![]() This paper is the first to combine optical interferometry data from multiple facilities for imaging, and we discuss the challenges and potential for the future of this method, given current calibration and software limitations. We present the first results from an ongoing survey for multiplicity among the bright stars using the Navy Precision Optical Interferometer (NPOI). for the unfunded DIVA (Double Interferometer for Visual As- trometry Rser 1999) and AMEX (Astrometric Mapping Ex- plorer Gaume & Johnston 2003) missions. We point out that dust shell asymmetries, like those observed here, can qualitatively explain the difficulty recent workers have had in simultaneously fitting the broad-band spectral energy distributions and high-resolution spatial information, without invoking unusual dust properties or multiple distinct shells (from hypothetical ``superwinds''). ![]() The measured angular separations p range from 000.091 to 500.93. Deviations from spherically-symmetric mass loss in the red supergiant NML Cyg could be related to recent evidence for dynamically-important magnetic fields and/or stellar rotation. We report 480 astrometric measurements of 468 double stars systems. In addition, 20 high-quality nondetections ofcompanions are reported for stars suspected of being nonsingle byHipparcos. Only one target, WR 48 Mus, was Expand 206 The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry H. In 15cases, relative astrometry is reported for the first time for newlyconfirmed pairs. We present the results of a speckle interferometric survey for close visual companions, mainly among 29 of the apparently brightest Wolf-Rayet (W-R) stars. We find evidence for large-scale inhomogeneities in some dust shells and also significant deviations from uniform brightness for the photospheres of the most evolved M-stars. Astrometry with the VLT Interferometer Astrometry with the. Precision Astrometry with the Space Interferometry Mission - Volume 202 Skip to main content Accessibility help We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Five hundred twelve relative astrometry measures are presented for 253double stars, including 53 double stars discovered by Hipparcos. The unique combination of excellent Fourier coverage at short baselines and high-quality long-baseline fringe data allows us to determine the location and clumpiness of the inner-most hot dust in the envelopes, and to measure the diameters of the underlying stars themselves. The specifications required to operate an astrometric interferometric are particularly stringent on siderostat rotation axes, pupil transfer and instrument stability. We present first results of an experiment to combine data from Keck aperture masking and the Infrared-Optical Telescope Array (IOTA) to image the circumstellar environments of evolved stars with ~20 milliarcsecond resolution. We propose a near-IR demonstration experiment with the two VLTI test siderostats (0.4 m) at Paranal, to be used both in wide-angle single-field and in narrow-angle dual-field astrometry.
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