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)

Strobel, Darrell F. ; Department of Earth and Planetary Science, and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, United States

Retherford, Kurt D. ; Southwest Research Institute, San Antonio, United States ; University of Texas at San Antonio, San Antonio, United States

Language :

English

Title :

Mapping the Brightness of Ganymede's Ultraviolet Aurora Using Hubble Space Telescope Observations

Publication date :

June 2022

Journal title :

Journal of Geophysical Research. Planets

ISSN :

2169-9097

eISSN :

2169-9100

Publisher :

John Wiley and Sons Inc

Volume :

127

Issue :

Peer reviewed :

Peer Reviewed verified by ORBi

Additional URL :

https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JE007256

Funding text :

This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 884711). Open access funding enabled and organized by Projekt DEAL.

Data Set :

https://doi.org/10.1029/2022JE007256

Commentary :

Accepted for Publication in Journal of Geophysical Research (Planets)

Available on ORBi :

since 17 May 2023

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