ON THE STRUCTURE OF CORONAL RAYS

The ray structures of the corona are assumed to consist of folds and p lies of magnetic surfaces with a large gradient of electron density wh en projected on the plane of the sky. We show that the number of cross ings of coronal rays with an arbitrary closed contour is even. This re sult allows us to classify the peculiar points of observed structures. We apply our method to coronal observations performed between 1936 an d 1984.