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AGU: Journal of Geophysical Research, Space Physics

 

Keywords

  • aurora
  • magnetosphere
  • acceleration processes

Index Terms

  • Magnetospheric Physics: Auroral phenomena
  • Magnetospheric Physics: Field-aligned currents and current systems
  • Magnetospheric Physics: Magnetospheric configuration and dynamics
  • Magnetospheric Physics: Magnetosphere/ionosphere interactions
  • Magnetospheric Physics: Instruments and techniques
Abstract
Cited By (10)
 

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, A10212, 13 PP., 2009
doi:10.1029/2009JA014401

An auroral oval at the footprint of Saturn's kilometric radio sources, colocated with the UV aurorae

L. Lamy

LESIA, Observatoire de Paris, UPMC, CNRS, Université Paris Diderot, Meudon, France

Space and Atmospheric Physics Group, Blackett Laboratory, Imperial College London, London, UK

B. Cecconi

LESIA, Observatoire de Paris, UPMC, CNRS, Université Paris Diderot, Meudon, France

R. Prangé

LESIA, Observatoire de Paris, UPMC, CNRS, Université Paris Diderot, Meudon, France

P. Zarka

LESIA, Observatoire de Paris, UPMC, CNRS, Université Paris Diderot, Meudon, France

J. D. Nichols

Department of Physics and Astronomy, University of Leicester, Leicester, UK

J. T. Clarke

Center for Space Physics, Boston University, Boston, Massachusetts, USA

Similarly to other magnetized planets, Saturn displays auroral emissions generated by accelerated electrons gyrating around high-latitude magnetic field lines. They mainly divide in ultraviolet (UV) and infrared (IR) aurorae, excited by electron collisions with the upper atmosphere, and Saturn's kilometric radiation (SKR), radiated from higher altitudes by electron-wave resonance. Whereas spatially resolved UV and IR images of atmospheric aurorae reveal a continuous auroral oval around each pole, the SKR source locus was only indirectly constrained by the Voyager radio experiment to a limited local time (LT) range on the morningside, leading to interpretation of the SKR modulation as a fixed flashing light. Here, we present resolved SKR maps derived from the Cassini Radio and Plasma Wave Science (RPWS) experiment using goniopolarimetric techniques. We observe radio sources all around the planet, organized along a high-latitude continuous auroral oval. Observations of the Hubble Space Telescope obtained in January 2004 and January 2007 have been compared to simultaneous and averaged Cassini-RPWS measurements, revealing that SKR and UV auroral ovals are very similar, both significantly enhanced on the dawnside. These results imply that the SKR and atmospheric aurorae are triggered by the same populations of energetic electron beams, requiring a unified model of particle acceleration and precipitation on Saturn.

Received 28 April 2009; accepted 20 July 2009; published 24 October 2009.

Citation: Lamy, L., B. Cecconi, R. Prangé, P. Zarka, J. D. Nichols, and J. T. Clarke (2009), An auroral oval at the footprint of Saturn's kilometric radio sources, colocated with the UV aurorae, J. Geophys. Res., 114, A10212, doi:10.1029/2009JA014401.

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