Energetic protons associated with interplanetary active regions 1-5 AU from the sun
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), Vol. 83:A2
- Country of Publication:
- United States
- Language:
- English
Similar Records
Shock-associated low-energy ion enhancements observed by Voyagers 1 and 2
RADIAL DEPENDENCE OF PEAK PROTON AND IRON ION FLUXES IN SOLAR ENERGETIC PARTICLE EVENTS: APPLICATION OF THE PATH CODE
Related Subjects
GENERAL PHYSICS
INTERPLANETARY SPACE
SOLAR PROTONS
ENERGY SPECTRA
ANISOTROPY
INTERPLANETARY MAGNETIC FIELDS
MEV RANGE
PLASMA ACCELERATION
SHOCK WAVES
SOLAR WIND
ACCELERATION
BARYONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRONS
MAGNETIC FIELDS
NUCLEONS
PROTONS
RADIATIONS
SOLAR ACTIVITY
SOLAR PARTICLES
SOLAR RADIATION
SPACE
SPECTRA
STELLAR RADIATION
640107* - Astrophysics & Cosmology- Planetary Phenomena