ABUNDANCE RATIOS OF OXYGEN, NEON, AND MAGNESIUM IN SOLAR ACTIVE REGIONS AND FLARES - THE FIP EFFECT

Relative abundances of oxygen, neon, and magnesium have been derived f or a sample of nine solar active regions, flares, and an erupting prom inence by combining plots of the ion differential emission measures. T he observations were photographed in the 300-600 Angstrom range by the NRL spectroheliograph on Skylab. Methods for deriving the Mg/Ne abund ance ratio-which measures the separation between the low-FIP and high- FIP abundance plateaus-have been described in previous papers. In this paper we describe the spectroscopic methods for deriving the O/Ne abu ndance ratio, which gives the ratio between two high-FIP elements.The plot of the O/Ne ratio versus the Mg/Ne ratio in the sample of nine Sk ylab events is shown. The variation in the Mg/Ne ratio by a factor of 6 is associated with a much smaller range in the O/Ne ratio. This is b roadly consistent with the presence of the standard FIP pattern of abu ndances in the outer atmosphere of the Sun. However, a real change in the relative abundances of oxygen and neon by a factor of 1.5 cannot b e excluded.