Publications of the MPIfR
Optical & Infrared
Interferometry Group
D. Riechers, T. Driebe, Y. Balega,
K.-H. Hofmann, A. B. Men'shchikov, and G. Weigelt
High-Resolution Near-Infrared Speckle
Interferometry and Radiative Transfer Modeling of the OH/IR star
OH 104.9+2.4
"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.505-506 (2008)
Abstract
We present near-infrared speckle interferometry of the OH/IR star OH
104.9+2.4 in the K’ band obtained with the 6m telescope of the Special
Astrophysical Observatory (SAO) in Sep. 2002 and Oct. 2003. At a
wavelength of λ = 2.13 μ m the diffraction-limited resolution of 74 mas
was attained. The reconstructed visibility reveals a spherically
symmetric, circumstellar dust shell (CDS) surrounding the central star.
The visibility function shows that the stellar contribution to the
total flux at λ = 2.13 μ m is less than 30% at all phases, indicating a
rather large optical depth of the CDS. The azimuthally averaged
1-dimensional Gaussian visibility fit yields a diameter of 47 ± 3 mas
(FHWM), which corresponds to 112 ± 13 AU for an adopted distance of D =
2.38 ± 0.24 kpc.To determine the structure and the roperties of the CDS
of OH 104.9+2.4, radiative transfer calculations using the code DUSTY
cite{rie:ie95} were performed to simultaneously model its visibility
and the spectral energy distribution (SED). Since OH 104.9+2.4 is
highly variable, the observational data taken into consideration for
the modeling correspond to different phases of the object’s variability
cycle. This offers the possibility to derive several physical
parameters of the central star and its CDS as a function of phase.
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