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

G. Weigelt; U. Beckmann; J.-P. Berger; T. Bloecker; M.~K. Brewer; K.-H. Hofmann; M.~G. Lacasse; V. Malanushenko; R. Millan-Gabet; J.~D. Monnier; K. Ohnaka; E. Pedretti; D. Schertl; F.~P. Schloerb; M. Scholz; W.~A. Traub; B. Yudin

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

G. Weigelt, U. Beckmann, J.-P. Berger, T. Bloecker, M.~K. Brewer, K.-H. Hofmann, M.~G. Lacasse, V. Malanushenko, R. Millan-Gabet, J.~D. Monnier, K. Ohnaka, E. Pedretti, D. Schertl, F.~P. Schloerb, M. Scholz, W.~A. Traub, B. Yudin

School of Engineering & Physical Sciences

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

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.

Original language	Undefined/Unknown
Title of host publication	Interferometry for Optical Astronomy II
Editors	W.~A. Traub
Pages	181-184
Number of pages	4
Volume	4838
Publication status	Published - 24 Feb 2003

Publication series

Name	Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series

Cite this

Weigelt, G., Beckmann, U., Berger, J.-P., Bloecker, T., Brewer, M. K., Hofmann, K.-H., Lacasse, M. G., Malanushenko, V., Millan-Gabet, R., Monnier, J. D., Ohnaka, K., Pedretti, E., Schertl, D., Schloerb, F. P., Scholz, M., Traub, W. A., & Yudin, B. (2003). JHK-band spectro-interferometry of T Cep with the IOTA interferometer. In W. A. Traub (Ed.), Interferometry for Optical Astronomy II (Vol. 4838, pp. 181-184). (Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series).

@inproceedings{c39138215959424db919b564fb29f1d4,

title = "JHK-band spectro-interferometry of T Cep with the IOTA interferometer",

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.",

author = "G. Weigelt and U. Beckmann and J.-P. Berger and T. Bloecker and M.~K. Brewer and K.-H. Hofmann and M.~G. Lacasse and V. Malanushenko and R. Millan-Gabet and J.~D. Monnier and K. Ohnaka and E. Pedretti and D. Schertl and F.~P. Schloerb and M. Scholz and W.~A. Traub and B. Yudin",

year = "2003",

month = feb,

day = "24",

language = "Undefined/Unknown",

volume = "4838",

series = "Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series",

pages = "181--184",

editor = "W.~A. Traub",

booktitle = "Interferometry for Optical Astronomy II",

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Weigelt, G, Beckmann, U, Berger, J-P, Bloecker, T, Brewer, MK, Hofmann, K-H, Lacasse, MG, Malanushenko, V, Millan-Gabet, R, Monnier, JD, Ohnaka, K, Pedretti, E, Schertl, D, Schloerb, FP, Scholz, M, Traub, WA & Yudin, B 2003, JHK-band spectro-interferometry of T Cep with the IOTA interferometer. in WA Traub (ed.), Interferometry for Optical Astronomy II. vol. 4838, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, pp. 181-184.

JHK-band spectro-interferometry of T Cep with the IOTA interferometer. / Weigelt, G.; Beckmann, U.; Berger, J.-P. et al.
Interferometry for Optical Astronomy II. ed. / W.~A. Traub. Vol. 4838 2003. p. 181-184 (Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - JHK-band spectro-interferometry of T Cep with the IOTA interferometer

AU - Weigelt, G.

AU - Beckmann, U.

AU - Berger, J.-P.

AU - Bloecker, T.

AU - Brewer, M.~K.

AU - Hofmann, K.-H.

AU - Lacasse, M.~G.

AU - Malanushenko, V.

AU - Millan-Gabet, R.

AU - Monnier, J.~D.

AU - Ohnaka, K.

AU - Pedretti, E.

AU - Schertl, D.

AU - Schloerb, F.~P.

AU - Scholz, M.

AU - Traub, W.~A.

AU - Yudin, B.

PY - 2003/2/24

Y1 - 2003/2/24

N2 - 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.

AB - 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.

M3 - Conference contribution

VL - 4838

T3 - Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series

SP - 181

EP - 184

BT - Interferometry for Optical Astronomy II

A2 - Traub, W.~A.

ER -