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		| Paper: | 
		Systematics of Hot Subdwarfs Obtained from a Large Low Resolution Survey | 
	 
	
		| Volume: | 
		392, Hot Subdwarf Stars and Related Objects | 
	 
	
		| Page: | 
		75 | 
	 
	
		| Authors: | 
		Green, E.M.; Fontaine, G.; Hyde, E.A.; For, B.-Q.; Chayer, P. | 
	 
	
	
		| Abstract: | 
		We have recently completed a low resolution spectroscopic survey of several hundred subdwarf B, subdwarf O, blue horizontal branch, and post-asymptotic giant branch stars. Homogeneous effective temperatures, surface gravities and helium abundances were derived by fitting Balmer and helium lines using a large grid of NLTE zero-metallicity atmospheres. The survey is complete for known hot subdwarf candidates in the northern hemisphere brighter than about 14.2. We used the same spectra to derive multiple radial velocities for a large fraction of the hot subdwarfs, in order to investigate patterns of radial velocity variability in the surface gravity – effective temperature plane, and also in the V −J vs. J−H diagram. We present several examples illustrating how the binary characteristics of hot subdwarfs, as functions of temperature, gravity and color, can be used to set important constraints on their formation and evolution. | 
	 
	
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