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Session 47 - Circumstellar Disks & Shells.
Display session, Thursday, January 08
Exhibit Hall,

[47.05] Near-Infrared Spectra of the \beta Pictoris Disk

S. B. Fajardo-Acosta (U. of Denver), D. E. Backman (Franklin and Marshall College), F. C. Witteborn (NASA Ames)

Since the discovery of its extended infrared-emitting disk, \beta Pictoris has been considered to be a likely candidate for a planet-forming system. The size and mineralogy of the particles comprising the disk provide clues that could distinguish interplanetary debris from interstellar dust and grains forming from photospheric ejecta. In an effort to characterize such debris we obtained infrared spectra (0.94 to 2.4 \mum) of the \beta Pictoris disk using an imaging spectrometer on the 4-m telescope at Cerro Tololo. Spectra were obtained of the portion of the disk outwards of 65 AU from the central star by offsetting the star outside the spectrometer slit. The contribution to the spectrum from telescope and atmospheric scattering was removed by subtraction of an appropriately scaled spectrum of a similarly offset \alpha Pictoris. The resulting spectra are devoid of ice features, but are quite similar to some comet spectra. The general continuum is red compared to \beta Pictoris suggesting particle sizes larger than a few microns. These characteristics are consistent with the presence of collision fragments of rocky planetesimals or the dusty component of comets.

Program listing for Thursday