Search Publications
Electron temperature anisotropy constraints in the solar wind
Maksimovic, Milan; Marsch, Eckart; Scime, Earl E. +3 more
We have performed a statistical study of a substantial amount of electron data acquired in the solar wind to understand the constraints on electron temperature anisotropy by plasma instabilities and Coulomb collisions. We use a large data set of electron measurements from three different spacecraft (Helios I, Cluster II, and Ulysses) collected in …
Turbulence transport throughout the heliosphere
Matthaeus, W. H.; Bieber, J. W.; Smith, C. W. +4 more
We employ a turbulence transport model to compute distributions of turbulence throughout the heliosphere. The model determines the radial dependence of three (coupled) quantities that characterize interplanetary turbulence, the energy per unit mass, the cross helicity or Alfvénicity, and a similarity length scale. A fourth integrated quantity, the…
An update to a Saturnian longitude system based on kilometric radio emissions
Gurnett, D. A.; Kurth, W. S.; Averkamp, T. F. +2 more
The period of Saturn kilometric radiation modulation as determined by Voyager forms the basis for a longitude system (SLS) recognized by the International Astronomical Union. However, Ulysses and Cassini observations have shown that this modulation period varies by the order of one percent on timescales of a few years and, hence, does not represen…
Statistical validation of a solar wind propagation model from 1 to 10 AU
Hansen, Kenneth C.; Zieger, Bertalan
A one-dimensional (1-D) numerical magnetohydrodynamic (MHD) code is applied to propagate the solar wind from 1 AU through 10 AU, i.e., beyond the heliocentric distance of Saturn's orbit, in a non-rotating frame of reference. The time-varying boundary conditions at 1 AU are obtained from hourly solar wind data observed near the Earth. Although simi…
Measuring suprathermal electron parameters in space plasmas: Implementation of the quasi-thermal noise spectroscopy with kappa distributions using in situ Ulysses/URAP radio measurements in the solar wind
Zouganelis, I.
We discuss the implementation of the quasi-thermal noise spectroscopy using kappa velocity distribution functions for the electrons. The quasi-thermal noise spectroscopy is a powerful tool for in situ space plasma diagnostics based on the analysis of the electrostatic field spectrum produced by the quasi-thermal fluctuations of electrons. The elec…
Superdiffusive transport of electrons accelerated at corotating interaction regions
Zimbardo, Gaetano; Perri, Silvia
Energetic particles in the solar wind are accelerated at interplanetary shock waves associated with corotating interaction regions (CIRs) and propagate in the presence of a spectrum of magnetic turbulence, which causes pitch angle scattering upstream of the shock. Besides normal diffusive transport, we study the possibility of superdiffusive trans…
Suprathermal electron evolution in a Parker spiral magnetic field
Owens, M. J.; Crooker, N. U.; Schwadron, N. A.
Suprathermal electrons (>70 eV) form a small fraction of the total solar wind electron density but serve as valuable tracers of heliospheric magnetic field topology. Their usefulness as tracers of magnetic loops with both feet rooted on the Sun, however, most likely fades as the loops expand beyond some distance owing to scattering. As a first …
Combining remote and in situ observations of coronal mass ejections to better constrain magnetic cloud reconstruction
Owens, M. J.
Determination of the nonradial extent of magnetic clouds (MCs) is vital for two key reasons. First, it affects the amount of "drag" a fast MC experiences and therefore controls the travel time from the Sun to 1-AU, a critical parameter for space-weather prediction. Second, it is vital to estimating the flux content of MCs, which in turn is importa…
Influence of large-scale interplanetary structures on energetic particle propagation: September 2004 event at Ulysses and ACE
Lario, D.; Lanzerotti, L. J.; Decker, R. B. +1 more
An intense solar energetic particle (SEP) event was detected in September 2004 by near-Earth spacecraft and by Ulysses at 5.4 AU. Characteristics of the intensity and anisotropy time profiles at both heliospheric locations were determined by the presence of a corotating low-density, low-speed, and low-proton-beta βp solar wind stream. T…
First analyses of planar magnetic structures associated with the Halloween 2003 events from the Earth to Voyager 1 at 93 AU
Intriligator, Devrie S.; Horbury, Timothy S.; Rees, Adam
We perform the first analyses of planar magnetic structures beyond 5 AU. We also perform the first analyses of planar magnetic structures associated with the Halloween 2003 solar events. Our analyses show that planar magnetic structures (PMS) are associated with the interplanetary manifestation of the Halloween 2003 solar events over a wide range …