Search Publications
Weaker solar wind from the polar coronal holes and the whole Sun
McComas, D. J.; Goldstein, B. E.; Schwadron, N. A. +4 more
Observations of solar wind from both large polar coronal holes (PCHs) during Ulysses' third orbit showed that the fast solar wind was slightly slower, significantly less dense, cooler, and had less mass and momentum flux than during the previous solar minimum (first) orbit. In addition, while much more variable, measurements in the slower, in-ecli…
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…
Decrease in heliospheric magnetic flux in this solar minimum: Recent Ulysses magnetic field observations
Smith, Edward J.; Balogh, Andre
The Ulysses spacecraft has traveled from the solar equator at 1.3 and 5.3 AU to above the polar caps at 2.2 AU three times during the last 17 years and has provided measurements of the solar-heliospheric magnetic field. The open magnetic flux, i.e., the radial component, BR, multiplied by the square of the radial distance, r, is indepen…
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…
A Comprehensive View of the 2006 December 13 CME: From the Sun to Interplanetary Space
Liu, Y.; Sauvaud, J. -A.; Luhmann, J. G. +7 more
The biggest halo coronal mass ejection (CME) since the Halloween storm in 2003, which occurred on 2006 December 13, is studied in terms of its solar source and heliospheric consequences. The CME was accompanied by an X3.4 flare, EUV dimmings, and coronal waves. It generated significant space weather effects such as an interplanetary shock, radio b…
Density of neutral interstellar hydrogen at the termination shock from Ulysses pickup ion observations
Möbius, E.; Bzowski, M.; Gloeckler, G. +2 more
Aims: By reevaluating a 13-month stretch of Ulysses SWICS H pickup ion measurements near 5 AU close to the ecliptic right after the previous solar minimum, this paper presents a determination of the neutral interstellar H density at the solar wind termination shock and implications for the density and ionization degree of hydrogen in the local int…
Identifying Current-Sheet-like Structures in the Solar Wind
Li, G.
In past years, measurements of the solar wind plasma have advanced our understanding of MHD turbulence tremendously. At small scales, the solar wind is believed to be ve`xry multifractal with nonlinear interactions causing an intermittent energy dissipation, leading to possible current-sheet structures. In this Letter, we propose a systematic data…