ASTRONOMY AND ASTROPHYSICS Diffraction - limited Speckle - Masking Interferometry of the Red Supergiant VY CMa ⋆

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 ∼ 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×83 mas, 80 mas×116 mas and 138 mas×205 mas, respectively, or 100 AU × 125 AU, 120 AU × 174 AU and 207 AU × 308 AU (for a distance of 1500 pc). We discuss several interpretations for the asymmet-ric 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.