6. Concluding remarks
The model problems we have considered for addressing the statistical characteristics of radiation formed in stochastic atmospheres provide considerable insight into the structure of prominences. In two important cases, the transparent LTE atmosphere and the opaque Non-LTE atmosphere, the theory predicts that and , so that . The fact that such a relationship is observed may be regarded as an evidence that the bright and faint regions of prominences differ with each other primarily by the mean number of constituent threads along a line-of-sight. This effect would not be observed if the contrasts were the result of variations in the optical thicknesses of individual threads. Being applied to the lines H Ly- and C ii 1336 Å, the theory leads to values of consistent with those found by the other authors. We believe that these estimates are fairly close to the actual values of , though consideration of any new source of fluctuations may alter the theoretical results presented. An example of such sources is the filling factor, which is also a random quantity capable of affecting the amplitudes of fluctuations.
The present theory may be generalized in various directions, the most important of which are consideration of the continuous analogues of the structure types as well as the non-conservative version of the Non-LTE problem and the case in which random variations of inhomogeneities are intercorrelated. This will be the subject of our future investigations.
© European Southern Observatory (ESO) 1999
Online publication: February 23, 1999