Article (Scientific journals)
Discrete and broadband electron acceleration in Jupiter's powerful aurora
Mauk, B. H.; Haggerty, D. K.; Paranicas, C. et al.
2017In Nature, 549, p. 66-69
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Keywords :
Jupiter; aurora; Juno
Abstract :
[en] 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. 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 Alfvénic aurora). 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. However, preliminary in situ measurements of Jupiter's auroral regions yielded no evidence of such a process. 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. 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.
Research center :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Mauk, B. H.;  The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
Haggerty, D. K.;  The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
Paranicas, C.;  The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
Clark, G.;  The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
Kollmann, P.;  The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
Rymer, A. M.;  The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
Bolton, S. J.;  Southwest Research Institute, San Antonio, Texas, USA
Levin, S. M.;  Jet Propulsion Laboratory, Pasadena, California, USA
Adriani, A.;  Instituto Nazionale di Astrofisica-Instituo di Astofisica e Planetologia Spaziali, Roma, Italy
Allegrini, F.;  Southwest Research Institute, San Antonio, Texas, USA ; Physics and Astronomy Department, University of Texas at San Antonio, San Antonio, Texas, USA
Bagenal, F.;  University of Colorado, Boulder, Colorado, USA
Bonfond, Bertrand  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Connerney, J. E. P.;  NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
Gladstone, G. R.;  Southwest Research Institute, San Antonio, Texas, USA
Kurth, W. S.;  University of Iowa, Iowa City, Iowa, USA
McComas, D. J.;  Southwest Research Institute, San Antonio, Texas, USA ; Princeton University, Princeton, New Jersey, USA
Valek, P.;  Southwest Research Institute, San Antonio, Texas, USA)
More authors (7 more) Less
Language :
English
Title :
Discrete and broadband electron acceleration in Jupiter's powerful aurora
Publication date :
01 September 2017
Journal title :
Nature
ISSN :
0028-0836
eISSN :
1476-4687
Publisher :
Nature Publishing Group, London, United Kingdom
Volume :
549
Pages :
66-69
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 30 October 2017

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