Average Elemental and Isotopic Composition of Small Solar Energetic Particle Events
Using the Solar Isotope Spectrometer on the Advanced Composition Explorer, we have measured the heavy (Z≥6) element abundances of 33 small solar energetic particle (SEP) events which occurred between 4 April, 1998 and 3 December, 2000. The events have been classified according to their elemental and isotopic composition as well as other defining characteristics. With the event-averaged heavy element fluxes, we have investigated the dependence of elemental abundances relative to those of the solar photosphere on first ionization potential (FIP). Where possible, we have examined the FIP fractionation effects on the average composition of the small SEP events, and discuss the ensuing implications for the origin and acceleration of nuclei in these events.
Additional Information© Copernicus Gesellschaft 2001. This research was supported by NASA at Caltech (under grant NAG5-6912), JPL, and GSFC. We thank the EPAM science team for providing the proton fluxes used to define the time periods of low solar activity in this paper.
Published - 2001-45.pdf