A new cycle in the periodicity of solar flare indices.

Abstract

A new cycle of about 5.5 years has been invoked in case of the periodicity in solar flare indices. As there exists no instrumental technique for measuring directly the energy output of an optical flare, the energy emitted during flaring is estimated by the quantity known as Flare Index. The daily values of flare index have been expressed by comples Fourier series for each of the years from 1986 to 1996 which cover almost the entire 22nd solar cycle. The periodicity values for both magnetic and non-magnetic (Basal) components of flare indices have been investigated after performing power spectral analysis of the aforesaid time series. The periodicity in solar flare indices varies harmonically with time, exhibiting 5.5 years cycle of variation for both magnetic and non-magnetic(Basal) component of the said indices.