Solar modulation of galactic cosmic rays in the outer heliosphere

Journal Article · Thu Oct 15 04:00:00 EDT 1981 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/183661· OSTI ID:5884727

McDonald, F B; Lal, N; Trainor, J H; Van, M A.I. Hollebeke; Webber, W R

The observations of Pioneer 10 and Helios 1 and 2 of the intensity changes of galactic cosmic rays associated with the enhanced solar activity during the onset of cycle 21 over an extended range of energy and heliocentric distance provide new insight on the relative importance of the various processes involved in the long-term modulation. There is a close correspondance between changes at 1 AU and those at 23 AU for hydrogen and helium in the range of 100--200 MeV per nucleon. The relative decrease is of the same order at both locations with an appropriate time delay that corresponds to an outward propagation velocity of some 550 km s/sup -1/. These measurements suggest that the recently discovered, moderately long-lived, radially propagating shock waves in the outer heliosphere may play a key role in the long-term modulation. At the location of Pioneer 10, the variations in the intensity of the anomalous and galactic cosmic-ray helium are well correlated.

• Research Organization: Laboratory for High Energy Aastrophysics, NASA/Goddard Space Flight Center, Greenbelt, Maryland
• OSTI ID: 5884727
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 249:2; 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 PROTONS
COSMIC RADIATION
COSMIC RAY PROPAGATION
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
FLUIDS
GASES
HADRONS
HELIUM
HYDROGEN
INTERPLANETARY SPACE
IONIZING RADIATIONS
NONMETALS
NUCLEONS
PROTONS
RADIATIONS
RARE GASES
SHOCK WAVES
SOLAR ACTIVITY
SPACE