Composition and energy spectra of ions accelerated in Corotating Interaction Regions Available to Purchase

Corotating Interaction Regions (CIRs) arise from the interaction of fast- and slow-solar wind streams. Ions accelerated in association with CIRs are one of the primary heliospheric energetic particle populations, often reaching energies of >10 MeV/nucleon and intensities near 1 MeV/nucleon comparable to large solar energetic particle events. New instruments on the WIND, Ulysses, and ACE spacecraft have for the first time probed the CIR population in the suprathermal energy range. These new observations show that the 1 AU CIR abundances of suprathermal particles are locally accelerated, most often without any corresponding shock. In addition, enormous abundance enhancements of $He+$ (rare in the solar wind) and details of heavy ion spectra and abundance ratios show that the source population for the energetic particles is not the solar wind itself but is most likely the suprathermal ion population in the speed range ∼1.8–2.5 times that of the solar wind.