Ja n 20 04 First results with the IOTA 3 imaging interferometer : The spectroscopic binaries λ Vir and WR 140

We report the first spatially-resolved observations of the spectroscopic binaries λ Vir and WR 140, which includes the debut of aperture-synthesis imaging with the upgraded three-telescope IOTA interferometer. Using IONIC-3, a new integrated optics beam combiner capable of 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 + O4/5) was found to have a separation of ∼13 milli-arcseconds with a position angle consistent with the images of the 2001 dust shell ejection only if the WolfRayet star is fainter than the O star at 1.65μm. We also highlight λ 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. monnier@umich.edu: University of Michigan (Astronomy), 500 Church St, Ann Arbor, MI 48109-1090 Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA, 02138, USA University of Massachusetts, Amherst Michelson Science Center, California Institute of Technology, Pasadena, CA Laboratoire d’Astrophysique de Grenoble, 414 Rue de la Piscine 38400 Saint Martin d’Heres, France Alcatel Space Industries, Cannes, France LETI-CEA, Grenoble, France European Southern Observatory, Germany Massachusetts Institute of Technology, Cambridge, MA IMEP-INPG, Grenoble, France