Search Publications
Magnetic field signatures of unevolved turbulence in solar polar flows
Balogh, A.; Horbury, T. S.; Forsyth, R. J. +1 more
Between late 1993 and the middle of 1994, Ulysses stayed almost constantly within flows from the Sun's southern polar coronal hole, traveling from 44°S to 69°S heliolatitude and between 4.0 and 2.9 AU from the Sun. Magnetic field observations within this region reveal a very different medium from that at similar heliocentric distances near the ecl…
Heating of the thermal electrons in the coma of comet P/Halley
Geiss, Johannes; Altwegg, Kathrin; Balsiger, Hans +1 more
In the inner coma of a comet the total ion (or electron) density results from an equilibrium between ion production and ion destruction. The ions are mainly produced by photoionization of cometary gas, whereas the main destruction process is dissociative recombination of molecular ions with electrons. The reaction rate for the recombination depend…
Interplanetary shock waves and large-scale structures: Ulysses' observations in and out of the ecliptic plane
Balogh, A.; Forsyth, R. J.; Smith, E. J. +3 more
We present a study of 153 fast shock waves and their relation to other large-scale features in the solar wind: corotating interaction regions (CIRs), interplanetary counterparts of coronal mass ejections (ICMEs), and the magnetic sector structure, observed by Ulysses from October 1990 to the south solar polar pass in the summer of 1994. This is a …
Propagation of three-dimensional Alfvén waves in a stratified, thermally conducting solar wind
Orlando, S.; Peres, G.; Rosner, R. +1 more
We model the propagation of three-dimensional, adiabatic, linear Alfvén waves in the solar atmosphere and wind, taking into account relevant physical effects, including gravity stratification, thermal conduction, radiative losses, and heating (via a phenomenological term). Our magnetohydrodynamic solar wind model also accounts for the momentum dep…
Ulysses assessment of the Jovian planetary field
Dougherty, M. K.; Balogh, A.; Smith, E. J. +1 more
The magnetic field measurements made by the Ulysses dual fluxgate/vector helium magnetometer during the day of closest approach to Jupiter in February 1992 are reported. The data are compared to a model which describes the field in terms of an internal spherical harmonic component together with an external current sheet field. The sensitivity of t…
Octupole model of Jupiter's magnetic field from Ulysses observations
Connerney, J. E. P.; Acuña, M. H.; Ness, N. F.
A spherical harmonic model of the planetary magnetic field of Jupiter is obtained from the Ulysses encounter observations. The magnetic field in the Jovian magnetosphere is represented using a degree and order 3 spherical harmonic for the planetary (``internal'') field, and an explicit model of the magnetodisc for the field (``external'') due to d…
Solar cycle dependence of the solar wind dynamics: Pioneer, Voyager, and Ulysses from 1 to 5 AU
Smith, Edward J.; González-Esparza, J. Américo
Significant differences between Pioneer and Voyager observations were found in solar wind structure between 1 and 6 AU. These disagreements were attributed to temporal effects related to the solar cycle, but no unifying study of Pioneer-Voyager observations was performed. On the basis of maps of large-scale features we unify previous reports of Pi…
Cometary ion pressure anisotropies at comets Halley and Grigg-Skjellerup
Coates, A. J.; Neubauer, F. M.; Johnstone, A. D.
Cometary water group ions are the dominant population controlling the interaction of comets with the solar wind. The distribution function of this population has important effects on the overall structure and boundaries in the comet-solar wind interaction and on the plasma wave activity produced. In this paper we present new results on the behavio…
Spatial evolution of the magnetic field spectral exponent in the solar wind: Helios and Ulysses comparison
Tu, C. -Y.; Marsch, E.
The spatial evolution of the spectral exponent of magnetic field fluctuations in the solar wind is investigated by a comparison of spectra and length functions obtained from Helios for in-ecliptic and from Ulysses for high-latitude observations. A similar radial evolution trend is found in both data sets for the Bz component of the magn…
Modeling of Jovian hectometric radiation source locations: Ulysses observations
Menietti, J. D.; Reiner, M. J.
The Unified Radio and Plasma Wave (URAP) experiment on Ulysses has provided unique high latitude measurements of Jovian hectometric radiation (HOM) during its encounter with Jupiter in February 1992. URAP was the first radio instrument in the Jovian environment with radio direction-finding capability, which was previously used to determine the HOM…