TY - JOUR
T1 - JHK-band spectro-interferometry of T Cep with the IOTA interferometer
AU - Weigelt, Gerd
AU - Beckmann, Udo
AU - Berger, Jean-Philippe
AU - Bloecker, Thomas
AU - Brewer, Michael K.
AU - Hofmann, Karl-Heinz
AU - Lacasse, Marc G.
AU - Malanushenko, Victor
AU - Millan-Gabet, Rafael
AU - Monnier, John D.
AU - Ohnaka, Keiichi
AU - Pedretti, Ettore
AU - Schertl, Dieter
AU - Schloerb, F. Peter
AU - Scholz, Michael
AU - Traub, Wesley A.
AU - Yudin, Boris
PY - 2003/2/1
Y1 - 2003/2/1
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(¿1)/V(¿2) to investigate the
wavelength dependence of the stellar diameter. We find that the 2.03
¿m uniform-disk diameter of T Cep is about 1.26 times larger than the
2.26 ¿m 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(¿1)/V(¿2) to investigate the
wavelength dependence of the stellar diameter. We find that the 2.03
¿m uniform-disk diameter of T Cep is about 1.26 times larger than the
2.26 ¿m uniform-disk diameter.
M3 - Article
VL - 4838
SP - 181
EP - 184
JO - Interferometry for Optical Astronomy II
JF - Interferometry for Optical Astronomy II
ER -