Europlanet Science Congress 2021
Virtual meeting
13 – 24 September 2021
Europlanet Science Congress 2021
Virtual meeting
13 September – 24 September 2021
EPSC Abstracts
Vol. 15, EPSC2021-272, 2021
European Planetary Science Congress 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

A new framework to explain changes in Io's footprint tail electron fluxes in the Juno era

Jamey Szalay1, Frederic Allegrini2,3, Fran Bagenal4, Scott Bolton2, Bertrand Bonfond5, George Clark6, Jack Connerney7,8, Robert Ebert2,3, Vincent Hue2, David McComas1, Joachim Saur9, Ali Sulaiman10, and Robert Wilson4
Jamey Szalay et al.
  • 1Princeton University, Astrophysical Sciences, Princeton, United States of America (
  • 2Southwest Research Institute, San Antonio, TX, USA
  • 3Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
  • 4Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO, USA
  • 5Space Sciences, Technologies and Astrophysics Research Institute, LPAP, Université de Liège, Liège, Belgium
  • 6Johns Hopkins University Applied Physics Lab, Laurel, MD, USA
  • 7Space Research Corporation, Annapolis, MD, USA
  • 8Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 9Institute of Geophysics and Meteorology, University of Cologne, Cologne, Germany
  • 10Department of Physics and Astronomy, University of Iowa, IA, USA

Jupiter’s aurora is complex and dynamic, with a large number of distinct auroral features and regions generated by multiple phenomena. Of these features, Io’s auroral signature is one of the most persistent and identifiable aurora, with a rich observational history spanning decades of remote observations. Since Juno arrived at Jupiter, providing in-situ transits through flux tubes directly connected to Io’s auroral emissions, its diverse set of instruments have revealed an even more complex and dynamic picture of Io’s auroral interaction. In this presentation, we report on Juno observations of precipitating electron fluxes connected to 18 crossings of Io’s footprint tail aurora, over altitudes of 0.15 to 1.1 Jovian radii (RJ). We will highlight how the strength of precipitating electron fluxes is dominantly organized by “Io-Alfvén tail distance”, the angle along Io’s orbit between Io and an Alfvén wave trajectory connected to the tail aurora. We will discuss how these fluxes were best fit with an exponential as a function of down-tail extent with an e-folding distance of 21˚, the acceleration region altitude likely increases down-tail, and most of the parallel electron acceleration sustaining the tail aurora occurs above 1 RJ in altitude. Finally, we will highlight how Juno has likely transited Io’s Main Alfvén Wing fluxtube, observing a characteristically distinct signature with precipitating electron fluxes ~600 mW/m2 and an acceleration region extending as low as 0.4 RJ in altitude.

How to cite: Szalay, J., Allegrini, F., Bagenal, F., Bolton, S., Bonfond, B., Clark, G., Connerney, J., Ebert, R., Hue, V., McComas, D., Saur, J., Sulaiman, A., and Wilson, R.: A new framework to explain changes in Io's footprint tail electron fluxes in the Juno era, European Planetary Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-272,, 2021.

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