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		| Paper: | 
		Ultracool Subdwarfs: Subsolar Metallicity Objects Down to Substellar Masses | 
	 
	
		| Volume: | 
		384, 14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun | 
	 
	
		| Page: | 
		126 | 
	 
	
		| Authors: | 
		Burgasser, A.J. | 
	 
	
	
		| Abstract: | 
		In the past few years, astronomers have uncovered several very low-temperature, metal-poor stars with halo or thick disk kinematics and peculiar spectral and photometric properties, so-called ultracool subdwarfs. These include the first examples of L subdwarfs - metal-poor analogs of the L dwarf spectral class - and slightly metal-deficient T dwarfs. Ultracool subdwarfs provide useful empirical tests of low temperature atmosphere and evolutionary models, and are probes of the halo mass function down to and below the (metal-dependent) hydrogen burning limit. Here I summarize the optical and near-infrared spectroscopic properties of these objects, review recent research results, and point out scientific issues of interest in this developing subject. | 
	 
	
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