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Astron. Astrophys. 340, L39-L42 (1998)

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Letter to the Editor

Diffraction-limited speckle-masking interferometry of the red supergiant VY CMa *

M. Wittkowski 1, N. Langer 2 and G. Weigelt 1

1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
2 Institut für Physik, Universität Potsdam, D-14415 Potsdam, Germany

Received 26 August 1998 / Accepted 27 October 1998


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 3.6 m telescope speckle data using bispectrum speckle interferometry. At the wavelengths [FORMULA] 0.8 µm (RG 780 filter), 1.28 µm, and 2.17 µm the diffraction-limited resolutions of 46 mas, 73 mas, and 124 mas were achieved. All images clearly show that the circumstellar envelope of VY CMa is non-spherical. The RG 780, 1.28 µm, and 2.17 µm FWHM Gauss fit diameters are 67 mas[FORMULA]83 mas, 80 mas[FORMULA]116 mas and 138 mas[FORMULA]205 mas, respectively, or [FORMULA], [FORMULA] and [FORMULA] (for a distance of 1500 pc). 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 +10 420, a post red supergiant during its transformation into a Wolf-Rayet star.

Key words: techniques: interferometric – stars: supergiants – stars: late-type – stars: mass-loss – stars: individual: VY CMa

* Based on data collected at the European Southern Observatory, La Silla, Chile

Correspondence to: Markus Wittkowski (e-mail: mw@speckle.mpifr-bonn.mpg.de)

© European Southern Observatory (ESO) 1998

Online publication: November 9, 1998