| 英文摘要 | We report the first in situ observations of electron measurements at a Europa footprint tail (FPT) crossing in the auroral region. During its 12th science perijove pass, Juno crossed magnetic field lines connected to Europa's FPT. We find that electrons in the range ~0.4 to ~25 keV, with a characteristic energy of 3.6 ± 0.5 keV, precipitate into Jupiter's atmosphere to create the footprint aurora. The energy flux peaks at ~36 mW/m2, while the peak ultraviolet (UV) brightness is estimated at 37 kR. We estimate the peak electron density and temperature to be 17.3 cm−3 and 1.8 ± 0.1 keV, respectively. Using magnetic flux shell mapping, we estimate that the radial width of the interaction at Europa's orbit spans roughly 3.6 ± 1.0 Europa radii. In contrast to typical Io FPT crossings, the instrument background caused by penetrating energetic radiation (> ~5–10 MeV electrons) increased during the Europa FPT crossing. ©2020. American Geophysical Union. All Rights Reserved. |
| 作者单位 | Southwest Research Institute, San Antonio, TX, United States; Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, United States; Johns Hopkins University Applied Physics Lab, Laurel, MD, United States; Department of Astrophysical Sciences, Princeton University, Princeton, NJ, United States; Department of Physics and Astronomy, University of Iowa, Iowa City, IA, United States; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO, United States; Space Research Corporation, Annapolis, MD, United States; Goddard Space Flight Center, Greenbelt, MD, United States; Department of Electrical Engineering and Information Science, National Institute of Technology (KOSEN), Niihama College, Niihama, Japan; Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France; Institute of Geophysics and Meteorology, University of Cologne, Cologne, Germany
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| APA |
Allegrini F..,Gladstone G.R..,Hue V..,Clark G..,Szalay J.R..,...&Wilson R.J..(2020).First Report of Electron Measurements During a Europa Footprint Tail Crossing by Juno.Geophysical Research Letters,47(18).
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