iota Orionis-evidence for a capture origin binary

The star i Ori (HD 37043, HR 1899) is a 29.1338 day period, double-lined O- type spectroscopic binary with a highly eccentric orbit. The classification of the primary (O9 III) is well established. The secondary, roughly 2 mag fainter, is generally acknowledged as an early-type B star, but claims abou t its luminosity class have been made only from its estimated light contrib ution and not from its spectrum. We have collected visual data with the 1 m Multiple-Telescope Telescope (MTT; at the Center for High Angular Resoluti on at Georgia State University) in four wave bands well distributed in orbi tal phase, with the periastron passage particularly well covered. We presen t reconstructed component spectra from our tomographic reconstruction techn ique. According to three Morgan-Keenan (MK) luminosity criteria, we can una mbiguously characterize the secondary as a B1 III-IV giant (MK type or B0.8 III-IV interpolated type). We also have constructed three line-strength in dices from eighteen observed individual lines for the secondary and a grid of comparison stars. These results confirm the typing from the MK luminosit y criteria. Furthermore, we argue, from the mass ratio (q = 0.5), evolution ary considerations, the orbital scale, and the unremarkable CNO element equ ivalent widths of the secondary, that this system is not coevolved nor has it undergone significant mass transfer. We postulate an origin for the syst em in a binary-binary collision and suspect that the runaway stars mu Col a nd AE Aur may have been the original partners for the current i Ori seconda ry and primary, respectively.