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The 77 day periodicity in the flare rate of cycle 22
Bai, T.
AA(Stanford University, CA)
Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X), vol. 388, April 1, 1992, p. L69-L72. (ApJL Homepage)
Publication Date:
Solar Physics
NASA/STI Keywords:
Monte Carlo Method, Power Spectra, Solar Flares, Sunspots, Goes Satellites, Periodic Variations, X Ray Astronomy
Bibliographic Code:


The ocurrence times of major flares of solar cycle 22 are analyzed to detect periodicities. It is found that a periodicity of 77 d was in operation in the 15-m interval from 1988 November to 1990 February for six cycles. During the rest of 1990 no periodicity was discernible; however, it seems that the 77-d periodicity resumed in 1991. This 77-d period is interpreted as the third subharmonic of the fundamental period of about 25.5 d. In this interpretation, the 154-d periodicity is the sixth subharmonic. It is also found that when the 77-d periodicity or the 154-d periodicity is in operation the occurrence rate of major flares is much higher than is expected form the relative sunspot number.

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