Finally, we note the following. One could use similar physical assumptions (equilibrium plasma in
magnetic and gravitational fields)to model the shapes of prominences.
However, we believe this problem would be hopelessly difficult, since the field sources are situated beneath the photosphere and the field structure is rather complicated in the vicinity of the photosphere.
The situation is quite different in the corona: at solar minima, the field can be represented by a small number of spherical harmonics, as is demonstrated by a comparison of our model calculations with the structures observed.