Abstract
We have obtained high spatial resolution mid-IR observations of four intermediate-mass pre–main-sequence stars: HD 259431, AS 310, LkHα 234, and MWC 1080. Our observations reveal the morphology of the circumstellar (500–10,000 AU) environments of these young stars. We resolve companion stars and complex diffuse emission from dust that can account for on average 50% of the IR emission detected in previous low-resolution observations. We calculate new spectral indices for these objects and show that they differ from those expected from simple geometrically flat disk models. We also show mid-IR spectral energy distributions that reveal the presence of silicate emission and absorption features for several objects. Finally, temperature maps constructed from our observations suggest the presence of transiently heated grains, and optical depth maps point to the locations of the most embedded objects.
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