Planetary Radio Emissions VII Proceedings of the 7th International Workshop on
Planetary, Solar and Heliospheric Radio Emissions held at Graz, Austria, September 15–17, 2010
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Verlag der Österreichischen Akademie der Wissenschaften Austrian Academy of Sciences Press
A-1011 Wien, Dr. Ignaz Seipel-Platz 2
Tel. +43-1-515 81/DW 3420, Fax +43-1-515 81/DW 3400 https://verlag.oeaw.ac.at, e-mail: verlag@oeaw.ac.at |
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DATUM, UNTERSCHRIFT / DATE, SIGNATURE
BANK AUSTRIA CREDITANSTALT, WIEN (IBAN AT04 1100 0006 2280 0100, BIC BKAUATWW), DEUTSCHE BANK MÜNCHEN (IBAN DE16 7007 0024 0238 8270 00, BIC DEUTDEDBMUC)
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Planetary Radio Emissions VII Proceedings of the 7th International Workshop on
Planetary, Solar and Heliospheric Radio Emissions held at Graz, Austria, September 15–17, 2010
ISBN 978-3-7001-7125-6 Print Edition ISBN 978-3-7001-7246-8 Online Edition
Helmut Rucker
Space Research Institute, Austrian Academy of Sciences, Graz, Austria William Kurth Department of Physics and Astronomy, University of Iowa, Iowa City, USA Philippe Louarn Centre d'Etude Spatiale de Rayonnements, CNRS/Universitè Paul-Sabatier Toulouse III, Toulouse, France Georg Fischer Space Research Institute, Austrian Academy of Sciences, Graz, Austria
S.-Y. Ye,
G. Fischer,
J. D. Menietti,
Z. Wang,
D. A. Gurnett,
W. S. Kurth
S. 99 - 114 doi:10.1553/PRE7s99 Verlag der Österreichischen Akademie der Wissenschaften
Abstract: Saturn narrowband (NB) radio emissions are detected between 3 and 70 kHz, with occurrence probability and wave intensity peaking around 5 kHz and 20 kHz. The emissions usually occur periodically for several days after intensification of Saturn kilometric radiation (SKR). Originally detected by the Voyagers, the extended duration of the Cassini mission and the improved capabilities of the Radio and Plasma Wave Science (RPWS) instrument have significantly advanced our knowledge about them. For example, RPWS measurements of the magnetic component have validated the electromagnetic nature of Saturn NB emissions. Evidences show that the 20 kHz NB emissions are generated by mode conversion of electrostatic upper hybrid waves on the boundary of the plasma torus, whereas direction–finding results point to a source in the auroral zone for the 5 kHz component. Similar to SKR, the 5 kHz NB emissions have a clock–like modulation and display two distinct modulation periods identical to the northern and southern hemisphere periods of SKR. Polarization measurements confirm that most NB emissions are propagating in the L–O mode, with the exception of second harmonic NB emissions. At high latitudes closer to the planet, RPWS detected right hand polarized Z–mode NB emissions below the local electron cyclotron frequency (fce), which are believed to be the source of the L–O mode NB emissions detected above the local fce. Although the energy source for the generation of the Z–mode waves is still unclear, linear growth rate calculations indicate that the observed plasma distributions are unstable to the growth of electrostatic cyclotron harmonic emission. Alternatively, electromagnetic Z–mode might be directly generated by the cyclotron maser instability. The source Z–mode waves, upon reflection, propagate to the opposite hemisphere before escaping through mode conversion, which could explain the fact that both rotational modulation periods of NB emissions are observable in each hemisphere. Published Online: 2011/12/28 13:27:26 Object Identifier: 0xc1aa5576 0x002a1cfe Rights: .
… The 7th International Workshop on "Planetary, Solar and Heliospheric Radio Emissions" is the continuation of an established tradition: This PRE VII conference followed previous successful international workshops held at Graz, Austria, in 1984, 1987, 1991, 1996, 2001, and 2005. This 7th workshop in September 2010 offered again the unique opportunity to discuss the observations from Cassini at Saturn and to investigate the measurements by other spacecraft and from the ground of the Jovian, terrestrial and solar radio emissions, also including studies on radiation from exoplanetary sources.
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Verlag der Österreichischen Akademie der Wissenschaften Austrian Academy of Sciences Press
A-1011 Wien, Dr. Ignaz Seipel-Platz 2
Tel. +43-1-515 81/DW 3420, Fax +43-1-515 81/DW 3400 https://verlag.oeaw.ac.at, e-mail: verlag@oeaw.ac.at |