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JHK-band spectro-interferometry of T Cep with the IOTA interferometer

Weigelt, G. and Beckmann, U. and Berger, J. and Blöcker, T. and Brewer, M. K. and Hofmann, K.-H. 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 Yudin, B. (2003) JHK-band spectro-interferometry of T Cep with the IOTA interferometer. In: Interferometry for Optical Astronomy II. Proceedings of SPIE. No.4838. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, pp. 181-184. ISBN 9780819446176.

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Our new IOTA JHK-band beam combiner allows the simultaneous recording of spectrally dispersed J-, H- and K-band Michelson interferograms. In this paper we present our IOTA observations of the Mira star T Cep with this beam combiner (observations in June 2001; four baselines in the range of 14 m to 27 m). The beam combiner optics consists of an anamorphic cylindrical lens system and a prism. From the interferograms of T Cep we derive the visibilities and the J-, H-, and K-band uniform-disk diameters of 14.0 ± 0.6 mas, 13.7 ± 0.6 mas and 15.0 ± 0.6 mas, respectively. Angular stellar filter radii and Rosseland radii are derived from the measured visibilities by fitting theoretical center-to-limb intensity variations (CLVs) of different Mira star models. The available HIPPARCOS parallax (4.76 ± 0.75 mas) of T Cep allows us to determine linear radii. For example, from the K-band visibility we derive a Rosseland radius of 329_(-50)/^(+70)⊙ if we use the CLVs of the M-models as fit functions. This radius is in good agreement with the theoretical M-model Rosseland radius of 315 solar radii. The comparison of measured stellar parameters (e.g. diameters, effective temperature, visibility shape) with theoretical parameters indicates whether any of the models is a fair representation of T Cep. The ratios of visibilities of different spectral channels can be measured with higher precision than absolute visibilities. Therefore, we use the visibility ratios V(λ_1)/V(λ_2) to investigate the wavelength dependence of the stellar diameter. We find that the 2.03 μm uniform-disk diameter of T Cep is about 1.26 times larger than the 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).
Subject Keywords:interferometry, Mira stars, near-infrared
Series Name:Proceedings of SPIE
Issue or Number:4838
Record Number:CaltechAUTHORS:20190115-111457389
Persistent URL:
Official Citation:Gerd Weigelt, Udo Beckmann, Jean-Philippe Berger, Thomas Bloecker, Michael K. Brewer, Karl-Heinz Hofmann, 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, Boris Yudin, "JHK-band spectro-interferometry of T Cep with the IOTA interferometer," Proc. SPIE 4838, Interferometry for Optical Astronomy II, (21 February 2003); doi: 10.1117/12.458659
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92283
Deposited By: Tony Diaz
Deposited On:15 Jan 2019 21:54
Last Modified:16 Nov 2021 03:48

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