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

We have measured nonzero closure phases for about 29% of our sample of 56 nearby asymptotic giant branch (AGB) stars, using the three-telescope Infrared Optical Telescope Array (IOTA) interferometer at near-infrared wavelengths (H band) and with angular resolutions in the range 5-10 mas. These nonzero closure phases can only be generated by asymmetric brightness distributions of the target stars or their surroundings. We discuss how these results were obtained and how they might be interpreted in terms of structures on or near the target stars. We also report measured angular sizes and hypothesize that most Mira stars would show detectable asymmetry if observed with adequate angular resolution.

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.

We describe the new control system for the PICNIC near-infrared camera and the visible star tracker, implemented at the IOTA interferometer, based on the ALTERA Complex Programmable Logic Device (CPLD) technology. These digital components provide an adaptive interface between the control system and the cameras used at IOTA, allowing flexibility when connecting very different devices. In particular the clocking and processing circuits used for the PICNIC camera can be changed in milliseconds during normal operation. The camera can then switch between full quadrant readout mode used for alignment and diagnostics, and a N pixel readout mode used for science operation.

New beam combination techniques, using two and three telescopes, have been the focus of activity at IOTA during the past two years since our last update.(1) In particular, we have added a third telescope, made closure-phase measurements, demonstrated two- and three-beam combination with integrated optics combiners, demonstrated two-beam combination with an asymmetric coupler, and made simultaneous JHK visibility measurements with an image-plane combiner.

We derive HOCO+ column densities approximately 10(15) cm-2 toward the Galactic center and < or = 10(12) cm-2 for cold dark clouds from observations and an LVG model. We mapped the HOCO+ 4(04)-3(03) line toward Sgr A. The fractional abundance of HOCO+ in the Galactic center region is three orders of magnitude larger than predicted by quiescent ion-molecule chemistry and an order of magnitude larger than predicted by a MHD shock model. If HOCO+ traces interstellar CO2, the implied high abundance ([CO2] approximately [CO]) in the Galactic center may result from UV photolysis of grain mantles.

We describe a new near-infrared camera based on the PICNIC array for the Infrared-Optical Telescope Array (IOTA). The camera control is based on a complex programmable logic device (CPLD). This architecture allows fast and stable clocking of the PICNIC array, resulting in faster and lower-noise readout. The CPLD architecture also allows on-the-fly reconfiguration of the readout circuit. We demonstrate this capability with the implementation of circuits dedicated to two different functions: imaging used for alignment purposes, and fast sequential readout of a few pixels used for interference fringe detection. In fringe detection mode, the measured rms readout noise for a single read of the detector is σsingle−read = 8.7± 0.6 electron. In data-acquisition mode, the signal is the difference of two successive reads, so the noise on this signal is larger by √ 2, giving σread = 12.4± 0.8 elec. Smithsonian Predoctoral Fellow College de France, Place Marcellin Berthelot, Paris, France LISE, Observatoire de Haute Provence, Saint Michel l’ Observatoire, France Now at Michelson Science Center, California Institute of Technology, Pasadena, CA Now at University of Michigan, Ann Arbor, MI Now at Laboratoire d’ Astrophysique de Grenoble, France