Publications of the MPIfR
Optical & Infrared
Interferometry Group
Driebe, T., Riechers, D., Balega, Y.Y.,
Hofmann, K.-H., Men'shchikov, Weigelt, G.
High-resolution near-infrared speckle
interferometry and radiative transfer
modeling of the OH/IR star OH 26.5+0.6
"ESO Astrophysics Symposia"
Proceedings of the ESO Workshop: "The power of
optical/IR interferometry: recent scientific results and 2nd generation
VLTI instrumentation"
April 4-8, 2005 in Garching, Germany
pg.509-510 (2008)
Abstract
We present near-infrared speckle interferometry of the OH/IR star OH
26.5+0.6 in the K’ band obtained with the 6m telescope of the Special
Astrophysical Observatory (SAO) in Oct. 2003. At a wavelength of λ =
2.13 μm the diffraction-limited resolution of 74 mas was attained. The
reconstructed visibility reveals a spherically symmetric, circumstellar
dust shell (CDS) surrounding the central star. In accordance with the
deep silicate absorption feature in the spectral energy distribution
(SED), the drop of the visibility function to a value of 0.36 at the
cutoff frequency indicates a rather large optical depth of the CDS. To
determine the structure and the properties of the CDS of OH 26.5+0.6,
radiative transfer calculations using the code DUSTY[3] were performed
to simultaneously model its visibility and the SED. Since OH 26.5+0.6
is highly variable, the observational data taken into consideration for
the modeling correspond to different phases of the object’s variability
cycle. As in the case of another OH/IR star, OH 104.9+2.4 (see [5] and
Riechers et al., this volume), we used these observational constraints
at different epochs to derive several physical parameters of the
central star and the CDS of OH 26.5+0.6 as a function of phase
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