STUDIES OF EARLY-TYPE VARIABLE-STARS .8. THE MASSIVE BINARY-SYSTEM CC-CASSIOPEIAE

New spectroscopic observations, obtained between 1971 and 1988, are presented of the massive O-type binary system CC Cas. Contrary to results from a number of photometric studies during this interval, no clear evidence is found for period changes in this system. The observed variability in the shape of the light curve remains however, as does the one report of detected radio flares, and the well-established stellar-wind mass loss. A solution is attempted of light curves defined by only sparse photometric observations, utilizing the new spectroscopic mass ratio, the temperatures of both components defined by the uvby data, the MK classifications and the spectral line strengths of both stars determined from a tomographic separation procedure. The system is found to be detached, with the two components within the main sequence band and on the same isochrone line in the (log m-log g) diagram at an age of (7 +/- 1) 10(6) yr. In the age analysis we avoided using log T(e) because of what we consider an unresolved problem with the effective temperature scale for O stars. Previously unpublished differential V magnitudes made by Hill at the Mt Kobau Observatory are also published. An appeal is made for accurate photometric monitoring of this bright 3.4-day binary system in order to establish more precise radii and luminosities for the components, and to determine the form of the intrinsic variability.