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 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 Wolf-Rayet 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.

First Results with the IOTA3 Imaging Interferometer: The Spectroscopic Binaries λ Virginis and WR 140

This is the author accepted manuscript. The final version is available from the American Astronomical Society via the DOI in this record.We report the first spatially resolved observations of the spectroscopic binaries λ 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 ~13 mas with a position angle of 152°, consistent with previous interpretations of the 2001 dust shell ejection only if the Wolf-Rayet star is fainter than the O star at 1.65 μm. 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.The authors gratefully acknowledge critical support from SAO, NASA, and NSF (AST 01-38303). E. P. was supported by an SAO Predoctoral Fellowship, J. D. M. by a CfA Fellowship, and R. M.-G., J.-P. B., and S. R. through NASA Michelson Fellowships. G. T. acknowledges partial support from NASA’s MASSIF SIM Key project (JPL 1240033). In addition, we acknowledge useful contributions from B. Arezki, A. Delboulbe, C. Gil, S. Gluck, E. Laurent, R. B. Metcalf, and E. Tatulli. IONIC-3 was developed by LAOG and LETI in the context of the IONIC collaboration (LAOG, IMEP, LETI), funded by the CNRS and CNES (France). This publication makes use of data products from the Two Mass All Sky Survey, which is a joint project of the University of Massachusetts and IPAC/Caltech, funded by NASA and the NSF. This research has also used the SIMBAD database, NASA’s ADS Service, and services of the Michelson Science Center at Caltech