Abstract
A close examination of spectrograms of Be and B-type stars obtained at the Perkins Observatory has revealed a surprising percentage of stars of the nebulous-line classification which exhibit sharp lines also. The present study differs in approach from that of Struve and Wurm1 in that the present study is based exclusively upon the appearance of the visual region of the spectrum. Struve and Wurm examined the photographic region of the spectra of several hundred B-type stars, but they were able to detect sharp lines in only a small percentage of the class η stars. The results here presented are based upon a file of B-type spectra secured by the writer in the visual region of the spectrum, prior to December 1938, with the Yerkes auto-collimating spectrograph attached to the 69-inch Perkins Reflector. Most of these plates were taken during the course of a survey program comprising a search for new Be stars, and, consequently, most of the spectra are recorded on high-speed emulsion and are unsuited to a study of faint, narrow lines. However, plates of sufficiently good quality were found for 18 stars, and 13 of these exhibited both nebulous and sharp lines in their visual spectra. Eleven of the new super-shell stars had already been classified as nebulous line objects, and five of them were known Be stars.
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