Erich Otto Ernst Rieger (1 October 1935 – 14 August 2021) was a German astrophysicist who spent his research career at the Max Planck Institute for Extraterrestrial Physics (MPE) near Munich.
[4] Besides numerous confirmations of PR, its resonance harmonics were reported as well, including 5⁄6PR, 2⁄3PR, 1⁄2PR, 1⁄3PR, and 1⁄5PR, i.e., ~128, ~102, ~78, ~51, and ~31 days, called Rieger-type periodicities.
[5] Types of data periodic with Rieger cycles include solar flares, photospheric magnetic flux, group sunspot numbers, and proton speed.
[7] Most of those studies indicate a leading periodicity ranging from 152 to 158 days, which appears to be dominant particularly in the time phase from ~1979–1983, corresponding to the solar maximum activity.
[8] Various proposals exist as to the origin of the underlying resonant process behind PR in the dynamics of Sun-ejected particles and its modulations and harmonics, including possible influences of planetary constellations on the Sun.