Coronal abundances determined from energetic particles
Abstract
Solar energetic particles (SEPs) provide a measurement of coronal element abundances that is highly independent of the ionization states and temperature of the ions in the source plasma. The most complete measurements come from large `gradual' events where ambient coronal plasma is swept up by the expanding shock wave from a coronal mass ejection. Particles from `impulsive' flares have a pattern of acceleration-induced enhancements superimposed on the coronal abundances. Particles accelerated from high-speed solar wind streams at corotating shocks show a different abundance pattern corresponding to material from coronal holes. Large variations in He/O in coronal material are seen for both gradual and impulsive-flare events but other abundance ratios, such as Mg/Ne, are remarkably constant. SEP measurements now include hundreds of events spanning 15 years of high-quality measurement.
- Publication:
-
Advances in Space Research
- Pub Date:
- July 1995
- Bibcode:
- 1995AdSpR..15g..41R
- Keywords:
-
- Abundance;
- Particle Acceleration;
- Photosphere;
- Solar Corona;
- Solar Flares;
- Solar Wind;
- Helium;
- International Sun Earth Explorers;
- Ion Temperature;
- Ionization;
- Magnesium;
- Neon;
- Oxygen;
- Radiation Counters;
- Shock Waves;
- Stellar Mass Ejection;
- Solar Physics