Variability of the quiet photospheric network

Abstract

High resolution photographs of the photospheric network taken in the CaIIK 3933 Â line and λ 4308 A are analysed in order to study the variation, in latitude and over the solar cycle, of its density (the density is defined as the number of network elements - also called facular points - per surface unity). It appears that the density of the photospheric network is not distributed uniformly at the surface of the Sun : on september 83 it was weakened at both the low (equatorial) and high (polar) active latitudes, while it was tremendously enhanced toward the pole. The density at the equator is varying in antiphase to the sunspot number : it increases by a factor 3 or more from maximum to minimum of activity. Implications for the latitude and cyclic variation of the magnetic flux in the quiet Sun are discussed.