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Solar Wind Stream Interactions and the Wind Speed-Expansion Factor Relationship.
Goldstein, B. E.; Phillips, J. L.; Sheeley, N. R., Jr. +1 more
Previous studies have shown that the solar wind speed observed near Earth is inversely correlated with the divergence rate of magnetic flux tubes near the Sun. We test the global validity of this relationship by employing Ulysses wind speed measurements during 1990-1997 as well as inecliptic data for 1976-1997. When the correspondence between wind…
Acceleration of Solar Wind Ions by Nearby Interplanetary Shocks: Comparison of Monte Carlo Simulations with Ulysses Observations
Baring, Matthew G.; Forsyth, Robert J.; W. Ogilvie +1 more
Various theoretical techniques have been devised to determine distribution functions of particles accelerated by the first-order Fermi mechanism at collisionless astrophysical shocks. The most stringent test of these models as descriptors of the phenomenon of diffusive acceleration is a comparison of the theoretical predictions with observational …
A Linear Relationship between the Latitude Gradient and 26 Day Recurrent Variation in the Fluxes of Galactic Cosmic Rays and Anomalous Nuclear Components. I. Observations
Zhang, Ming
We find that there exists a linear relationship between the magnitude of latitude gradient and the amplitude of 26 day recurrent variations in the fluxes of galactic cosmic rays and anomalous nuclear components. This result is based on energetic charged particle measurements from the University of Chicago High Energy Telescope (HET) in the Cosmic …
Diffusive Shock Acceleration in Oblique Magnetohydrodynamic Shocks: Comparison with Monte Carlo Methods and Observations
Jones, T. W.; Kang, Hyesung
We report simulations of diffusive particle acceleration in oblique magnetohydrodynamical (MHD) shocks. These calculations are based on extension to oblique shocks of a numerical model for ``thermal leakage'' injection of particles at low energy into the cosmic-ray population. That technique, incorporated into a fully dynamical diffusion-convectio…
Isotopic Abundances of Fe and Ni in Galactic Cosmic-Ray Sources
Simpson, J. A.; Connell, J. J.
With a new instrument, designed to determine the isotopic composition of Galactic cosmic-ray nuclei, on board the Ulysses spacecraft, we report relative abundance measurements for 54Fe, 55Fe, 56Fe, 57Fe, 58Fe and 58Ni, 59Ni, 60Ni, 62Ni in the overall…
The Giant 1991 June 1 Flare: Evidence for Gamma-Ray Production in the Corona and Accelerated Heavy Ion Abundance Enhancements from Gamma-Ray Spectroscopy
Ramaty, Reuven; Mandzhavidze, Natalie; Barat, Claude +1 more
We investigated the implications of the gamma-ray line emission observed with Granat/PHEBUS from the behind-the-limb flare on 1991 June 1. We showed that thin target interactions are required to account for the very high observed ratio of the nuclear line emission in the 1.1-1.8 MeV and 4.1-7.6 MeV energy bands, which are populated predominantly b…
Galactic Cosmic-Ray Manganese: Ulysses High Energy Telescope Results
DuVernois, M. A.
The Ulysses High Energy Telescope (HET) allows for a study of Galactic cosmic-ray manganese because of the telescope's excellent mass resolution and large collecting area. The manganese isotopes in the cosmic rays provide a means of studying the parameters of the cosmic-ray propagation in the Galaxy. Each of the isotopes probes a separate aspect o…
Third Interplanetary Network Localization, Time History, Fluence, Peak Flux, and Distance Lower Limit of the 1997 February 28 Gamma-Ray Burst
Frontera, F.; Orlandini, M.; Cline, T. +9 more
The gamma-ray burst of 1997 February 28 was localized using the arrival time analysis method with the Ulysses, BeppoSAX, and WIND spacecraft. The result is a +/-31.5" (3 σ) wide annulus of possible arrival directions that intersects both the position of the burst determined independently by the BeppoSAX Wide Field Camera and the position of a fadi…
The Hardness-Intensity Correlation in Bright Gamma-Ray Bursts
Hurley, K.; Sunyaev, R.; Boer, M. +10 more
The presence of a hardness-intensity correlation (HIC) is demonstrated in a sample of 77 bright bursts observed by the Phebus and Ulysses gamma-ray burst (GRB) experiments. Using simulations, we find a significant correlation (5 σ) between the peak spectral hardness and the peak intensity in Phebus. Moreover, the HIC is compatible with a single re…
An Investigation into Sulfur Isotopes in the Galactic Cosmic Rays
Thayer, M. R.
Measurements made by the Ulysses High Energy Telescope (HET) have made it possible for the first time to resolve the individual isotopes of sulfur 32S, 33S, and 34S. The measured ratio of Galactic cosmic-ray 34S/32S in the heliosphere is 24.2% +/- 2.7%. Based on this value, the Galactic source…