A Study of the Motions of Solar Prominences.

Abstract

The motions of knots of four prominences were studied from Climax fIlms. Measurements were taken by means of a polar grid supetimposed on photographic prints of each frame. The four prominences include active, eruptive, sunspot, and active-eruptive types. There are no cases of sudden velocity increase, as found by Pettit. The good detail shown by the Climax fIlms points to a twofold explanation of the supposed first law of prominence motion. It is attributed to (1) approximations involved in curve-fitting and (2) overtaking or ambiguity of identification of the knots and streamers. A parabola approximates the time-distance diagrams to a high degree of accuracy. On this basis, average accelerations are determined graphically for 85 knots and listed for both radial and angular components. The trajectories follow closely those computed by Evans on the basis of an electromagnetic field. The force fields for knots traveling similar trajectories are found to be nearly constant with time as long as the form of the prominence is constant, but the forces apparently change when the form changes. A theory of an eruptive mechanism for prominences is suggested.