Search Publications
On the evolution of outward and inward Alfvénic fluctuations in the polar wind
Bavassano, B.; Pietropaolo, E.; Bruno, R.
Plasma and magnetic field measurements by Ulysses are used to investigate the radial evolution of hourly-scale Alfvénic fluctuations in the polar wind. The data span from 1.4 to 4.3 AU in heliocentric distance. Different radial regimes at different distances emerge. Inside about 2.5 AU the large outward traveling fluctuations decrease faster, in t…
Solar wind electron suprathermal strength and temperature gradients: Ulysses observations
Maksimovic, Milan; Gary, S. Peter; Skoug, Ruth M.
We use observations from the Ulysses electron spectrometer to examine global trends of the electron suprathermal population and to study, for the first time, the electron core, halo, and total temperature gradients in the fast solar wind over the poles. We use a data set covering the period from the beginning of the mission (1990, day of year 322)…
Modeling the motion and distribution of interstellar dust inside the heliosphere
Landgraf, M.
The interaction of dust grains originating from the local interstellar cloud with the environment inside the heliosphere is investigated. As a consequence of this interaction, the spatial distribution of interstellar dust grains changes with time. Since dust grains are charged in the interplanetary plasma and radiation environment, the interaction…
Elemental composition of the inner source pickup ions
Geiss, J.; Schwadron, N. A.; Zurbuchen, T. H. +2 more
Observations of the composition of inner source pickup ions in the solar wind, from the Solar Wind Ion Composition Spectrometer on Ulysses, are presented. The composition is similar to that of the solar wind and, in particular, contains volatile elements such as neon. These observations suggest strongly, and perhaps conclusively, that inner source…
Heliospheric modulation of cosmic ray protons: Role of enhanced perpendicular diffusion during periods of minimum solar modulation
Potgieter, Marius S.
The effect of enhanced perpendicular diffusion in the polar regions of a simulated heliosphere seems required in drift models for the modulation of galactic cosmic rays in order to find a latitude dependence of cosmic ray protons in the inner heliosphere that is compatible with Ulysses observations. This effect was studied in detail to establish h…
The solar magnetic field and the solar wind: Existence of preferred longitudes
Smith, E. J.; Neugebauer, M.; Feynman, J. +2 more
Direct measurements of the solar wind speed and the radial component of the interplanetary magnetic field acquired over more than three solar cycles are used to search for signatures of a persistent dependence of solar wind properties on solar longitude. Two methods of analysis are used. One finds the rotation period that maximizes the amplitude o…
Interstellar dust properties derived from mass density, mass distribution, and flux rates in the heliosphere
Kimura, Hiroshi; Mann, Ingrid
We apply recent in situ measurements of the mass density, mass distribution, and flux rate of dust particles that enter the solar system, i.e., the heliosphere, to study the properties and dynamics of the interstellar dust flux into the solar system. We show that depletion at the heliopause alters the flux for particles with mass, m<10-18<…
A four-fluid turbulence-driven solar wind model for preferential acceleration and heating of heavy ions
Habbal, Shadia R.; Esser, Ruth; Hu, You Qiu
We present for the first time a one-dimensional, four-fluid turbulence-driven solar wind model in order to investigate the preferential acceleration and heating of heavy ions by the resonant cyclotron interaction with parallel-propagating left-hand-polarized ion cyclotron waves. The model contains four species: electrons, protons, alpha particles,…
Inner source distributions: Theoretical interpretation, implications, and evidence for inner source protons
Geiss, J.; Schwadron, N. A.; Zurbuchen, T. H. +3 more
A new and important source of pickup ions has been recently observed for the first time, the so-called inner source. We examine properties of inner source ions at high heliographic latitudes through analysis of data from the Solar Wind Ion Composition Spectrometer on the Ulysses satellite for a period extending through the year of 1994 while Ulyss…
Alfvénic turbulence in the polar wind: A statistical study on cross helicity and residual energy variations
Bavassano, B.; Pietropaolo, E.; Bruno, R.
A study of MHD turbulence properties in the polar wind has been performed with Ulysses data. The parameters under examination are the normalized cross helicity and the normalized residual energy. The correlation coefficient between velocity and magnetic field fluctuation vectors has also been computed. Both southern and northern phases of full imm…