Search Publications
The modelling of the latitude dependence of cosmic ray protons and electrons in the inner heliosphere
Potgieter, M. S.; Heber, B.; Ferrando, P. +1 more
Observations during the fast latitude scan of Ulysses show that the latitude dependence of cosmic ray protons is significantly less than predicted by drift models which were based on the Parker geometry for the heliospheric magnetic field (HMF) and diffusion coefficients ~ 1/B_p. Recent modeling with a modified HMF and enhanced turbulence in the p…
ULYSSES observations of intermittent heliospheric turbulence
Balogh, A.; Horbury, T. S.; Forsyth, R. J. +1 more
Structure function measurements of small scale magnetic field fluctuations in high speed streams emanating from the Sun's polar coronal holes are well described by a multifractal model of intermittent turbulence. We discuss structure functions and present measurements of intermittency through the transition regime - encompassing scales between wav…
MeV to GeV electron propagation and modulation: results of the KET-telescope onboard ULYSSES
Ferrando, P.
The KET instrument onboard Ulysses is continuously monitoring the flux of MeV to GeV electrons. I summarize here the main results obtained with data from the ~ 7 MeV and > 300 MeV electron KET channels, collected from launch up to the end of 1995 after completion of the Ulysses prime mission. Regarding low energy electrons, the stress is put on…
The heliospheric modulation of galactic cosmic rays at solar minimum
Potgieter, M. S.
The observations acquired by the Ulysses spacecraft since launch, but especially during the recent fast latitude scan, have provided a comprehensive, 3-dimensional view of the inner heliosphere. Together with the observations by IMP 8, Pioneer 10 and the two Voyagers, a wealth of new observations on particles and fields enables us to improve signi…
Radial and azimuthal components of the heliospheric magnetic field: ulysses observations
Forsyth, R.; Balogh, A.; Burton, M. E. +2 more
Two invariants associated with the Parker model of the solar wind involve the radial, B_R, and azimuthal, B_T, components of the heliospheric magnetic field. These invariants have been investigated using Ulysses data obtained at high latitudes in both the north and south solar hemispheres. The magnetic flux invariant, r^2B_R, is essentially indepe…
Solar modulation of galactic cosmic rays: the 3D heliosphere
Heber, Bernd; Potgieter, Marius S.; Ferrando, Philippe
The cosmic ray flux observed with the Kiel Electron Telescope onboard the Ulysses space probe varies with solar activity as well as with heliospheric position. The Ulysses' fast latitude scan performed in less than one year between September 1994 to August 1995 allowed us to obtain unique data about the latitudinal dependence of cosmic ray fluxes …
Cosmic ray latitudinal effects predicted by a three-dimensional drift model
Potgieter, M. S.; Burger, R. A.; Hattingh, M. +1 more
The Ulysses spacecraft measured surprisingly small latitudinal gradients during its first passage through the polar regions of the heliosphere. This is in contrast to predictions made with two-dimensional drift models for A > 0 magnetic polarity epochs during solar minimum modulation conditions. Several modifications to drift models have been i…
Properties of hydromagnetic waves in the polar caps: ulysses
Forsyth, R.; Balogh, A.; Tsurutani, B. T. +3 more
Properties of the large amplitude Alfvén waves which are a dominant feature of the high latitude solar wind have been studied during the pole-to-pole passage of Ulysses. In addition, an effort has begun to identify magnetosonic waves at high latitude in spite of their expected small amplitude and the presence of the large amplitude Alfvén waves. T…
Cosmic ray modulation in a non-spherical heliosphere during solar minimum conditions
Potgieter, M. S.; Haasbroek, L. J.
It is expected that the position of the modulation boundary in the equatorial and polar regions of the heliosphere depends on solar activity and possibly also on the polarity of the heliospheric magnetic field. In general, it can be assumed that the changing outward solar wind pressure causes a dynamic boundary position. Since the solar wind plasm…
Ulysses solar wind plasma observations at high latitudes
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +7 more
Ulysses reached its peak northerly heliolatitude of 80.2 degN on July 31st, 1995, and is now moving towards aphelion at 5.41 AU which it will reach in May, 1998. We summarize measurements from the solar wind plasma experiment, SWOOPS, emphasizing northern hemispheric observations but also providing southern and equatorial results for comparison. T…