Particle Acceleration and Sources in the November 1997 Solar Energetic Particle Events

Abstract

We repon studies of two large solar energetic panicle (SEP) events on Nov. 4 and 6. 1997 that were observed using advanced energetic panicle detectori; on the ACE and the Wind spacecraft. Both events showed enriched Fe/O, and had a ~1MeV/n ^3He/^4He ratio = 2.1x 10^(-3) , 4 times the coronal value. The Nov. 6 event had exceptionally hard spectra. with much higher intensities of high energy (10s of MeV) particles than the Nov. 4 event, yet below 1MeV per nucleon the intensities in the Nov. 6 event were lower than for Nov. 4. Strong, complex temporal variations observed for ~120 keV Fe/0 contrasted with only gradual changes of this ratio at ~25 MeV/n. A spectural break was observed in the Nov. 6 event. wherein below a few MeV/n the spectra became harder. Taken together these observations point to different seed and acceleration mechanisms dominating at low and high energies in these events.

Files

Additional details