Line-Broadening in Solar Flares

Abstract

IN Nature of August 13, Bruce¹ contrasts the Zeeman effect and Stark effect as rival causes of line-broadening observed in the spectra of solar flares, and points out that Ellison's own observation, namely, that Hα, Hβ, etc., show smaller widths than Hγ, contradicts the Stark effect hypothesis favoured by Ellison. He argues that the above observation supports the Zeeman effect hypothesis of the broadening of lines in flare spectra. Ellison, in reply, contends that arguments based upon the relative widths of Hα, Hβ, etc., in emission are to be regarded as inconclusive at present on the ground that these lines have not yet been photographed simultaneously in flares.