Triple star delta Ori radial velocities

Consequently, we found that the component masses according to the three-body model are 17.8, 8.5, and 8.7 solar masses, for Aa1, Aa2, and Ab, respectively, with the uncertainties of the order of 1 solar mass. We used new photometry from the BRITE satellites together with astrometry, radial velocities, eclipse timings, eclipse duration, spectral line profiles, and spectral energy distribution to refine radiative properties.

The components, classified as O9.5 II + B2 V + B0 IV, have radii of 13.1, 4.1, and 12.0 solar radii, which means that Delta Ori A is a pre-mass-transfer object. The frequency of 0.478 cycles per day, known from the Fourier analysis of the residual light curve and X-ray observations, was identified as the rotation frequency of the tertiary. Delta Ori could be related to other bright stars in Orion, in particular, Zeta Ori, which has a similar architecture, or Epsilon Ori, which is a single supergiant, and possibly a post-mass-transfer object.