Interplanetary propagation of flare-associated energetic particles

Journal Article · Thu Jun 15 04:00:00 EDT 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156225· OSTI ID:6684249

Ma Sung, L S

A propagation model which combines a Gaussian profile for particle release from the Sun, with interplanetary particle densities predicted by focused diffusion, is proposed to explain the propagation history of flare-associated energetic particles. This model, which depends on only two parameters, successully describes the time-intensity profiles of 30 proton and electron events originating from the western hemisphere of the Sun. When the predicted and observed density profiles are compared, it is found that the scattering mean free path lambdais on the order of 0.1 to 0.3 AU for 4-80 MeV protons and is a factor of 2 to 3 smaller for 0.5-1.1 MeV and 3-12 MeV electrons. Since the rigidities here differ by more than two orders of magnitude, this implies that lambda is only weakly dependent on rigidity. The rigidity dependence of lambda, as well as its magnitude, strongly disagrees with that predicted by the quasi-linear theory of pitch-angle scattering. Generally, particles are released from the Sun over a finite interval. Approximating this profile of injection by a truncated Gaussian, we find that the rms width sigma is less than 1 hour for most events. The injection width sigma decreases with velocity, but it does not depend on rigidity. In almost all events, particle release begins at the time of flare acceleration.

• Research Organization: Department of Physics and Astronomy, University of Maryland, College Park
• OSTI ID: 6684249
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 222:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
COSMIC RADIATION
DIFFUSION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
FLUID MECHANICS
HADRONS
HYDRODYNAMICS
INTERPLANETARY SPACE
IONIZING RADIATIONS
LEPTONS
MAGNETOHYDRODYNAMICS
MEAN FREE PATH
MECHANICS
NUCLEONS
PROTONS
RADIATIONS
SOLAR ACTIVITY
SOLAR ELECTRONS
SOLAR FLARES
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SPACE
STELLAR RADIATION