Ejection of helical field structures through the outer corona

The May 5, 1980 coronal mass ejection observed by the SMM coronagraph polarimeter contained an eruptive prominence with apparent helical structure. After a general discussion of the morphology of this event, the evolution of the prominence structure as it traversed the outer corona is described. Particular attention is given to the distribution of magnetic helicity, a measure of helical structure. This distribution can be inferred by tracking the crossovers between individual filaments within the prominence. The northern leg of the prominence consisted of two braided H-alpha filaments shredded into subfilaments near the top. Much of the helicity in this leg resided in a compact central region. As the prominence rose, the central region unwound by expanding rapidly along the leg. This expansion could arise from both acceleration of the prominence material and spreading of the distribution of helicity along the leg. 34 references