Evolution of the helical prominence of December 15, 1992

Abstract

Following Vrsnak (1990), the observations of an eruptive prominence are analysed. Time evolution of height and velocity of the ascending prominence are measured. The prominence manifested helical structure and many knots. Large loop of the prominence prior to eruption has been seemingly formed by reconnections. The evolutions of the average pitch angles in the legs of the prominence and near the summit, from pre-eruptive phase to eruptive phase, are measured. The decrease of pitch angle in legs and near the summit of the prominence sugget 'detwisting'. Velocities of five selected knots are also given.