The Radiative Pattern and Asymmetry of IRC +10216 at 11 μm Measured with Interferometry and Closure Phase

Abstract

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 μm 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.