The Massive Close Binary in the δ Ori A Triple System

Abstract

AbstractWe present an analysis of short-wave, high-dispersion ultraviolet spectra of the triple star δ Ori A from the International Ultraviolet Explorer Satellite’s (IUE) Final Archive. These spectra were cross-correlated against AE Aur to find the components’ radial velocities, which were then used to produce the system’s orbital elements. The long-period tertiary star in the δ Ori A system was not seen in the resulting cross-correlation functions (CCFs). The close binary’s eclipses allow the orbit’s inclination to be estimated by modeling of its Hipparcos light curve. The primary star appears to have a mass of 11.2 M⊙ and the secondary seems to have a mass of 5.6 M⊙, both of which are about 1/3 of the expected values for stars of their MK types. Although we expected the massive close binary in the δ Ori A system to be a pre-Roche lobe overflow (RLOF) system, these masses appear to require that it be a post-RLOF system. The full description of this work, including the tomographic separation of the spectra for the close binary’s components, appears in Harvin et al. (2002).