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Outer heliospheric radio emissions. II - Foreshock source modelsObservations of LF radio emissions in the range 2-3 kHz by the Voyager spacecraft during the intervals 1983-1987 and 1989 to the present while at heliocentric distances greater than 11 AU are reported. New analyses of the wave data are presented, and the characteristics of the radiation are reviewed and discussed. Two classes of events are distinguished: transient events with varying starting frequencies that drift upward in frequency and a relatively continuous component that remains near 2 kHz. Evidence for multiple transient sources and for extension of the 2-kHz component above the 2.4-kHz interference signal is presented. The transient emissions are interpreted in terms of radiation generated at multiples of the plasma frequency when solar wind density enhancements enter one or more regions of a foreshock sunward of the inner heliospheric shock. Solar wind density enhancements by factors of 4-10 are observed. Propagation effects, the number of radiation sources, and the time variability, frequency drift, and varying starting frequencies of the transient events are discussed in terms of foreshock sources.
Document ID
19920059725
Document Type
Reprint (Version printed in journal)
Authors
Cairns, Iver H. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Kurth, William S. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Gurnett, Donald A. (Iowa, University Iowa City, United States)
Date Acquired
August 15, 2013
Publication Date
May 1, 1992
Publication Information
Publication: Journal of Geophysical Research
Volume: 97
Issue: A5 M
ISSN: 0148-0227
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: JPL-959193
CONTRACT_GRANT: JPL-957723
CONTRACT_GRANT: NAGW-2040
Distribution Limits
Public
Copyright
Other