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Session 44 - Circumstellar Material.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center

[44.10] Evidence for Cometary Dust in the Disks around \beta-Pic-like stars

H. M. Butner (DTM-CIW), H. J. Walker (CLRC RAL), D. H. Wooden, F. C. Witteborn (NASA Ames)

\beta Pic is a nearby main-sequence star, which IRAS revealed to have a large infrared excess. Studies of the star have revealed that it is surrounded by an extended dusty disk. In addition, the mid-infrared spectra bear a striking similarity to the silicate emission that has been seen in some cometary spectra. We have selected a sample of main-sequence stars whose infrared properties allow us to classify them as \beta-Pic-like stars. We have undertaken a systematic study of their physical properties. In June 1994 and 1995, we obtained mid-infrared spectra (8 to 13 microns, resolution of 200) using the NASA Ames HIFOGS (High Resolution Faint Object Grating Spectrograph) at the NASA IRTF. We find a variety of silicate emission features can be seen, even in our small sample. We compare the observed spectra with a variety of mid-infrared spectra taken from different interstellar and interplanetary sources. We find the emission is most similar to the features seen arising from around young stellar objects and laboratory spectra of Interplanetary Dust Particles (IDPs). The IDP spectra also look like spectra of comets Halley and Bradfield. We discuss what implications the laboratory and comet spectra have for the possible origin and composition of the dust in the \beta-Pic-like disk systems.

Program listing for Tuesday