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AGU: Geophysical Research Letters

 

Keywords

  • auroral emissions
  • electron precipitation
  • energetic particles

Index Terms

  • Magnetospheric Physics: Auroral phenomena
  • Magnetospheric Physics: Magnetosphere/ionosphere interactions
  • Magnetospheric Physics: Energetic particles: precipitating
  • Magnetospheric Physics: Planetary magnetospheres

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L07101, 5 PP., 2009
doi:10.1029/2009GL037857

Equatorward diffuse auroral emissions at Jupiter: Simultaneous HST and Galileo observations

A. Radioti

Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique et de Géophysique, Université de Liège, Liège, Belgium

A. T. Tomás

GeoForschungsZentrum, Potsdam, Germany

D. Grodent

Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique et de Géophysique, Université de Liège, Liège, Belgium

J.‐C. Gérard

Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique et de Géophysique, Université de Liège, Liège, Belgium

J. Gustin

Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique et de Géophysique, Université de Liège, Liège, Belgium

B. Bonford

Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique et de Géophysique, Université de Liège, Liège, Belgium

N. Krupp

Max‐Planck‐Institut für Sonnensystemforschung, Katlenburg‐Lindau, Germany

J. Woch

Max‐Planck‐Institut für Sonnensystemforschung, Katlenburg‐Lindau, Germany

J. D. Menietti

Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa, USA

We study the auroral emissions equatorward of the main oval based on Hubble Space Telescope (HST) observations of both Jovian hemispheres on September 20, 1997. On the same day, Galileo observed changes in the electron pitch angle distribution between the inner and middle magnetosphere (PAD boundary), indicative of electron diffusion. This region, magnetically maps to the equatorward diffuse emissions on both hemispheres. Whistler mode waves, observed simultaneously, can scatter electrons into the loss cone and lead to electron precipitation in the ionosphere. Based on simultaneous HST FUV and Galileo wave and electron data we test the conditions for electron scattering by whistler mode waves and derive the energy flux precipitated in the ionosphere. The comparison of the derived precipitation energy flux with the observed auroral brightness indicates that the energy contained in the PAD boundary can account for the auroral emissions.

Received 26 February 2009; accepted 4 March 2009; published 2 April 2009.

Citation: Radioti, A., A. T. Tomás, D. Grodent, J.‐C. Gérard, J. Gustin, B. Bonford, N. Krupp, J. Woch, and J. D. Menietti (2009), Equatorward diffuse auroral emissions at Jupiter: Simultaneous HST and Galileo observations, Geophys. Res. Lett., 36, L07101, doi:10.1029/2009GL037857.

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