Search Publications
Cyclotron resonance in coronal holes: 3. A five-beam turbulence-driven model
Hollweg, Joseph V.
Following Hollweg and Johnson [1988], Isenberg [1990], and Li et al. [1999a], we postulate that the Sun launches a flux of low-frequency Alfvén waves, which dissipate via a turbulent cascade to high frequencies where the energy is absorbed by ion cyclotron resonant interactions. The plasma consists of two proton beams, which are proxies for the re…
Alpha/proton magnetosonic instability in the solar wind
Gary, S. Peter; Winske, Dan; Reisenfeld, Daniel B. +1 more
The average relative flow velocity between protons and alpha particles in collisionless plasmas can excite several distinct alpha/proton instabilities. Here linear theory and two-dimensional hybrid simulations in a homogeneous plasma model are used to study one such mode, the alpha/proton magnetosonic instability, using plasma parameters character…
Magnetic structure of overexpanding coronal mass ejections: Numerical models
Cargill, Peter J.; Schmidt, Joachim; Spicer, D. S. +1 more
Numerical simulations are presented of the evolution of overexpanding coronal mass ejections (OCMEs), which are also magnetic clouds. The OCME is assumed to arise from the evolution of a magnetic flux rope with high plasma and magnetic pressure and high plasma density near the Sun in a high-speed solar wind. It is shown that the flux rope maintain…
Magnetic field depressions in the solar wind
Fränz, M.; Horbury, T. S.; Burgess, D.
Depressions in the interplanetary magnetic field strength occur on a wide range of temporal scales, starting with magnetic holes with a duration of several seconds and extending to larger-scale structures of more than 30 min duration. Using the magnetic field measurements of the Ulysses spacecraft, we quantify the statistical significance of the o…
A numerical study of the evolution of the solar wind from Ulysses to Voyager 2
Wang, C.; Richardson, J. D.; Gosling, J. T.
Voyager 2 continues to explore the outer heliosphere as Ulysses studies the latitudinal dependence of the solar wind. During the year 1991 these spacecraft were within 2° latitude and their radial separation was larger than 30 AU. This alignment presents a good opportunity to investigate the evolution of the solar wind and, in particular, the effe…
Radial variation of solar wind electrons inside a magnetic cloud observed at 1 and 5 AU
Balogh, A.; Reisenfeld, D. B.; McComas, D. J. +5 more
The fortuitous observations of a magnetic cloud during the ACE/Ulysses radial alignment in March 1998 provide one of the first opportunities to study the same magnetic cloud at two different radial distances. In this paper, we use data from both ACE and Ulysses to examine the expansion of the cloud as well as of the adjacent noncloud solar wind. I…
Collisional consequences of big interstellar grains
Grün, Eberhard; Landgraf, Markus
Identification by the Ulysses spacecraft of interstellar grains inside the planetary system provides a new window for the study of diffuse interstellar matter. Dust particles observed by Ulysses and confirmed by Galileo are more massive (>=10-13g) than the ``classical'' interstellar grains. Even bigger grains (~10-7g) were…
Charge state distributions of iron in impulsive solar flares: Importance of stripping effects
Ruffolo, D.; Kocharov, L.; Kartavykh, Y. Y. +2 more
A model of stochastic acceleration of heavy ions by Alfvén wave turbulence has been developed. It takes into account spatial diffusion, Coulomb losses, and the possibility of charge changes for ions during stochastic acceleration. The main processes influencing the ionic charge states are the stripping by thermal electrons and protons as constitue…
Cassini and Wind stereoscopic observations of Jovian nonthermal radio emissions: Measurement of beam widths
Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S. +2 more
During two intervals in 1999, simultaneous observations of Jupiter's decametric and hectometric radio emissions were made with the Cassini radio and plasma wave instrument (RPWS) and the radio and plasma wave instrument (WAVES) on the Wind spacecraft in Earth orbit. During January the Jovian longitude difference between the two spacecraft was abou…
Compressibility of ion cyclotron and whistler waves: Can radio measurements detect high-frequency waves of solar origin in the corona?
Hollweg, Joseph V.
The ultraviolet coronagraph spectrometer on Solar and Heliospheric Observatory (SOHO) has provided several lines of evidence strongly suggesting that coronal holes and the high-speed solar wind are heated by resonant interactions with ion cyclotron waves. Related evidence has also been provided by the solar ultraviolet measurements of emitted radi…