Diffraction-limited 76 mas speckle-masking interferometry of the carbon star IRC+10216 and related AGB objects with the SAO 6m telescope

G. Weigelt, T. Blöcker, K.-H. Hofmann, R. Osterbart, Y. Balega, A.J. Fleischer, and J.M. Winters

Contributed talk presented at the IAU Symposium 191: AGB Stars, August 27th - September 1st 1998, Montpellier, France

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Abstract:

We present high-resolution J-, H-, and K-band observations of the carbon star IRC+10216. The images were reconstructed from 6 m telescope speckle interferograms using the speckle masking bispectrum method. The H image has the unprecedented resolution of 70 mas. The H and K images consist of at least five dominant components within a 0.21 arcsec radius and a fainter asymmetric nebula. The J-, H-, and K- band images seem to have an X-shaped bipolar structure. A comparison of our images from 1995, 1996, 1997, and 1998 shows that the separation of the two brightest components A and B increased from ~193 mas in 1995 to ~246 mas in 1998.

The cometary shapes of component A in the H and J images and the 0.79 µm and 1.06 µm HST images suggest that the core of A is not the central star, but the southern (nearer) lobe of the bipolar structure. The position of the central star is probably at or near the position of component B, where the H-K color has its largest value of H-K = 4.2.

If the star is located at or near B, then the components A, C, and D are located close to the inner boundary of the dust shell at separations of ~200 mas ~30AU (projected distance) ~6 stellar radii for a distance of ~150 pc, in agreement with our 2-dimensional radiative transfer modelling.

In addition to IRC+10216 we studied the stellar disks and the dust shells of several related objects. Angular resolutions of 24 mas at 700 nm or 57 mas 1.6 µm were achieved.