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Near-infrared IOTA interferometry of the symbiotic star CH Cyg

Hofmann, K.-H. and Beckmann, U. and Berger, J. and Blöcker, T. and Brewer, M. K. and Lacasse, M. and Malanushenko, V. and Millan-Gabet, R. and Monnier, J. and Ohnaka, K. and Pedretti, E. and Schertl, D. and Schloerb, P. and Scholz, M. and Traub, W. and Weigelt, G. and Yudin, B. (2003) Near-infrared IOTA interferometry of the symbiotic star CH Cyg. In: Interferometry for Optical Astronomy II. Proceedings of SPIE. No.4838. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, pp. 1043-1046. ISBN 9780819446176.

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We present observations of the symbiotic star CH Cyg with a new JHK-band beam combiner mounted to the IOTA interferometer. The new beam combiner consists of an anamorphic cylindrical lens system and a grism, and allows the simultaneous recording of spectrally dispersed J-, H- and K-band Michelson interferograms. The observations of CH Cyg were conducted on 5, 6, 8 and 11 June 2001 using baselines of 17m to 25m. From the interferograms of CH Cyg, J-, H-, and K-band visibility functions can be determined. Uniform-disk fits to the visibilities give, e.g., stellar diameters of (7.8 ± 0.6) mas and (8.7 ± 0.8) mas in H and K, respectively. Angular stellar filter radii and Rosseland radii are derived from the measured visibilities by fitting theoretical center-to-limb intensity variations (CLVs) of Mira star models. The available HIPPARCOS parallax of CH Cyg allows us to determine linear radii. For example, on the basis of the K-band visibility, Rosseland radii in the range of 214 to 243 solar radii can be derived utilizing CLVs of different fundamental mode Mira models as fit functions. These radii agree well within the error bars with the corresponding theoretical model Rosseland radii of 230 to 282 solar radii. Models of first overtone pulsators are not in good agreement with the observations. The wavelength dependence of the stellar diameter can be well studied by using visibility ratios V(λ1)/V(λ2) since ratios of visibilities of different spectral channels can be measured with higher precision than absolute visibilities. We found that the 2.03 μm uniform disk diameter of CH Cyg is approximately 1.1 times larger than the 2.15 μm and 2.26 μm uniform-disk diameter.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Berger, J.0000-0001-5025-0428
Lacasse, M.0000-0001-8627-9708
Millan-Gabet, R.0000-0003-0447-5866
Monnier, J.0000-0002-3380-3307
Additional Information:© 2003 Society of Photo-optical Instrumentation Engineers (SPIE).
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:interferometry, symbiotic stars, near-infrared
Series Name:Proceedings of SPIE
Issue or Number:4838
Record Number:CaltechAUTHORS:20190118-132427660
Persistent URL:
Official Citation:Karl-Heinz Hofmann, Udo Beckmann, Jean-Philippe Berger, Thomas Bloecker, Michael T. Brewer, Marc G. Lacasse, Victor Malanushenko, Rafael Millan-Gabet, John D. Monnier, Keiichi Ohnaka, Ettore Pedretti, Dieter Schertl, F. Peter Schloerb, Michael Scholz, Wesley A. Traub, Gerd Weigelt, Boris Yudin, "Near-infrared IOTA interferometry of the symbiotic star CH Cyg," Proc. SPIE 4838, Interferometry for Optical Astronomy II, (21 February 2003); doi: 10.1117/12.458904
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92375
Deposited By: Tony Diaz
Deposited On:21 Jan 2019 23:35
Last Modified:16 Nov 2021 03:49

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