Journal article
Energetic Proton Acceleration Associated With Io's Footprint Tail
Geophysical research letters, Vol.47(24), e2020GL090839
12/28/2020
DOI: 10.1029/2020GL090839
Abstract
Observations of energetic charged particles associated with Io's footprint (IFP) tail, and likely within or very near the Main Alfvén Wing, during Juno's 12th perijove (PJ) crossing show evidence of intense proton acceleration by wave‐particle heating. Measurements made by Juno/JEDI reveal proton characteristics that include pitch angle distributions concentrated along the upward loss cone, broad energy distributions that span ~50 keV to 1 MeV, highly structured temporal/spatial variations in the particle intensities, and energy fluxes as high as ~100 mW/m2. Simultaneous measurements of the plasma waves and magnetic field suggest the presence of ion cyclotron waves and transverse Alfvénic fluctuations. We interpret the proton observations as upgoing conics likely accelerated via resonant interactions with ion cyclotron waves. These observations represent the first measurements of ion conics associated with moon‐magnetosphere interactions, suggesting energetic ion acceleration plays a more important role in the IFP tail region than previously considered.
Plain Language Summary
NASA's Juno spacecraft orbits Jupiter's polar region and makes direct measurements of the fields and particles that are responsible for creating Jupiter's powerful auroras. In this article, we present new observations that show intense proton acceleration occurring at altitudes near the auroral emissions created by the interaction between Jupiter's moon Io and the surrounding plasma and magnetic field environment. These unique observations provide clues on how particles are being accelerated and will help constrain particle acceleration theories.
Key Points
Juno's likely crossing of Io's Main Alfvén Wing (MAW) during PJ12 reveals evidence of transverse ion acceleration
Observations suggest wave‐particle interactions with ion cyclotron waves as the favored acceleration mechanism; however, Alfvén acceleration was not ruled out
Ion conics generated in Io's footprint tail or near the MAW are more intense and energetic than observed in other auroral regions
Details
- Title: Subtitle
- Energetic Proton Acceleration Associated With Io's Footprint Tail
- Creators
- G. Clark - Johns Hopkins University Applied Physics LaboratoryB. H. Mauk - Johns Hopkins University Applied Physics LaboratoryP. Kollmann - Johns Hopkins University Applied Physics LaboratoryJ. R. Szalay - Princeton UniversityA. H. Sulaiman - University of IowaD. J. Gershman - Goddard Space Flight CenterJ. Saur - University of CologneS. Janser - University of CologneK. Garcia-Sage - Goddard Space Flight CenterT. Greathouse - Southwest Research InstituteC. Paranicas - Johns Hopkins University Applied Physics LaboratoryF. Allegrini - Southwest Research InstituteF. Bagenal - Laboratory for Atmospheric and Space PhysicsS. J. Bolton - Southwest Research InstituteJ. E. P. Connerney - Goddard Space Flight CenterR. W. Ebert - Southwest Research InstituteG. Hospodarsky - University of IowaD. Haggerty - Johns Hopkins University Applied Physics LaboratoryV. Hue - Southwest Research InstituteM. Imai - National Institute of Technology, Niihama CollegeS. Kotsiaros - National Space Institute Measurement and Instrumentation Systems, DTUD. J. McComas - Princeton UniversityA. Rymer - Johns Hopkins University Applied Physics LaboratoryJ. Westlake - Johns Hopkins University Applied Physics Laboratory
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.47(24), e2020GL090839
- DOI
- 10.1029/2020GL090839
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 10
- Grant note
- NASA (699041X)
- Language
- English
- Date published
- 12/28/2020
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455541902771
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