X-ray bright points and the solar cycle

Abstract

Soft X-ray filtergrams show the presence of large numbers of small closed regions of coronal emission. These features, called X-ray bright points, correspond to small short-lived regions of emerging magnetic flux. X-ray data for 1970 to 1978 shows that the number of X-ray bright points appears to be anticorrelated with traditional activity indices such as sunspot number. A comparison of X-ray data with KPNO magnetograms shows that to within a factor of 2 the average total amount of magnetic flux emerging over the full sun is constant through the entire period of observation. The solar cycle therefore appears to be an oscillation in the wavenumber distribution of emerging flux than of the total quantity of the magnetic flux produced.