Intensities of Hydrogen H and Helium D3 in Prominences

Abstract

The observational procedure is described by which equivalent widths of Hα and D ₃ and their local variations in prominences are determined. First results for nine prominences are in good agreement with earlier observations of Minnaert and Slob. Within one and the same prominence the intensity ratio Hα /D ₃ is found to decrease with increasing intensity of D ₃ , indicating the effect of self-absorption on Hα . In the brightest prominence here investigated Hα is about eight times fainter than it would be without that effect being present. Intensities of Hα when plotted against intensities of D ₃ are consistent with the theoretical curve of growth which corresponds to thermal motion without turbulence.