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Coronal Composition above the Solar Equator and the North Pole as Determined from Spectra Acquired by the SUMER Instrument on SOHO
Schühle, U.; Feldman, U.; Laming, J. M. +1 more
Using spectra obtained by the SUMER instrument on the Solar and Heliospheric Observatory (SOHO) we have determined the composition of the bulk of the coronal plasma in the vicinity of the solar surface over a polar coronal hole and an equatorial region. Our measurements show that although low first ionization potential (FIP) elements are enriched …
Galactic Cosmic-Ray Confinement Time: Ulysses High Energy Telescope Measurements of the Secondary Radionuclide 10Be
Connell, J. J.
We report new measurements of the isotopic abundances of the Galactic cosmic-ray isotopes 7Be, 9Be, and radioactive 10Be. These measurements from the Ulysses High Energy Telescope (HET) combine exceptional mass resolution with superior statistics. Measurements of radioisotopes produced as secondaries during cosmic-…
The Rapid Decay of the Optical Emission from GRB 980326 and Its Possible Implications
Piro, L.; Veilleux, S.; Pian, E. +39 more
We report the discovery of the optical counterpart to GRB 980326. Its rapid optical decay can be characterized by a power law with exponent -2.10+/-0.13 and a constant underlying source at Rc=25.5+/-0.5. Its optical colors 2.1 days after the burst imply a spectral slope of -0.66+/-0.70. The γ-ray spectrum as observed with BATSE shows th…
Toward a Realistic Diffusion Tensor for Galactic Cosmic Rays
Burger, R. A.; Hattingh, M.
We present analytical expressions for the mean free path parallel to the background magnetic field, calculated from quasi-linear theory for a composite slab/two-dimensional geometry model of turbulence. Diffusion perpendicular to the field is assumed to be anisotropic and proportional to parallel diffusion. For the variation in the magnetic field …
On the Association of Gamma-Ray Bursts with Supernovae
Galama, T. J.; Hurley, K.; Kouveliotou, C. +7 more
The recent discovery of a supernova (SN 1998bw) seemingly associated with GRB 980425 adds a new twist to the decades-old debate over the origin of gamma-ray bursts. To investigate the possibility that some (or all) bursts are associated with supernovae, we performed a systematic search for temporal/angular correlations using catalogs of BATSE and …
Evidence for Strong and Weak Turbulence Processes in the Source Region of a Local Type III Radio Burst
MacDowall, R. J.; Thejappa, G.
We present the Ulysses Unified Radio and Plasma Wave Experiment (URAP) observations of a local type III radio burst and the associated plasma wave activity generated in the vicinity of the spacecraft. These observations represent the first clear evidence of (1) the occurrence of ion-acoustic waves as well as whistlers in close association with Lan…
Cosmic-Ray 26Al and Its Decay in the Galaxy
Simpson, J. A.; Connell, J. J.
Radioactive 26Al (τ1/2=8.7×105 yr) has been resolved from stable 27Al in the cosmic radiation for the first time using the high mass resolution, charged particle telescope on the Ulysses spacecraft. The average density of the interstellar medium through which the cosmic radiation propagates was determine…
Solar Wind Consequences of a Coronal Hole Density Profile: Spartan 201-03 Coronagraph and Ulysses Observations from 1.15 Rsolar to 4 AU
Guhathakurta, Madhulika; Fisher, Richard
Spartan 201 is a small shuttle-launched and -retrieved satellite, whose mission is to study the origins of the solar wind. It carries on board two instruments, the Ultraviolet Coronal Spectrometer and the White-Light Coronagraph. The third mission of the Spartan 201 (1995 September 7-10) spacecraft was to provide a solar context for the in situ pa…
The Cosmic-Ray Radioactive Nuclide 36Cl and Its Propagation in the Galaxy
Simpson, J. A.; Connell, J. J.; DuVernois, M. A.
Radioactive 36Cl has been resolved from 35Cl and 37Cl for the first time in the cosmic radiation with measurements obtained from the high-resolution High-Energy Telescope (HET) carried on the NASA-ESA Ulysses spacecraft. Within the framework of a homogeneous propagation model wherein all 36Cl is of spall…
Stereoscopic Observations of Solar Hard X-Ray Flares Made by ULYSSES and YOHKOH
Hurley, K.; Boer, M.; Niel, M. +4 more
The Solar X-Ray/Cosmic Gamma-Ray Burst Experiment aboard the interplanetary spacecraft Ulysses has provided extensive observations of solar hard X-ray flares from a variety of angles with respect to the Sun-Earth line. During the period 1991 October-1993 June, Ulysses observed 13 flares that were also observed by the X-ray instruments aboard the J…