Search Publications
Langmuir Wave Activity: Comparing the Ulysses Solar Minimum and Solar Maximum Orbits
McComas, D. J.; Lin, Naiguo; MacDowall, R. J.
We examine the occurrence and intensity of Langmuir wave activity (electrostatic waves at the electron plasma frequency) during the solar minimum and solar maximum orbits of Ulysses. At high latitudes during the solar minimum orbit, occurrences of Langmuir waves in magnetic holes were frequent; in the second orbit, they were less common. This diff…
In situ Wave Phenomena Associated with Magnetic Clouds and Other Ejecta
MacDowall, R. J.; Thejappa, G.
We present Ulysses Unified Radio and Plasma Wave (URAP) observations of ion-acoustic waves associated with magnetic clouds and ejecta. The peak intensities of these waves, which usually occur inside CMEs when T e/ T i≫1, are not correlated with heliocentric distance or electron to ion temperature ratio inside the CMEs.
Decay of Magnetic Field Irregularities Observed by Ulysses
Balogh, André; Erdos, Géza; Kóta, József
We study the solar cycle, radial, and latitudinal dependence of the characteristics of magnetic field irregularities in the Heliosphere. The frequency of magnetic field discontinuities is determined, using high time resolution magnetic field observations by Ulysses, covering the time interval from 1992 to 2000. The quasi-linear scattering mean fre…
Modulation Near Solar Maximum at High Solar Latitudes: Observations From the Ulysses Cospin High Energy Telescope
McKibben, R. B.; Zhang, M.; Lopate, C.
The three-dimensional structure of the solar maximum modulation of cosmic rays in the heliosphere can be studied for the first time by comparing observations from Ulysses at high solar latitudes to those from in-ecliptic spacecraft, such as IMP-8. Observations through mid-2000 show that changes in modulation remain well correlated at Earth and Uly…
Cosmic Ray Isotopic Composition Studies with the Ulysses High Energy Telescope: Implications for Origin and Distribution in the Galaxy
Simpson, J. A.; Connell, J. J.
The isotopic abundances of the Galactic cosmic radiation measured in the Heliosphere provide unique information on acceleration, propagation modes and containment times in the Galactic magnetic fields. Nuclear interactions with interstellar matter lead to observable γ-radiation production and, thus, to direct information on cosmic ray distribution…
Low Energy Particles in the Global Heliosphere 2001 2004: 1 to 90 AU
Krimigis, S. M.; Lanzerotti, L. J.; Armstrong, T. P. +4 more
Charged particle instrumentation that will be flying on six spacecraft in the heliosphere between 1 and 90 AU during 2001 2004 will provide a global view of the interplanetary medium that has not heretofore been available. Comparative analyses of the data that will be obtained will provide new understanding of the global evolution of heliospheric …
Three-Dimensional Solar Wind Modeling Using Remote-Sensing Data
Jackson, B. V.; Hick, P. P.
We have developed a computer-assisted tomography (CAT) technique that iteratively modifies a kinematic solar wind model to least-squares fit heliospheric remote sensing observations (interplanetary scintillation and Thomson-scattering observations). These remote sensing data cover a large range of solar elongations, and access high-latitude region…
Solar Wind Composition at Solar Maximum
Bochsler, Peter
Although coronal mass ejections have traditionally been thought to contribute only a minor fraction to the total solar particle flux, and although such events mainly occur in lower heliographic latitudes, the impressive spectacle of eruptions - observed with SOHO/LASCO even at times of solar minimum - indicates that an important part of the low-la…
UVCS Observations of Velocity Shear at Streamer Boundaries in the Corona
Habbal, Shadia Rifai; Woo, Richard; Vial, Jean-Claude
Measurements of the intensities of the Ovi 1032 and 1037 Å spectral lines in the southern solar hemisphere, from 1.5 to 5 R_s, were made with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS) in May 2000 close to solar maximum. The ratio of the intensity of the two oxygen lines is used as a proxy for solar wind velocity in the inner corona. Whi…
Rigidity Dependence and Time Response of Cosmic Rays to the Modulation Steps in the Rising Part of Solar Cycle 23. Cospin/ket Results
Kunow, H.; Heber, B.; Müller-Mellin, R. +4 more
Previous work on the latitudinal gradient and on the amplitude of the recurrent cosmic ray decreases, has shown that their magnitude does not decrease monotonically with the particle rigidity, but it presents a broad maximun around 1 2 GV. We have extended this analysis to study the behaviour of cosmic-ray particles during the modulation steps in …