Solar latitude and radial dependence of the anomalous cosmic-ray helium component

Journal Article · Thu Feb 01 04:00:00 EST 1979 · Astrophys. J., Lett.; (United States)

DOI:https://doi.org/10.1086/182887· OSTI ID:6470733

McKibben, R B; Pyle, K R; Simpson, J A

We present observations of the spatial intensity gradients of 11--20 MeV per nucleon anomalous helium made with Pioneer 10 and Pioneer 11 over the radial range 1--11.3 AU for Pioneer 10 and to a heliographic latitude of 16/sup 0/ at 3.75 AU for Pioneer 11. We find evidence for a significant gradient in heliographic latitude, with flux increasing away from the equatorial plane at the rate of approx.2%--3% per degree of latitude. This result shows that the common assumption of spherical symmetry for solar modulation is incorrect. By comparison with gradients measured for 29--67 MeV per nucleon helium for 11--20 MeV and 29--67 MeV protons, we find that both the radial and latitude gradients of the low energy anomalous helium are the largest of those measured. We briefly discuss the implications of these results for the origin of the anomalous component and for solar modulation.

• Research Organization: Enrico Fermi Institute, University of Chicago
• OSTI ID: 6470733
• Journal Information: Astrophys. J., Lett.; (United States), Journal Name: Astrophys. J., Lett.; (United States) Vol. 227:3; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
COSMIC NUCLEI
COSMIC PROTONS
COSMIC RADIATION
CRYOGENIC FLUIDS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
FLUIDS
HADRONS
HELIUM
INTERPLANETARY SPACE
IONIZING RADIATIONS
NONMETALS
NUCLEI
NUCLEONS
PROTON SPECTRA
PROTONS
RADIATIONS
RARE GASES
SPACE
SPECTRA