Spectroscopic study of the triple system Xi Cephei

The primary star of the common proper-motion pair xi Cep has been found to be a double-lined spectroscopic binary. Orbital elements have been derived for the spectroscopic system using DAO coude plates. The systemic velocity is the same as that of the visual secondary, and thus confirms the physical nature of the wide pair. Relative luminosities have been derived for the spectroscopic pair by Petrie's method, and the spectral types of the components have been estimated by comparison of line-strength ratios with those of standard stars, and confirmed by fitting the observed colors. This paper includes a brief discussion of several possible evolutionary models of the system