DETECTION OF SILICATES IN THE BETA-PICTORIS DISK

We have detected a broad 10-mu-m emission feature within 3" of the star beta Pic which is known to have a circumstellar, possibly protoplanetary, disk. The observations were made using four narrow-band filters (DELTA-lambda approximately-equal-to 1-mu-m) in the MSFC bolometer array at the IRTF. The emission feature closely resembles silicate features observed in comets Halley and Kohoutek and in a variety of Galactic sources. The feature is strong, with the total flux density emitted by dust at 10.3-mu-m being at least twice the estimated continuum at that wavelength, and must be emitted by particles with characteristic radii less than 10-mu-m.