SPATIALLY-RESOLVED MIDINFRARED OBSERVATIONS OF CIRCUMSTELLAR DUST AROUND AB AURIGAE

The Herbig Ae star, AB Aur, was observed at wavelengths of 11.7 and 17 .9 mu m using the Cornell SpectroCam-10 imaging spectrometer on the 5 m Hale Telescope. The observed images were deconvolved using a Bayesia n estimator which provided superresolution from the incorporation of p rior information (the positivity of intensity and the finite support o f the emission); this yielded an angular resolution of similar to 0.'' 2, which subtends similar to 30 AU at a distance of 160 pc. Our decon volved images have resolved the source at both wavelengths and show so urce diameters of approximately 40 and 80 AU at 11.7 and 17.9 mu m, re spectively. At 11.7 mu m, the source exhibits some complex structure w hich has been confirmed using observations on two separate observing r uns and different observing techniques; one characteristic of this str ucture is the presence of a central depression. The source appearance is markedly different at 17.9 mu m and is characterized by a central c omponent which is flanked by a pair of weaker, diametrically opposed f eatures suggestive of an edge-on disk. We hypothesize that such a disk surrounds a tenuous, roughly spherical cloud which produces the silic ate emission feature and which dominates the 11.7 mu m emission.