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		| Paper: | 
		Crystalline Silicates, Comets, and Protoplanetary Disk Evolution | 
	 
	
		| Volume: | 
		196, Thermal Emission Spectroscopy and Analysis of Dust, Disks, and Regoliths | 
	 
	
		| Page: | 
		99 | 
	 
	
		| Authors: | 
		Wooden, Diane H.; Harker, David E.; Woodward, Charles E. | 
	 
	
	
		| Abstract: | 
		The analysis of the silicate mineralogy of comets, pre-main sequence T Tauri stars and Herbig Ae/Be stars, and main sequence β-Pic systems probes chemical and physical conditions in potentially planet-forming environments, condensation of dust from the gas-disk, accretion and annealing of interstellar amorphous silicates, and aggregation and accretion of these solids into planetesimals and comets. Ground-based and space-borne ISO spectroscopy of the 10 micron and 20 micron silicate resonances at medium to high resolution (R~= 200-1000) combined with analytical modeling efforts permits the testing of a current (Waelkens et al. 1999; Nuth 1999) yet unproved (van den Ancker et al. 1999) hypothesis that the degree of silicate crystallinity increases with age and disk evolutionary state. Correlating silicate mineralogy (including Mg-content and degree of crystallinity versus amorphousness) with age, disk properties, and circumstellar environment, develops the relationship between grain properties and protoplanetary disk evolution. | 
	 
	
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