Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
M. Wittkowski, N. Langer and G.
Weigelt:
Diffraction-limited speckle-masking
interferometry of the red supergiant VY CMa
Astronomy and Astrophysics 340, L39-42 (1998)
Abstract.
We present the first diffraction-limited
images of the mass-loss envelope of the red supergiant star VY CMa.
The two-dimensional optical and NIR images were reconstructed from 3.6m
telescope speckle data using bispectrum speckle interferometry.
At the wavelengths 0.8 micron (RG780 filter), 1.28 micron and
2.17 micron the diffraction-limited resolutions of 46mas, 73mas, and
124mas were achieved.
All images clearly show that the circumstellar envelope of VY CMa is
non-spherical.
The RG780, 1.28 micron, and 2.17 micron FWHM Gauss fit diameters are
67mas x 83mas, 80mas x 116mas and 138mas x 205mas,
respectively, or 100 AU x 125 AU, 120 AU x 174 AU and 207 AU x 308 AU
(for a distance of 1500pc).
We discuss several interpretations for the asymmetric morphology.
Combining recent results about the angular
momentum evolution of red supergiants and their pulsational properties,
we suggest that VY CMa is an immediate progenitor of IRC+10420,
a post red supergiant during its transformation into a Wolf-Rayet star.
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