Galactic cosmic-ray radial intensity gradient and large-scale modulation in the heliosphere

Journal Article · Mon Mar 01 00:00:00 EST 1982 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/183749· OSTI ID:5497666

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

Measurements of fluxes from 1 AU on the IMP8 satellite to 11 AU on the Pioneer 11 and to >24 AU on the Pioneer 10 spacecraft show that the nucleation integral gradient is a function of the level of the approx.11 year solar modulation cycle. The gradient decreases from approx.4.5% to 1.5% throughout the solar minimum of 1975--1977, and increases to approx.2.5--3.0% per AU near maximum modulation. Pioneer 10 at >24 AU is still deep in the modulation region, leading to estimates of 50--70 AU for the radial distance to the heliopause at both solar minimum and solar maximum modulation.

• Research Organization: Enrico Fermi Institute, University of Chicago
• OSTI ID: 5497666
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Vol. 254:1
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIATION
RADIATION FLUX
INTERPLANETARY SPACE
MODULATION
SOLAR CYCLE
SOLAR WIND
IONIZING RADIATIONS
RADIATIONS
SOLAR ACTIVITY
SPACE
640101* - Astrophysics & Cosmology- Cosmic Radiation