*Astron. Astrophys. 344, 709-717 (1999)*
## On features of Faraday rotation of the decametric radio emission in the Jovian magnetosphere
**
V.E. Shaposhnikov**^{ 1},
M.Y. Boudjada^{ 2},
H.O. Rucker^{ 2},
V.V. Zaitsev^{ 1} and
M. Aubier^{ 3}
^{1} Institute of Applied Physics, Russian Academy of Sciences, Uljanov St. 46, 603600 Nizhny Novgorod, Russia
^{2} Space Research Institute, Austrian Academy of Sciences, Halbaerthgasse 1, A-8010 Graz, Austria
^{3} Observatoire de Meudon, F-92195 Meudon, France
*Received 8 June 1998 / Accepted 5 January 1999*
**Abstract**
Jovian decametric emission exhibits a high degree of linear
polarization. During its propagation the radiation crosses the Jovian
magnetosphere and the terrestrial ionosphere which involves Faraday
rotation of the polarization ellipse. We develop the basic equation
necessary to estimate the amount of Faraday rotation of the
polarization ellipse of the Jovian decametric emission in the
different plasmas crossed by the emission, assuming that the different
emission frequencies *f* are emitted from different regions. This
assumption modifies the equation adding a new term
, the coefficient *C* which
depends on the Jovian magnetospheric plasma inhomogeneity across the
emission ray paths. This term being taken into consideration gives the
possibility to investigate the Jovian magnetospheric plasma
inhomogeneity across the emission ray paths due to the Faraday
rotation measurements. Using spectropolarimeter observations performed
at the Nançay Observatory (France) we derive the wave ellipse
orientation allowing to get the total amount of Faraday rotation
between the source and the observer.
We find that the amount of rotation could as well be described by two
approximate formulae: the quadratic (
is a function of and
) and the parabolic
( is a function of
and
). This ambiguous result is due to the
limited number of the experimental data and the short frequency band
of the observations. We calculate the rotation measure along the
propagation path from the source at Jupiter to the observer and the
value of the position angle of the polarization ellipse at the
emission point and estimate the characteristic latitude scale of the
Io torus inhomogeneity. We find that within the same data set the use
of different approximate formulae leads to different estimations of
the rotation measure and position angle. Besides, we show that an
incorrect choice of the frame interval of the polarization ellipse
angle can lead to an essential error on the estimation of this
angle.
**Key words:** polarization
planets and satellites: individual:
Jupiter
radio continuum: solar system
*Send offprint requests to:* V.E. Shaposhnikov
This article contains no SIMBAD objects.
### Contents
© European Southern Observatory (ESO) 1999
Online publication: March 18, 1999
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