IOTA observation of the circumstellar envelope of R CrB

Keiichi Ohnaka, Udo Beckmann, Jean-Philippe Berger, Michael K. Brewer, Karl-Heinz Hofmann, Marc G. Lacasse, Victor Malanushenko, Rafael Millan-Gabet, John D. Monnier, Ettore Pedretti, Dieter Schertl, F. Peter Schloerb, Victor Shenavrin, Wesley A. Traub, Gerd Weigelt, Boris Yudin

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We report the first long-baseline interferometric observations of R CrB. The observations were carried out at the Infrared Optical Telescope Array (IOTA), using our new JHK beam combiner which enables us to record fringes simultaneously in the J-, H-, and K-bands. The circumstellar envelope of R CrB is resolved at a baseline of 21 m, and the K-band visibility is derived to be 0.61 +/- 0.03 along a position angle of about 170 degrees. The visibility obtained with IOTA, as well as speckle visibilities with baselines up to 6 m and the spectral energy distribution (SED), are fitted with 2-component models consisting of the central star and an optically thin dust shell. The K-band visibilities predicted by the models are about 10% smaller than the visibility obtained with IOTA. However, given the simplifications adopted in our models and the complex nature of the object, this can be regarded as rough agreement. As a hypothesis to explain the small discrepancy, we propose that there might be a group of newly formed dust clouds, which might appear as a third visibility component.
Original languageEnglish
Pages (from-to)1068-1071
JournalInterferometry for Optical Astronomy II
Publication statusPublished - 1 Feb 2003

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    Ohnaka, K., Beckmann, U., Berger, J-P., Brewer, M. K., Hofmann, K-H., Lacasse, M. G., Malanushenko, V., Millan-Gabet, R., Monnier, J. D., Pedretti, E., Schertl, D., Schloerb, F. P., Shenavrin, V., Traub, W. A., Weigelt, G., & Yudin, B. (2003). IOTA observation of the circumstellar envelope of R CrB. Interferometry for Optical Astronomy II, 4838, 1068-1071.