Coordinated monitoring of the eccentric O-star binary Iota Orionis: optical spectroscopy and photometry

With the objective of investigating the wind-wind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-sc ale, coordinated optical monitoring campaign of the massive, highly eccentr ic O9 III+B1 III binary Iota Orionis. Successfully separating the spectra o f the components, we refine the orbital elements and confirm the rapid apsi dal motion in the system. We also see strong interaction between the compon ents during periastron passage and detect phase-locked variability in the s pectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the prediction s of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restr icting the orbital inclination to 50 degrees less than or similar to i less than or similar to 70 degrees.