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		| Paper: | 
		Analyses of IRAS low resolution spectra of young planetary nebulae | 
	 
	
		| Volume: | 
		9, Cool Stars, Stellar Systems, and the Sun: Sixth Cambridge Workshop | 
	 
	
		| Page: | 
		471 | 
	 
	
		| Authors: | 
		Zhang, Cheng-Yue; Kwok, Sun | 
	 
	
	
		| Abstract: | 
		The 18-micron silicate feature is detected in 11 young planetary nebulae (PNe) selected from the radio properties. The presence of the 18-micron silicate feature suggests that the oxygen-rich PNe are more common than previously believed. The silicate dust probably originates from the remnants of the circumstellar envelopes of the nebulae's asymptotic giant-branch progenitors. Most interestingly, their six young PNe show both oxygen- and carbon-rich dust features. | 
	 
	
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