A STATISTICAL APPROACH TO THE INVESTIGATION OF FINE-STRUCTURE OF SOLAR PROMINENCES

A statistical approach is proposed for the study of the prominence fin e structure in EUV lines (T = 10(4) to 3 x 10(5) K). For different reg ions of several solar prominences, the distributions of the observed i ntensities, and their averaged characteristics (mean intensity and rel ative variance) are determined. We develop a statistical model, assumi ng that the observed intensities and their fluctuations are generated by a random number of fine-structure elements along the line-of-sight. Different models are considered, for the lines formed in the cool pla sma and in the hot transition zone. For the structural components, two geometries - slabs and threads - are assumed. We compare the statisti cal characteristics of the intensity, inferred from theoretical models , with those obtained from observations. The influence of the geometri cal model on the degree of the brightness variations is analysed. The expected number of fine-structure components along the line-of-sight i s also derived. We show that, generally, the geometry is not of major importance for the study of the spatial brightness fluctuations. A rel ative small mean number of fine-structure elements along the line-of-s ight is determined.