Search Publications
Magnetohydrodynamic modeling of the solar corona during Whole Sun Month
Thompson, B. J.; Forsyth, R. J.; Biesecker, D. A. +7 more
The Whole Sun Month campaign (August 10 to September 8, 1996) brought together a wide range of space-based and ground-based observations of the Sun and the interplanetary medium during solar minimum. The wealth of data collected provides a unique opportunity for testing coronal models. We develop a three-dimensional magnetohydrodynamic (MHD) model…
Acceleration of the fast solar wind by the emergence of new magnetic flux
Schwadron, N. A.; Zurbuchen, T. H.; Fisk, L. A.
Recent observations have shown that small magnetic loops are continuously emerging within supergranules in the solar photosphere. The subsequent reconnection of this emerging flux with field lines which open into the corona should define the Poynting's vector and mass flux into the corona. These two quantities uniquely determine the final energy f…
Three-dimensional propagation of coronal mass ejections in a structured solar wind flow 2. CME launched adjacent to the streamer belt
Pizzo, V. J.; Odstrčil, D.
A three-dimensional (3-D) numerical hydrodynamic model is used to investigate the evolution of coronal mass ejections (CMEs) launched at several heliographic positions into a tilted-dipole ambient solar wind (SW) flow, which is appropriate around solar activity minimum and declining phase. The CME is injected as an overpressured plasma cloud. Resu…
Filtration of interstellar hydrogen in the two-shock heliospheric interface: Inferences on the local interstellar cloud electron density
Gloeckler, George; Geiss, Johannes; Lallement, Rosine +3 more
The solar system is moving through the partially ionized local interstellar cloud (LIC). The ionized matter of the LIC interacts with the expanding solar wind forming the heliospheric interface. The neutral component (interstellar atoms) penetrates through the heliospheric interface into the heliosphere, where it is measured directly ``in situ'' a…
Quasi-thermal noise in a drifting plasma: Theory and application to solar wind diagnostic on Ulysses
McComas, D. J.; Moncuquet, Michel; Issautier, Karine +2 more
The present paper provides the basic principles and analytic expressions of the quasi-thermal noise spectroscopy extended to measure the plasma bulk speed, as a tool for in situ space plasma diagnostics. This method is based on the analysis of the electrostatic field spectrum produced by the quasi-thermal fluctuations of the electrons and by the D…
A two-fluid, MHD coronal model
Wu, S. T.; McComas, D. J.; Poletto, G. +2 more
We describe first results from a numerical two-fluid MHD model of the global structure of the solar corona. The model is two-fluid in the sense that it accounts for the collisional energy exchange between protons and electrons. As in our single-fluid model, volumetric heat and momentum sources are required to produce high speed wind from coronal h…
Energy spectra of 50-keV to 20-MeV protons accelerated at corotating interaction regions at Ulysses
Simnett, G. M.; Lario, D.; Balogh, A. +6 more
We analyze here the energy spectra of 50-keV to 20-MeV protons accelerated at corotating shocks observed at Ulysses in the southern heliosphere during 1992 and 1993. In general, our results are inconsistent with the predictions of two models based on diffusive shock acceleration theory (Fisk and Lee [1980] and Jones and Ellison [1991]). The main r…
Solar wind electrons: Parametric constraints
Goldstein, Bruce E.; Gary, S. Peter; Skoug, Ruth M. +1 more
Solar wind electrons are often observed to consist of two distinguishable components, a thermal, more dense core and a suprathermal, less dense halo. In this core/halo model linear Vlasov theory for the whistler heat flux instability predicts dimensionless heat flux thresholds which decrease as the electron core beta, β~∥c, increases. I…
Identification of trailing edge solar wind stream interfaces: A comparison of Ulysses plasma and composition measurements
Crooker, N. U.; Burton, M. E.; Smith, E. J. +2 more
Measurements of the specific entropy argument of the solar wind protons, T/nγ-1, reveal that nearly every occurrence of a high-speed stream seen at Ulysses in 1992-1993 is characterized by an abrupt interface at its trailing edge. These observations, made by the solar wind plasma instrument (SWOOPS), at a heliocentric range of 4.5 to 5 …
Amplitude evolution and rigidity dependence of the 26-day recurrent cosmic ray decreases: COSPIN/KET results
Kunow, H.; Bothmer, V.; Potgieter, M. S. +8 more
In the time interval extending from July 1992 to July 1994, Ulysses climbed from 10°S heliographic latitude up to over 70°S. During this time lapse, solar minimum conditions were gradually approached, which, in turn, led to stable and long-lasting corotating interaction regions (CIRs). The corotating particle events observed during this period, as…