The Visual Orbit of Pegasi

We have determined the visual orbit for the spectroscopic binary ι Pegasi with interferometric visibility data obtained by the Palomar Testbed Interferometer in 1997. ι Peg is a double-lined binary system whose minimum masses and spectral typing suggests the possibility of eclipses. Our orbital and component diameter determinations do not favor the eclipse hypothesis: the limb-to-limb separation of the two components is 0.151±0.069 mas at conjunction. Our conclusion that the ι Peg system does not eclipse is supported by high-precision photometric observations. The physical parameters implied by our visual orbit and the spectroscopic orbit of Fekel & Tomkin are in good agreement with those inferred by other means. In particular, the orbital parallax of the system is determined to be 86.9±1.0 mas, and masses of the two components are determined to be 1.326±0.016 and 0.819±0.009 M, respectively.

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