Mid-Infrared Imaging of Alpha Orionis

We have imaged the M2Iab supergiant star Alpha Ori at 11.7 micron and 17.9 micron using the Hale 5-m telescope and an array camera with sub-arcsecond angular resolution. Our images reveal the circumstellar dust shell extending out to approximately 5" from the star. By fitting two multi-parameter models to the data, we find values for the dust shell inner radius, the temperature at this radius, the percentage flux produced by the circumstellar material at each of our wavelengths, and the radial dependence of the dust mass density. We present profiles of the mean surface brightness as a function of radius and the power detected from within annular rings as a function of radius.