1998A&A...334L...5H

We present new diffraction-limited interferometric images of the carbon star IRC+10216 at wavelengths of 2.2µm and 3.4µm. These show that the distribution of the near-infrared emission from the star departs significantly from a spherical geometry on 0.1 arcsecond scales. At 3.4µm, i.e. close to the peak of the star/dust-shell spectral energy distribution, approximately 60% of the flux comes from regions asymmetrically disposed about the stellar photosphere at radii of 0.1-0.3 arcseconds. Images taken in 1989 and 1997 show large changes in the distribution of flux, but a consistent axis of symmetry at a PA of approximately -5°. Archival Hubble Space Telescope images at 0.79 and 1.06µm show filaments with the same symmetry axis and a dark lane perpendicular to this axis approximately 0.25 arcseconds to the north of the star. Taken together, these data suggest a model in which the asymmetries seen are a consequence of envelope clearing along a bipolar axis. These observations indicate that the asymmetries seen in planetary nebulae may already be established before the progenitor star has left the AGB.