Multi-epoch photometry of {delta} Ori

However, in 2002 radial-velocity curves of both binary components derived from the IUE and optical spectra using the cross-correlation technique have been published by Harvin et al. (2002ApJ...565.1216H); surprisingly low masses of 11.2 and 5.6M_{sun}_ were obtained. We obtained new spectra in the red spectral region and new UBV photometry.

Using all published photometry and radial velocities, we deduced more accurate orbital and apsidal line periods. The main result of this paper is to show that the observed line spectra of {delta} Ori are composed of the lines of the O9.5 II primary and a similarly hot tertiary, while the lines of a cooler B-type secondary are too faint to be detected in the available spectra. The character of the light curve (low-amplitude partial eclipses and a non-negligible scatter of the data) does not allow for a unique light-curve solution.