Spetra and Abundances of Flare and CME-Shock Accelerated He and Heavy Ions

Solar energetic particles (SEPs) show a rich variety of spectra and broad distributions of relative abundances of many ionic species and their isotopes, in particular He and many heavy elements. The most extreme enrichments are observed in low fluence and more impulsive events, which also show concave spectra. In earlier papers, in collaboration with Glenn Mason, we showed how such extreme enrichments and spectra can result by stochastic acceleration in a turbulent plasma via resonant wave-particle interactions. This model can account for the relative distributions of 3He and 4He.

After a brief review of these works we will present some new results on enrichment of ions heavier than CNO and show that flare accelerated ions can be the seeds for re-acceleration in the CME shock environment in gradual events. For large events the enrichment can also be suppressed due to dominance of non-resonance processes that have a weaker dependence on charge-to-mass ratio. Re-accelerated particle escaping the upstream of the shock will have harder photospheric abundances and broken power law spectra seen for SEPs in gradual events. Particles escaping the downstream toward the Sun may be responsible for the >100 MeV photons observed by Fermi.