Mid-infrared images of the circumstellar dust around α Scorpii

We present the first two-dimensional mid-infrared images of the circumstellar dust distribution around the supergiant star alpha Scorpii. Our observations were made at wavelengths of 12.5 and 20.8 mum using the MIRLIN focal-plane array camera on the Keck II 10 m telescope, with spatial resolution (lambda /D) of 0.29 and 0.48 at the two wavelengths, respectively. Our deconvolved images, which provide a resolution enhancement of approximately a factor of 2, show that the dust shell previously detected in one-dimensional scans is actually highly nonuniform. Specifically, the shell is now seen to be concentrated largely into three discrete clumps, and there is evidence of a more recent ejection which has left a central concentration of dust within about 0.3 from the star.