Journal article
Discrete and broadband electron acceleration in Jupiter's powerful aurora
Nature (London), Vol.549(7670), pp.66-69
09/07/2017
DOI: 10.1038/nature23648
PMID: 28880294
Abstract
The most intense auroral emissions from Earth's polar regions, called discrete for their sharply defined spatial configurations, are generated by a process involving coherent acceleration of electrons by slowly evolving, powerful electric fields directed along the magnetic field lines that connect Earth's space environment to its polar regions(1,2). In contrast, Earth's less intense auroras are generally caused by wave scattering of magnetically trapped populations of hot electrons (in the case of diffuse aurora) or by the turbulent or stochastic downward acceleration of electrons along magnetic field lines by waves during transitory periods (in the case of broadband or Alfvenic aurora)(3,4). Jupiter's relatively steady main aurora has a power density that is so much larger than Earth's that it has been taken for granted that it must be generated primarily by the discrete auroral process(5-7). However, preliminary in situ measurements of Jupiter's auroral regions yielded no evidence of such a process(8-10). Here we report observations of distinct, high-energy, downward, discrete electron acceleration in Jupiter's auroral polar regions. We also infer upward magnetic-field-aligned electric potentials of up to 400 kiloelectronvolts, an order of magnitude larger than the largest potentials observed at Earth(11). Despite the magnitude of these upward electric potentials and the expectations from observations at Earth, the downward energy flux from discrete acceleration is less at Jupiter than that caused by broadband or stochastic processes, with broadband and stochastic characteristics that are substantially different from those at Earth.
Details
- Title: Subtitle
- Discrete and broadband electron acceleration in Jupiter's powerful aurora
- Creators
- B. H. Mauk - Johns Hopkins University Applied Physics LaboratoryD. K. Haggerty - Johns Hopkins University Applied Physics LaboratoryC. P. Aranicas - Johns Hopkins UniversityG. Clark - Johns Hopkins University Applied Physics LaboratoryP. Kollmann - Johns Hopkins University Applied Physics LaboratoryA. M. Rymer - Johns Hopkins University Applied Physics LaboratoryS. J. Bolton - Southwest Research InstituteS. M. Levin - Jet Propulsion LaboratoryA. Adriani - Institute for Space Astrophysics and PlanetologyF. Allegrini - Southwest Research InstituteF. Bagenal - University of Colorado BoulderB. Bonfond - University of LiègeJ. E. P. Connerney - Goddard Space Flight CenterG. R. Gladstone - Southwest Research InstituteW. S. Kurth - University of IowaD. J. McComas - Southwest Research InstituteP. Valek - Southwest Research Institute
- Resource Type
- Journal article
- Publication Details
- Nature (London), Vol.549(7670), pp.66-69
- DOI
- 10.1038/nature23648
- PMID
- 28880294
- NLM abbreviation
- Nature
- ISSN
- 0028-0836
- eISSN
- 1476-4687
- Publisher
- Springer Nature
- Number of pages
- 6
- Grant note
- NASA's New Frontiers Program Southwest Research Institute
- Language
- English
- Date published
- 09/07/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455362802771
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