Radial Velocities of Cepheid Variable Stars in the Southern Hemisphere

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Abstract
Radial velocity determinations have been made on a uniform system for 55 cepheid variables in the Southern Hemisphere. Velocity curves Have been drawn from 830 observations secured at phases well distributed over the light curves of the variables, and the normal velocities have been determined graphically by the method of equal areas. The plates for radial velocity were obtained with the Cassegrain spectrograph of the 74-inch Radcliffe reflector, the dispersion of the spectrograms being 49 A/mm at Hγ. The velocity system to which the determinations refer has been examined by means of 39 spectrograms of 9 standard velocity stars, mostly giants, and 46 spectrograms of 9 supergiants obtained during the cepheid programme. The Radcliffe velocities of the standard velocity stars were found to be in very satisfactory agreement with velocities on the Lick System. The radial velocity observations presented in the paper complete an extension of Joy's work to southern cepheids, with photographic magnitudes brighter than 10m.5 at minimum light, contained within a hitherto largely unobserved quadrant of galactic longitude.

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