Plaskett's star photographic spectra from DAO

The location of the peak that is associated with the secondary in cross-correlation functions changes with time near phase 0.75, although the mean amplitude of the radial velocity curve of the secondary did not change between the two campaigns. There is also an offset in velocities of the primary measured from H{gamma} and He i {lambda}4472 near phase 0.25. The velocity curves of the components suggest a mass ratio that is larger than previous estimates, although uncertainties associated with the spectroscopic features attributed to the secondary, coupled with the wavelength resolution of the spectra, complicate efforts to determine robust masses.

We conclude that the peculiarities in the radial velocity curves of the components have thus been in place for over a thousand orbital cycles.