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Published 1990 | Published
Book Section - Chapter Open

Radial and Latitudinal Gradients of Anomalous Cosmic-Ray Oxygen and Helium from 1 to ~41 AU


We have used data from the IMP 8, Voyager 1 (VI), Voyager 2 (V2), Pioneer 11 (Pll), and Pioneer 10 (PIO) spacecraft. to determine the radial and latitudinal gradients of anomalous cosmic ray oxygen in the energy range ~7 - 25 MeV/nuc and anomalous cosmic ray helium in the energy range ~20- 25 MeV/nuc for a time period near minimum solar modulation in 1987. We find that the radial gradients of both species are decreasing functions of radial distance, r, approximately r^(-1) for oxygen and r^(-0.7) for helium. The latitudinal gradient is large and negative, implying significant spherical asymmetry in the heliospheric distribution of these particles.

Additional Information

© Organizing Committee of the 21st Int. Cosmic Ray Conference. Provided by the NASA Astrophysics Data System. We thank Todd Hoeksema for providing the neutral sheet tilt data. This work was supported in part by NASA under contracts NAS-7-918 and NAG 5-727 and grant NGR-05-002-160.

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