Radial Velocities
When the 72-inch telescope was in course of design and construction, one of the greatest needs in astronomical work was increased data in regard to the radial velocities of the stars. Although the telescope was so designed as to be suitable for all kinds of observational work, special attention was devoted to the spectroscopic end. After consultation with the most prominent astronomers an observing programme of about 800 stars whose “proper” or cross motions across the sky were accurately known but whose radial velocities had not been determined, was prepared and spectroscopic observations of the stars on this programme were commenced as soon as the telescope was completed in May 1918. After slightly over three years’ work, observation and measurement were completed and Vol. II, No. 1 of the observatory publications, “The Radial Velocities of 594 Stars,” was published early in 1922. As hitherto the radial velocities of only about 2,000 stars had been obtained, this work was a considerable addition to existing data about the motions of the stars and will be of great use in extending our knowledge of the structure and motions of the universe. A second programme of 1,500 stars has been prepared but owing to other intervening observational work, not much has yet been done on this new programme.
One of the auxiliary programmes undertaken and nearly completed since the first programme is the determination of the radial velocities of a very interesting but limited class of stars, the highest temperature stars known, the O-type stars. The radial velocities and other interesting data about 50 of these stars have been completed.