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G. C. Sloan (Cornell, Boston College), J. H. Goebel (NASA/Ames), K. E. Kraemer (Boston Univ., Air Force Research Lab.), S. D. Price (Air Force Research Lab.)
We present initial results of an on-going analysis of the spectra from 160 oxygen-rich dust shells observed by the Short Wavelength Spectrometer (SWS) on the {\em Infrared Space Observatory}. The strength of the dust emission feature at 13~\mum correlates with the strength of another dust feature centered ~19.5~\mum. These features occasionally appear superimposed on the broader emission features from amorphous silicates at 10 and 18~\mum, but they appear more often in spectra showing lower-contrast dust emission from amorphous alumina or in some cases from spectra showing little or no other dust emission. Comparison of the spectra with laboratory data of crystalline alumina (\alpha--Al2O3), which show emission features at 13 and 21~\mum, would strengthen the case for crystalline alumina as the carrier of the 13~\mum feature if the shift from 21 to 19.5~\mum could be explained. We also investigate several additional spectral features. These include the possible emission feature at 7~\mum, possible narrow dust features at 12 and 18~\mum which may be related to the 13~\mum feature, the CO2 emission bands (at 13.9, 14.9, and 16.2~\mum), and the atmospheric absorption bands from CO, SiO, and other molecules in the 2--10~\mum spectal region.
The author(s) of this abstract have provided an email address for comments about the abstract: sloan@ssa1.arc.nasa.gov