Search Publications
Abundances of Deuterium and Helium-3 in the Protosolar Cloud
Geiss, J.; Gloeckler, G.
The mass spectrometric determinations of the isotopic composition of helium in the solar wind obtained from (1) the Apollo Solar Wind Composition (SWC) experiment, (2) the Ion Composition Instrument (ICI) on the International Sun Earth Explorer 3 (ISEE-3), and (3) the Solar Wind Composition Spectrometer (SWICS) on Ulysses are reviewed and discusse…
Interstellar and Inner Source Pickup Ions Observed with SWICS on ULYSSES
Gloeckler, George; Geiss, Johannes
Many species of pickup ions, both of interstellar origin and from an inner, distributed source have been discovered using data from the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses. Velocity distribution functions of these ions were measured for the first time over heliocentric distances between 1.35 and 5.4 AU, both at high and low …
Deuterium Abundance in the Local ISM and Possible Spatial Variations
Linsky, Jeffrey L.
Excellent HST/GHRS spectra of interstellar hydrogen and deuterium Lyman-alpha absorption toward nearby stars allow us to identify systematic errors that have plagued earlier work and to measure accurate values of the D/H ratio in local interstellar gas. Analysis of 12 sightlines through the Local Interstellar Cloud leads to a mean value of D/H = (…
Cosmic-Ray Modulation in the Heliosphere A Phenomenological Study
McDonald, Frank B.
The heliospheric cosmic-ray network-Pioneer 10/11, Voyager 1/2, Ulysses and IMP 8 have provided detailed observations of galactic and anomalous cosmic rays over a period of time that now exceeds 25 years and extends to heliocentric distances beyond 65 AU. These data, when compared over consecutive 11 year solar cycles, clearly establishes the exis…
Measurement of the Abundance of Helium-3 in the Sun and in the Local Interstellar Cloud with SWICS on ULYSSES
Gloeckler, George; Geiss, Johannes
The abundance of 3He in the present day local interstellar cloud (LIC) and in the sun has important implications for the study of galactic evolution and for estimating the production of light nuclei in the early universe. Data from the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses is used to measure the isotopic ratio of helium (3He/4…
Transient Effects and Disturbed Conditions
Wibberenz, G.; Potgieter, M. S.; Bieber, J. W. +1 more
In the present phase of the solar cycle no big transients leading to strong modulation had been observed after 1991. Apart from a few minor disturbances cosmic rays were still recovering to a new intensity maximum. It was suggested, therefore, that existing literature from previous cycles should be critically reviewed. The scene was set by the int…
FIP Effect in the Solar Upper Atmosphere: Spectroscopic Results
Feldman, U.
Recent spectroscopic measurements from instruments on the Solar and Heliospheric Observatory (SOHO) find that the coronal composition above a polar coronal hole is nearly photospheric. However, similar SOHO observations show that in coronal plasmas above quiet equatorial regions low-FIP elements are enhanced by a factor of ≈ 4. In addition, the pr…
Modeling of 3-D Corotating Cosmic-Ray Structures in the Heliosphere
Jokipii, J. R.; Kóta, J.
We present a brief review of the modeling of corotating 3-dimensional features in heliospheric cosmic rays. The model heliosphere incorporates a wavy current sheet and Corotating Interaction Regions (CIRs). We find that present models can qualitatively account for the observed extension of recurrent 26-day cosmic-ray variations to high heliospheri…
Cosmic-Ray Transport Coefficients
Giacalone, Joe
A review of cosmic-ray transport coefficients, based on historic and recent observations and theoretical insights, is presented. Particular emphasis is on the transport of cosmic rays across the magnetic field, which is of foremost importance, and is presently poorly understood and widely debated.
Anomalous Cosmic Rays
Klecker, B.; Baring, M. G.; Leske, R. A. +22 more
We review the observed properties of anomalous cosmic rays and the present status of our knowledge of the processes by which they originate. We compiled a comprehensive set of ACR energy spectral data from various spacecraft throughout the heliosphere during the passes of Ulysses over the poles of the Sun and present first results of a detailed mo…