|
|
 |
|
|
Ann. Geophys., 20, 599-607, 2002
www.ann-geophys.net/20/599/2002/
© European Geosciences Union 2002
Jovicentric latitude effect on the HOM radio emission observed by Ulysses/URAP at 5 AU from Jupiter
C. H. Barrow1, A. Lecacheux2, and R. J. MacDowall3
1Max-Planck-Institut für Aeronomie, D-37189 Katlenburg-Lindau, Germany
2ARPEGES, Observatoire de Paris, 92195 Meudon, France
3NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
Correspondence to: C. H. Barrow
(barrow@linmpi.mpg.de)
Abstract. During 1994 and into
1996, Ulysses was at dis-tances of 5 AU or more from Jupiter and travelling
from south to north of the ecliptic plane between jovicentric latitudes -36°
to 20°. Observations by the Unified Radio and Plasma Experiment (URAP) on
board the Ulysses spacecraft during this period have been searched for jovian
hectometric (HOM) radio events. At these distances, the HOM was only received
occasionally. The signals were generally weak and much care was needed to find
and to identify the events. All of the HOM events were observed when Ulysses
was at jovicentric latitudes between -12.2° < DUly <
14.7°, relatively close to the plane of the jovicentric equator. Both senses
of polarization were observed with left-hand (LH) predominant. The events
occurred when the jovimagnetic latitude Df
was between -8.5° and 14.2° and suggest that the HOM was only detectable
within a beam some 23° wide, centred on about 3° jovimagnetic latitude. This
is roughly consistent with previous work by Alexander et al. (1979) and by
Ladreiter and Leblanc (1989, 1991), based upon observations made by Voyager and
other spacecraft when these were relatively close to Jupiter. The results are
consistent with an emission process due to the Cyclotron-Maser instability, as
suggested by a number of scientists in the past.
Key words. Magnetospheric physics
(planetary magnetospheres) – Radio science (radio astronomy)
Full Article in PDF (418 KB) |
|
|
