Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
R. Osterbart, T. Blöcker, A.
Men'shchikov, G. Weigelt, Y. Balega and J.M Winters:
Diffraction-limited Bispectrum Speckle
Interferometry of the
Carbon Star IRC+10216 with the SAO 6m Telescope
Astronomische Gesellschaft Meeting Abstracts
(AGM 14, P32)
Poster presented at the Annual Scientific Meeting of the Astronomische
Gesellschaft
at Heidelberg, September 14-19, 1998
Abstract.
We present the first H- and K-band images of the carbon star IRC+10216
with 76 mas resolution. The images were reconstructed from 6 m
telescope
speckle data using the speckle masking bispectrum method.
Several individual components of the circumstellar dust shell can be
resolved
at separations of approximately 100 to 200 mas from the central object.
The dust clouds are located inside a larger nebulosity of a bipolar,
X-shaped structure with an approximate NS polar axis. The
high-resolution
images as well as the SED of the object are compared with results of
2D radiative transfer calculations. The considerable brightness of one
of
the clouds can be explained if we assume that the central star is
heavily
obscured by circumstellar dust clouds.
The radius of the central object was determined to be approximately 25
mas.
Our high-resolution observations obtained at different epochs within
the last 3 years suggest a dynamical evolution of the resolved
structures caused by the expansion of the dust shell. For the
interpretation of the resolved shell structures we
compared our observations with time-dependent model calculations for
carbon-rich circumstellar dust
shells. The fragmentation of the dust shell can most likely be
interpreted
as direct evidence for a mass-loss
process of extreme inhomogeneity, possibly caused by large-scale
surface
convection cells (supergranulation) of red giants discussed by
Schwarzschild.
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