Evidence for regions of negligible cosmic-ray modulation in the inner heliosphere (< 10 AU)

Technical Report · Tue Jan 01 04:00:00 EST 1985

OSTI ID:6784536

Roelof, E C

Observations are reported on extended regions of heliolongitude that emitted lower-than-average solar-wind velocities at 1 AU and also exhibited higher-than-average cosmic-ray intensities as measured by the E > 35-MeV CPME anti-coincidence scintillator (28 sq cm omnidirectional geometric factor) on IMP-8. Their observations can be reproduced by a simple model, based on the observed steady solar-wind structure, wherein there is little modulation of cosmic rays in the inner heliosphere until they reach the shocked plasma beyond the stream interactions in the outer heliosphere (about 5-10 AU). Beyond the interaction boundary, the intensity exhibits a constant radial gradient (about 2%/AU). The model also offers an explanation for the irregular behavior of the rotation-averaged radial gradients observed by inside 10 AU, as well as the significant, but often ephemeral, latitude gradients observed by Voyagers 1 and 2 and IMP-8.

• Research Organization: Johns Hopkins Univ., Laurel, MD (USA). Applied Physics Lab.
• OSTI ID: 6784536
• Report Number(s): AD-A-200018/0/XAB
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics &amp; Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
GEOMETRY
INTERACTIONS
MATHEMATICS
MODULATION
PARTICLES
SOLAR ACTIVITY
SOLAR WIND
STREAMS
SURFACE WATERS