First results with the IOTA3 imaging interferometer: The spectroscopic binaries lambda Virginis and WR 140

We report the first spatially resolved observations of the spectroscopic binaries lambda Vir and WR 140, including the debut of aperture-synthesis imaging with the upgraded three-telescope IOTA interferometer. Using IONIC-3, a new integrated optics beam combiner capable of a precise closure phase measurement, short observations were sufficient to extract the angular separation and orientation of each binary system and the component brightness ratio. Most notably, the underlying binary in the prototypical colliding-wind source WR 140 (WC7 + O4/O5) was found to have a separation of similar to 13 mas with a position angle of 152degrees, consistent with previous interpretations of the 2001 dust shell ejection only if the Wolf-Rayet star is fainter than the 0 star at 1.65 mum. We also highlight lambda Vir, whose peculiar stellar properties of the Am star components will permit direct testing of current theories of tidal evolution when the full orbit is determined.