[freebeard]

As a sanity check, does your 'the solar physics literature' comment on the Charlemagne Event?

phys.org: Researcher points to Sun as likely source of eighth-century 'Charlemagne event'

In addition, Melott noted that recent observations of stars similar to the Sun made by the Kepler satellite suggest that they are flaring at levels similar to that which they suggest—and higher—at average intervals of a few hundred to thousand years.