Rise Times of Solar Energetic Particle Events and Speeds of CMEs
Abstract
Gradual solar energetic particle (SEP) events are assumed to be produced in coronal and interplanetary shocks driven by fast coronal mass ejections (CMEs). These fast CMEs are decelerated as they move through the slower ambient solar wind. However, the Alfven speed is decreasing with increasing distance. Faster CMEs may therefore continue to drive strong shocks for longer characteristic times than do the slower CMEs, such that shock production and injection of SEPs of a given energy will also continue longer with the faster CMEs. We test this proposition observationally by comparing the times to maxima of 20 MeV SEP events with the observed speeds of associated CMEs. The SEP/CME events are sorted by solar longitude to factor out the longitudinal dependence of the SEP rise times. A preliminary analysis comparing 20 MeV protons from the GSFC EPACT detector on the Wind satellite with CMEs observed by the LASCO coronagraph on the SOHO spacecraft showed a correlation between SEP rise times and CME speeds. We expand the database to include the 1996-2001 period for a more definitive test of the correlation. The implications of the results will be discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFMSH62A..08K
- Keywords:
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- 2111 Ejecta;
- driver gases;
- and magnetic clouds;
- 2118 Energetic particles;
- solar;
- 2139 Interplanetary shocks