P45	March 2000

¹ Département de Physique, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada, and Observatoire du Mont Mégantic
² Institut d'Astrophysique et de Géophysique - Université de Liège, Avenue de Cointe 5, 4000 Liège, Belgium
³ Moscow State University, Sternberg State Astronomical Institute, Universitetskij Prospect 13, 119899, Moscow, Russia
⁴ Observatoire de Paris-Meudon, DASGAL, F-92125 Meudon Principal Cedex, France
⁵ Universities Space Research Association/Laboratory for High Energy Astrophysics, GSFC, Greenbelt, MD 20771, USA
⁶ Instituto de Astronomía, Universidad Nacional Autónoma de México, J. J. Tablada 1006, Colonia Lomas de Santa Maria, 58090 Morelia, Michoacán, México
⁷ University of Iowa, Iowa City, IA 52245
⁸ Ritter Observatory, The University of Toledo, Toledo, OH 43606, USA
⁹ Observatorio de La Plata, 1900 La Plata, Argentina
¹⁰ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
¹¹ Institut d'Astrophysique, 98bis boulevard Arago, 75014 Paris, France

^* Chargé de Recherches FNRS, Belgium

Abstract

     With the objective of investigating the wind-wind collision phenomenon and supporting contemporaneous X-ray observations (cf. Pittard et al. 2000), we organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9III+B1III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50° i 70°.