X-rays spectroheliograms in lines of Mg xi and Mg xii

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 P1_{1/2, 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.