General Earth and Planetary Sciences; Geophysics; Ganymede; Juno; Jupiter; Hubble Space Telescope; aurora
Abstract :
[en] We report results of Hubble Space Telescope observations from Ganymede's orbitally trailing side which were taken around the flyby of the Juno spacecraft on 7 June 2021. We find that Ganymede's northern and southern auroral ovals alternate in brightness such that the oval facing Jupiter's magnetospheric plasma sheet is brighter than the other one. This suggests that the generator that powers Ganymede's aurora is the momentum of the Jovian plasma sheet north and south of Ganymede's magnetosphere. Magnetic coupling of Ganymede to the plasma sheet above and below the moon causes asymmetric magnetic stresses and electromagnetic energy fluxes ultimately powering the auroral acceleration process. No clear statistically significant timevariability of the auroral emission on short time scales of 100s could be resolved. We show that electron energy fluxes of several tens of mW m−2 are required for its OI 1,356 Å emission making Ganymede a very poor auroral emitter.
Research Center/Unit :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Saur, Joachim ; Institute of Geophysics and Meteorology University of Cologne Cologne Germany
Duling, Stefan ; Institute of Geophysics and Meteorology University of Cologne Cologne Germany
Wennmacher, Alexandre ; Institute of Geophysics and Meteorology University of Cologne Cologne Germany
Willmes, Clarissa ; Institute of Geophysics and Meteorology University of Cologne Cologne Germany
Roth, Lorenz ; School of Electrical Engineering KTH, Royal Institute of Technology Stockholm Sweden
Strobel, Darrell F. ; Johns Hopkins University Baltimore MD USA
Allegrini, Frédéric ; Southwest Research Institute San Antonio TX USA ; Department of Physics and Astronomy University of Texas at San Antonio San Antonio TX USA
Bagenal, Fran ; University of Colorado Boulder CO USA
Bolton, Scott J. ; Southwest Research Institute San Antonio TX USA
Bonfond, Bertrand ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Clark, George ; Applied Physics Laboratory Johns Hopkins University Laurel MD USA
Gladstone, Randy ; Southwest Research Institute San Antonio TX USA ; Department of Physics and Astronomy University of Texas at San Antonio San Antonio TX USA
Greathouse, Thomas K. ; Southwest Research Institute San Antonio TX USA
Grodent, Denis ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Hansen, Candice J. ; Planetary Science Institute Tucson AZ USA
Kurth, William S. ; Department of Physics and Astronomy University of Iowa Iowa City IA USA
Orton, Glenn S. ; Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA
Retherford, Kurt D. ; Southwest Research Institute San Antonio TX USA ; Department of Physics and Astronomy University of Texas at San Antonio San Antonio TX USA
Rymer, Abigail M. ; Applied Physics Laboratory Johns Hopkins University Laurel MD USA
Sulaiman, Ali H. ; Department of Physics and Astronomy University of Iowa Iowa City IA USA
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