Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 23, 1979 | public
Journal Article

Voyager 2: Energetic Ions and Electrons in the Jovian Magnetosphere


The Voyager 2 encounter has enhanced our understanding of earlier results and provided measurements beyond 160 Jupiter radii (RJ) in the magnetotail. Significant fluxes of energetic sulfur and oxygen nuclei (4 to 15 million electron volts per nucleon) of Jovian origin were observed inside 25 RJ, and the gradient in phase space density at 12 RJ indicates that the ions are diffusing inward. A substantially longer time delay versus distance was found for proton flux maxima in the active hemisphere in the magnetotail at Jovicentric longitudes λIII, = 260° to 320° than in the inactive hemisphere at λIII, = 85° to l10°. These delays can be related to the radial motion of plasma expanding into the magnetotail, and differences in the expansion speeds between the active and inactive hemispheres can produce rarefaction regions in trapped particles. It is suggested that the 10-hour modulation of interplanetary Jovian electrons may be associated with the arrival at the dawn magnetopause of a rarefaction region each planetary rotation.

Additional Information

© 1979 American Association for the Advancement of Science. Received for publication 26 September 1979. We thank N. Ness and his colleagues on the Voyager magnetometer team for providing the magnetic field data used in this analysis. We thank the Voyager Project and the enthusiastic staff of our laboratories at the California Institute of Technology (Caltech) and the Goddard Space Flight Center (GSFC) for splendid support. Special thanks go to W. Althouse and J. Povlis (Caltech), J. Broomhall and J. Zipse of Computer Sciences Corporation, W. Davis, H. Domchick, and D. Stilwell (GSFC), and E. Franzgrote (Jet Propulsion Laboratory) who had major responsibilities. The team was greatly assisted in the near-real-time data analysis by the following Caltech undergraduates: T. Cowan, J. Ennis, D. Gordon, H. King, and especially T. Van Eck who wrote several special computer programs. Supported by NASA under contracts NAS 7-100 and NGR 05-002-160.

Additional details

August 19, 2023
October 23, 2023