Non-thermal particles in the interplanetary medium
Abstract
During the past few years we have found that the MeV ion populations from a variety different of solar and interplanetary sources have quite distinct abundances and spectra. Particles from impulsive flares are electron rich, have 3He/4He enhancements of up to 104, and enhancements in heavy elements like Fe/C by factors of 10, relative to coronal abundances. The high ionization state of Fe, +20, indicates heating of the material to temperatures up to ~20 MK (1 MK = 106 K). The enhancements are probably produced by selective absorption of plasma waves in these events. In contrast, particles from gradual solar events have strong proton enhancements at high energies, but element abundances and ionization states are more typical of ambient coronal material. The abundances, time profiles, and extended longitude distribution of gradual events indicate that particles are accelerated from the ambient corona and solar wind by a shock wave that is driven by a coronal mass ejection.
- Publication:
-
Advances in Space Research
- Pub Date:
- September 1993
- DOI:
- 10.1016/0273-1177(93)90501-2
- Bibcode:
- 1993AdSpR..13i.331R