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Heliocentric radius of the cosmic ray modulation boundary
Author(s) -
Randall B. A.,
Van Allen J. A.
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i007p00628
Subject(s) - cosmic ray , radius , physics , modulation (music) , sunspot , astrophysics , sunspot number , range (aeronautics) , solar physics , solar radius , solar minimum , solar maximum , astronomy , meteorology , computational physics , solar wind , solar cycle , coronal mass ejection , nuclear physics , plasma , magnetic field , computer security , computer science , acoustics , materials science , quantum mechanics , composite material
We have made a semi‐empirical analysis of our extensive body of observed cosmic ray intensity data from Pioneers 10 and 11 and related spectral information from other authors in order to infer the radius R of the modulation region surrounding the sun. During the period 1972‐1985 the inferred values of R vary with time systematically and in a manner generally similar to that of sunspot numbers. The range of values of R is from 42 AU at the time of minimum solar activity (∼ 1976) to 88 AU about 1.5 yr following the time of maximum solar activity (∼ 1980). A specific, testable prediction is that Pioneer 10 will reach the modulation boundary in 1988 and will remain in its vicinity for several years thereafter.