The radiative pattern and asymmetry of IRC+10216 at 11 μm measured with interferometry and closure phase

The unusual source IRC + 10216 is the brightest stellar object at mid-infrared wavelengths in the northern hemisphere. Adding to its distinctiveness, the dust around IRC + 10216 almost completely enshrouds the star and has an extremely complex distribution. We report the imaging of IRC + 10216 at 11.15 mu m with three telescopes and the closure phase at two different stellar phases. Three-baseline interferometry data from a linear array of telescopes is used to create a one-dimensional image of the star and circumstellar dust. The two epochs over which data have been taken provide information at different position angles, which yields some insight into the two-dimensional structure of IRC + 10216. Specifically, we observe two areas of peaked intensity. The first is 66 +/- 4 mas to the west and 160 +/- 51 mas to the south of the star, and the second is 227 +/- 8 mas to the east and 94 +/- 57 mas to the south. These two features can explain most of the observed asymmetry.