Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
R. Osterbart, A. Men'shchikov, G.
Weigelt, Y. Balega and N. Langer:
High-resolution Speckle Imaging and
Radiative Transfer Modeling of the Red Rectangle
Astronomische Gesellschaft Meeting Abstracts
(AGM 14, P31)
Poster presented at the Annual Scientific Meeting of the Astronomische
Gesellschaft
at Heidelberg, September 14-19, 1998
Abstract.
We present diffraction-limited optical and NIR images of the Red
Rectangle
reconstructed from ESO/MPG
2.2 m and SAO 6 m telescope data. The unprecedented resolution of 75
mas
was achieved by applying the
speckle masking bispectrum method to the data.
The bipolar structure of the Red Rectangle is visible at all
observed wavelengths. Two bright compact lobes are present in the
center of
the nebula with a separation of approximately 0.15".
A dark dust lane totally obscures the central close binary.
This structure and the X-shape of the nebula on larger scales are
thought to be the result of a rather strong wind clearing the polar
cavities.
Our 2D radiative transfer calculations show that the bipolar appearance
is
caused by a very dense, compact torus with an optical depth of A_V ~30
mag. From a comparison of the observed and theoretical images, we
derived an inclination angle of 7 degrees for the torus.
The model torus has a 1/r^2 dust density
distribution between the inner boundary at 6 AU and R=16 AU (~50 mas),
while at larger distances the
density gradient steepens to approximately 1/r^4.
We derived a lower limit for the total dust mass in the torus of
2x10^-3 Msol.
The radiative transfer calculations show that the best agreement
with all observational constraints can be found if the compact,
massive torus contains predominantly very large (millimeter-sized)
grains.
A much smaller mass of normal (submicron-sized) grains must exist
mainly
in the bipolar outflow regions.
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