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Science. 2018 Oct 5;362(6410). pii: eaat1962. doi: 10.1126/science.aat1962.

A radiation belt of energetic protons located between Saturn and its rings.

Author information

1
Max Planck Institute for Solar System Research, 37077 Goettingen, Germany. roussos@mps.mpg.de.
2
Johns Hopkins University Applied Physics Laboratory (JHUAPL), Laurel, MD 20723, USA.
3
Max Planck Institute for Solar System Research, 37077 Goettingen, Germany.
4
Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Centre National de la Recherche Scientifique, Université Paul Sabatier, Centre National d'Etudes Spatiales, Toulouse, France.
5
Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
6
Office of Space Research and Technology, Academy of Athens, Athens 11527, Greece.
7
Department of Physics, University of Maryland, College Park, MD 20742, USA.
8
Focused Analysis and Research, Columbia, MD 11043, USA.
9
Institute of Astronomy, National Central University, 32001 Jhongli, Taiwan.
10
Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK.
11
The Centre for Planetary Sciences at University College London/Birkbeck, London WC1E 6BT, UK.
12
Southwest Research Institute, San Antonio, TX 78238, USA.
13
Laboratory for Planetary and Atmospheric Physics, Space Sciences, Technologies and Astrophysics Institute, University of Liege, Liege, Belgium.
14
National Observatory of Athens, 15236 Penteli, Greece.

Abstract

Saturn has a sufficiently strong dipole magnetic field to trap high-energy charged particles and form radiation belts, which have been observed outside its rings. Whether stable radiation belts exist near the planet and inward of the rings was previously unknown. The Cassini spacecraft's Magnetosphere Imaging Instrument obtained measurements of a radiation belt that lies just above Saturn's dense atmosphere and is decoupled from the rest of the magnetosphere by the planet's A- to C-rings. The belt extends across the D-ring and comprises protons produced through cosmic ray albedo neutron decay and multiple charge-exchange reactions. These protons are lost to atmospheric neutrals and D-ring dust. Strong proton depletions that map onto features on the D-ring indicate a highly structured and diverse dust environment near Saturn.

PMID:
30287631
DOI:
10.1126/science.aat1962

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