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Paper: Simulation of 10μm Astronomical Spectra with Mixtures of Crystalline and Amorphous Silicates
Volume: 196, Thermal Emission Spectroscopy and Analysis of Dust, Disks, and Regoliths
Page: 31
Authors: Bowey, J. E.; Adamson, A. J.; Speck, A. K.
Abstract: Since the published 10μm spectra of crystalline minerals vary, and data produced by the KBr pellet method may be shifted in wavelength by up to 0.3μm (Dorschner et al. 1978), we compare published 10μm silicate absorption spectra from seven publications. Mineralogical effects were deduced by comparing data for several members of a mineral group and by studying the effect of laboratory processes on the spectra of individual minerals. Wavelength shifts of up to ~ 0.5μm can be introduced by real mineralogical differences between specimens i.e. (i) variations in the relative proportions of metal ions and (ii) differences in crystalline structure. If the KBr matrix shift exists, in these data it is insignificant and <= 0.05μm. Circumstellar, diffuse medium and molecular cloud and YSO 10μm profiles are interpreted in terms of a mixed crystalline and amorphous silicate mineralogy since ISO 20-45μm observations reveal the presence of crystalline silicates in circumstellar dust. The wavelength of the peak (λpk) and full-width-half maximum (FWHM) of astronomical 10μm profiles can be reproduced by mixtures of crystalline and amorphous silicates. The increased width of molecular cloud profiles can be simulated by increasing the proportion of crystalline pyroxene.
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