Publications
of the
MPIfR Optical & Infrared Interferometry Group

G. Weigelt, U. Beckmann, T. Blöcker, K.-H. Hofmann, K. Ohnaka, D. Schertl, M. Brewer, P. Schloerb, Y.N. Efimov, V. Shenavrin, B. Yudin, J.-P. Berger, M. Lacasse, R. Millan-Gabet, J. Monnier, S. Morel, E. Pedretti, W. Traub, V. Malanushenko, B. Mennesson, M. Scholz

Spectro-interferometry of the Mira star T Cep with the IOTA interferometer and comparison with models

Astronomische Gesellschaft Abstract Series (AGM 19, P47)
Der kosmische Materiekreislauf
Annual Scientific Meeting of the Astronomische Gesellschaft, Sep 23-28, 2002, Berlin, Germany

Abstract

Our new IOTA JHK-band beam combiner allows the simultaneous recording of spectrally dispersed J-, H-, and K-band Michelson interferograms. We present our IOTA observations of the Mira star T Cep with this beam combiner (observations in June 6, 9, 10 and 11 ,2001). The beam combiner optics consists of an anamorphotic cylindrical lens system and a prism. From the JHK interferograms of T Cep we derive the visibilities and the J-, H-, and K-band visibility functions and the uniform-disk diameters of 14.0 mas, 13.7 mas and 15.0 mas, respectively. Angular stellar filter radii and Rosseland radii are derived from the measured visibilities by fitting different theoretical center-to-limb intensity variations (CLVs) of different Mira star models. The available HIPPARCOS parallax of T Cep allows us to determine linear radii. For example, from the K-band visibility we derive a Rosseland radius of 329+70-50 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.