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

doi:10.1002/2017GL072923

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Generation of the Jovian hectometric radiation: First lessons from Juno

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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, …

Geophysical research letters, Vol.44(10), pp.4439-4446

05/28/2017

DOI: 10.1002/2017GL072923

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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. Key Points First detailed wave/particle investigation in a Jovian radio source, using JADE, Waves, and MAG Juno instruments Confirmation that the cyclotron maser instability is the generation mechanism Demonstration that the observed loss cone distributions provide sufficient growth rates to explain the wave amplification

Jupiter

magnetosphere

radio waves

Details

Title: Subtitle: Generation of the Jovian hectometric radiation: First lessons from Juno
Creators: P. Louarn - Institut de Recherche en Astrophysique et Planétologie
F. Allegrini - Southwest Research Institute
D. J. McComas - Southwest Research Institute
P. W. Valek - Southwest Research Institute
W. S. Kurth - University of Iowa
N. André - Institut de Recherche en Astrophysique et Planétologie
F. Bagenal - Laboratory for Atmospheric and Space Physics
S. Bolton - Southwest Research Institute
J. Connerney - Goddard Space Flight Center
R. W. Ebert - Southwest Research Institute
M. Imai - University of Iowa
S. Levin - Jet Propulsion Laboratory
J. R. Szalay - Southwest Research Institute
S. Weidner - Princeton University
R. J. Wilson - Laboratory for Atmospheric and Space Physics
J. L. Zink - Southwest Research Institute
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.44(10), pp.4439-4446
DOI: 10.1002/2017GL072923
ISSN: 0094-8276
eISSN: 1944-8007
Number of pages: 8
Grant note: NASA CNRS CNES
Language: English
Date published: 05/28/2017
Academic Unit: Physics and Astronomy
Record Identifier: 9984455362702771

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