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M.L. Sitko (University of Cincinnati), D.K. Lynch, R.W. Russell (Aerospace Corporation), C.A. Grady (NOAO/STIS)
Spectroscopic observation between 3-14 microns of 3 stars in the TW Hya Association were obtained using the Aerospace Corporation Broadband Array Spectrometer System (BASS) on the NASA IRTF telescope. The targets observed were TW Hya, HR 4796, and HD 98800. Both of the late-type stars, TW Hya and HD 98800, exhibit a strong 10 micron silicate emission band. The strong emission indicates the presence of small dust grains close to the star, at angular distances not currently accessible to coronagraphic techniques. The spectral structure due to crystalline material that is present in some young early-type stars (HD 163296, HD 31648, etc.) is not apparent in these two objects. For HR 4796, the dust emission is weak, but detectable above the expected photospheric emission in the 10 micron band. The data are unfortunately of insufficient quality for any detailed mineralogical analysis.
This work was supported by the URC and Physics Department of the University of Cincinnati (MLS), the Aerospace Corporation IRD program (DKL and RWR), and the NOAO/STIS project (CAG).