Generation of the Jovian hectometric radiation: First lessons from Juno

P. Louarn, F. Allegrini, D. J. McComas, P. W. Valek, W. S. Kurth, N. André, F. Bagenal, S. Bolton, J. Connerney, R. W. Ebert, M. Imai, S. Levin, J. R. Szalay, S. Weidner, R. J. Wilson, J. L. Zink

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Using Juno plasma and wave and magnetic observations (JADE and Waves and MAG instruments), the generation mechanism of the Jovian hectometric radio emission is analyzed. It is shown that suitable conditions for the cyclotron maser instability (CMI) are observed in the regions of the radio sources. Pronounced loss cone in the electron distributions are likely the source of free energy for the instability. The theory reveals that sufficient growth rates are obtained from the distribution functions that are measured by the JADE-Electron instrument. The CMI would be driven by upgoing electron populations at 5–10 keV and 10–30° pitch angle, the amplified waves propagating at 82°–87° from the B field, a fraction of a percent above the gyrofrequency. Typical e-folding times of 10−4 s are obtained, leading to an amplification path of ~1000 km. Overall, this scenario for generation of the Jovian hectometric waves differs significantly from the case of the auroral kilometric radiation at Earth.

Original languageEnglish (US)
Pages (from-to)4439-4446
Number of pages8
JournalGeophysical Research Letters
Volume44
Issue number10
DOIs
StatePublished - May 28 2017

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

Keywords

  • Jupiter
  • magnetosphere
  • radio waves

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    Louarn, P., Allegrini, F., McComas, D. J., Valek, P. W., Kurth, W. S., André, N., Bagenal, F., Bolton, S., Connerney, J., Ebert, R. W., Imai, M., Levin, S., Szalay, J. R., Weidner, S., Wilson, R. J., & Zink, J. L. (2017). Generation of the Jovian hectometric radiation: First lessons from Juno. Geophysical Research Letters, 44(10), 4439-4446. https://doi.org/10.1002/2017GL072923