We now know of several environments in which particle acceleration has an important dynamic role in the development of coronal and chromospheric structures and around solar-system objects.
The existence of “ solar cosmic rays” and their association with solar flares established the idea that violent particle acceleration somehow could happen on a relatively passive star ( Forbush, 1946).
MacKinnon, in The Sun as a Guide to Stellar Physics, 2019 2.2 Particle Acceleration The discussion concentrates on the GCR-related production processes and the results that can be drawn from them. (2011), which shows that a 10Be increase, that was previously suggested to be of SPE origin, did not stand out as a clear signal in an extended 10Be record. This is illustrated in a publication by Pedro et al. However, the studies are rather vague on the reliability of the solar proton signal in the data as weather and climate ‘noise’ potentially masks the small effects due to SPEs. There are some studies that discuss the possibility of detectable SPEs in ice-core 10Be records (e.g., Pedro et al., 2009 Usoskin et al., 2006). For 10Be, it has been suggested that SPEs contribute about 1–2% of the total average 10Be-production rate ( Usoskin et al., 2006). Therefore, the solar proton contribution to the radionuclide-production rates depends strongly on the energy thresholds for the production of the different radionuclides ( Lal and Peters, 1967). However, the energy of the solar particles is, on average, much lower than that of the GCRs. During such an event, the number of particles penetrating the atmosphere at the polar regions can be several orders of magnitude higher than the flux of GCRs ( Lal and Peters, 1967). Nevertheless, during solar proton events (SPEs), when the Sun emits a large amount of higher-energy particles, solar particles might produce detectable increases in radionuclide-production rates on short timescales. In general, solar cosmic rays, that is, particles ejected from the Sun, are not energy-rich enough to produce significant amounts of cosmogenic radionuclides. Muscheler, in Encyclopedia of Quaternary Science (Second Edition), 2013 Solar proton events