The Auroral Green Line 5577

Abstract

MESSRS. McLennan, McLeod and McQuarrie have published in NATURE, vol. 118, page 441 (Sept. 25, 1926) the results of some recent experiments on the origin of the auroral green line 5577. During July and August last, while a guest of the Nela Park Research Laboratory, at the kind invitation of Dr. W. E. Forsythe, I had the opportunity of investigating spectroscopically the electrical discharge in mixtures of (1) helium with oxygen, and (2) argon with oxygen. The relative proportions of the two gases in each mixture were varied as well as the current through the gases. In the case of helium with oxygen, traces of this green line were found on some plates, but its intensity was usually very feeble. In one experiment, however, with argon and oxygen, the line 5577 appeared very strongly, about one-half the intensity of the argon line 5559, the iron arc spectrum being used for comparison (Fig. 1. I am indebted to Prof. Lloyd for the enlargement).