Energetic protons associated with interplanetary active regions 1-5 AU from the sun

Journal Article · Wed Feb 01 04:00:00 EST 1978 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA083iA02p00553· OSTI ID:5076939

Pesses, M E; Van Allen, J A; Goertz, C K

About 100 energetic proton (0.61< or =E/sub p/< or =3.41 MeV) events have been observed at heliocentric distances between 1 and 5 AU with the University of Iowa instrument on Pioneer 11. Absolute intensities, anisotropies, and crude energy spectra are measured. The particle intensity in the events has no significant dependence on heliocentric distances. Beyond approx.2.4 AU, power spectra of the counting rates show strong peaks at about 26 and also usually 13 days corresponding to corotation of the solar wind-structure. The number of events observed per unit time interval is 10 times greater in the close vicinity of interplanetary active regions (IAR) (Smith and Wolfe, 1976) than elsewhere in interplanetary space. The frequency of occurrence of events has a marked tendency to peak with +- 5 hours of the time that IAR edges are crossed. Events observed in the vicinity of IAR have, on the average greater particle intensities, softer energy spectra, and smaller time widths at half maximum intensity than events observed elsewhere. Many of the IAR-associated events have particle anisotropies corresponding to the net flow of particles toward the sun along the interplanetary magnetic field. The phenomenological evidence strongly favors local acceleration in the planetary medium by an as yet unidentified mechanism in magnetohydrodynamic shocks. The sources of the shock-accelerated particles are apparently corotating streams of solar emitted protons, most of which have energies E/sub p/<0.61 MeV.

• Research Organization: Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242
• OSTI ID: 5076939
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 83:A2; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
ANISOTROPY
BARYONS
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY SPECTRA
FERMIONS
HADRONS
INTERPLANETARY MAGNETIC FIELDS
INTERPLANETARY SPACE
MAGNETIC FIELDS
MEV RANGE
NUCLEONS
PLASMA ACCELERATION
PROTONS
RADIATIONS
SHOCK WAVES
SOLAR ACTIVITY
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SOLAR WIND
SPACE
SPECTRA
STELLAR RADIATION