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Astron. Astrophys. 363, 316-322 (2000)

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Jovian narrow-band as generator of the Jovian millisecond radio bursts

M.Y. Boudjada 1, P.H.M. Galopeau 2, H.O. Rucker 1 and A. Lecacheux 3

1 Space Research Institute, 8010 Graz, Austria
2 CETP, 78140 Velizy, France
3 UMR 8644-CNRS Observatoire de Paris-Meudon, 92180 Meudon, France

Received 18 February 2000 / Accepted 25 May 2000

Abstract

We report on the narrow-band emissions observed in the dynamic spectra of the Jovian decametric radio emissions. Such narrow-band emissions are infrequent phenomena and are related to the Jovian millisecond radio bursts (S-bursts). From the Riihimaa catalogue (Riihimaa 1991) we select narrow-band events observed in Oulu (Finland) with an acousto-optic spectrograph (AOS) with a high time resolution of about 7 ms. The AOS receiver gives the possibility to study the relationship between the S-bursts and the Jovian narrow-band emissions. For this we use the Riihimaa classification which shows sketches of millisecond radio bursts as they appear on the dynamic spectra and allows to distinguish one S-burst from another.

The analysis of the temporal evolution of the Jovian narrow-band leads to a new interpretation of the Riihimaa structures. We show that each individual structure could be decomposed in one, two or three components and related to the narrow-band. It appears that the temporal evolution of the narrow-band involves the presence of fine structures, i.e. S-bursts, with a short time duration of about few tens of milliseconds. The individual S-burst duration and the short time scale of the gap in the narrow-band account for a mechanism totally intrinsic to the radio source. Taking into consideration our new results, we show that two models, the feedback model (Calvert 1982) and filamentary model (Louarn 1997) could explain part but not the global observed features of the narrow-band. According to the previous models the drift rate of the individual S-bursts seems to associate the combined effect of the source width with the refractive index or the geometry of the source relatively to the observer.

Key words: planets and satellites: individual: Jupiter – radio continuum: solar system

Send offprint requests to: M.Y. Boudjada

Correspondence to: mohammed.boudjada@oeaw.ac.at

This article contains no SIMBAD objects.

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© European Southern Observatory (ESO) 2000

Online publication: December 5, 2000
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