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

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 solar radii 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(λ1)/V(λ2) 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.

Paper Details

Date Published: 21 February 2003
PDF: 4 pages
Proc. SPIE 4838, Interferometry for Optical Astronomy II, (21 February 2003); doi: 10.1117/12.458659
Show Author Affiliations
Gerd Weigelt, Max-Planck-Institut fuer Radioastronomie (Germany)
Udo Beckmann, Max-Planck-Institut fuer Radioastronomie (Germany)
Jean-Philippe Berger, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Thomas Bloecker, Max-Planck-Institut fuer Radioastronomie (Germany)
Michael K. Brewer, Univ. of Massachusetts/Amherst (United States)
Karl-Heinz Hofmann, Max-Planck-Institut fuer Radioastronomie (Germany)
Marc G. Lacasse, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Victor Malanushenko, Max-Planck-Institut fuer Radioastronomie (Germany)
Rafael Millan-Gabet, Harvard-Smithsonian Ctr. for Astrophysics (United States)
John D. Monnier, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Keiichi Ohnaka, Max-Planck-Institut fuer Radioastronomie (Germany)
Ettore Pedretti, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Dieter Schertl, Max-Planck-Institut fuer Radioastronomie (Germany)
F. Peter Schloerb, Univ. of Massachusetts/Amherst (United States)
Michael Scholz, Univ. Heidelberg (Germany)
Univ. of Sydney (Australia)
Wesley A. Traub, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Boris Yudin, Sternberg Astronomical Institute (Russia)

Published in SPIE Proceedings Vol. 4838:
Interferometry for Optical Astronomy II
Wesley A. Traub, Editor(s)

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