Springer Online Journal Archives 1860-2000
Abstract Spectroheliograms in the Lα Mg xii line and in the Mg xi resonance (R) 1s 21 S 0-1s2p 1 P 1 line, intercombination (I) 1s 21 S 0-1s2p 3 P 1,2, line, and the forbidden (F) 1s 21 S 0-1s2s 3 S 1 line, have been obtained. Two Bragg crystal spectrometers were used mounted with mechanical collimators to obtain a spatial resolution of 1′ × 3′. The apparatus was launched on a sounding rocket on July 2nd, 1971. A particularly thorough study was made of the brightest active region (MC 11402). Variations in the F to I Mg xi line intensity ratio from one point to another in the active region did not reveal the presence of high electron densities. The observed intensities of the Mg xi R line, Mg xii Lα line and Mg x 1s 22s 2 S 1/2-1s2p 1 P 2s × × 2 P11/2, 3/2 S line are not well explained by an isothermal model. Good agreement between computed and observed intensities is obtained using the non-isothermal model proposed here.
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