A nebula of gases from Io surrounding Jupiter |
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Authors: | Krimigis Stamatios M Mitchell Donald G Hamilton Douglas C Dandouras Jannis Armstrong Thomas P Bolton Scott J Cheng Andrew F Gloeckler George Hsieh K C Keath Edwin P Krupp Norbert Lagg Andreas Lanzerotti Louis J Livi Stefano Mauk Barry H McEntire Richard W Roelof Edmond C Wilken Berend Williams Donald J |
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Institution: | Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, Maryland 20723, USA. tom.krimigis@jhuapl.edu |
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Abstract: | Several planetary missions have reported the presence of substantial numbers of energetic ions and electrons surrounding Jupiter; relativistic electrons are observable up to several astronomical units (au) from the planet. A population of energetic (>30?]keV) neutral particles also has been reported, but the instrumentation was not able to determine the mass or charge state of the particles, which were subsequently labelled energetic neutral atoms. Although images showing the presence of the trace element sodium were obtained, the source and identity of the neutral atoms---and their overall significance relative to the loss of charged particles from Jupiter's magnetosphere---were unknown. Here we report the discovery by the Cassini spacecraft of a fast (>103?]km?]s-1) and hot magnetospheric neutral wind extending more than 0.5?]au from Jupiter, and the presence of energetic neutral atoms (both hot and cold) that have been accelerated by the electric field in the solar wind. We suggest that these atoms originate in volcanic gases from Io, undergo significant evolution through various electromagnetic interactions, escape Jupiter's magnetosphere and then populate the environment around the planet. Thus a 'nebula' is created that extends outwards over hundreds of jovian radii. |
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