Excitation of the ganymede ultraviolet aurora

Aharon Eviatar*, Darrell F. Strobel, Brian C. Wolven, Paul D. Feldman, Melissa A. Mcgrath, Donald J. Williams

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We analyze the ultraviolet aurorae observed on Ganymede by means of the Hubble Space Telescope and compare them to similar phenomena on Earth. We find that the tenuous nature of Ganymede's atmosphere precludes excitation of the aurora by high-energy electrons and requires a local acceleration mechanism. We propose the following as plausible mechanisms for generating both the continuous background emission and the intense auroral bright spots: 1. Birkeland-type currents and associated magnetic field-aligned electric fields. 2. The stochastic heating of plasma electrons by the Landau damping of electron plasma oscillations generated by precipitated energetic electrons. We conclude that the electron density in the bright regions may attain local values as high as 105 cm-3.

Original languageEnglish
Pages (from-to)1013-1019
Number of pages7
JournalAstrophysical Journal
Volume555
Issue number2 PART 1
DOIs
StatePublished - 10 Jul 2001

Keywords

  • Planets and satellites: individual (Ganymede)
  • Plasmas
  • Ultraviolet: solar system

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