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		| Paper: | 
		Formation and Evolution of Massive Stars: Current Surveys | 
	 
	
		| Volume: | 
		507, Multi-Object Spectroscopy in the Next Decade: Big Questions, Large Surveys, and Wide Fields | 
	 
	
		| Page: | 
		147 | 
	 
	
		| Authors: | 
		de Koter, A. | 
	 
	
	
		| Abstract: | 
		The advent of multi-object spectrographs on 8-10 m class telescopes has provided the opportunity to perform detailed atmospheric
 analysis of samples of several hundreds of massive stars,  prior studies being limited to several tens of objects at most.  These analyses 
 have highlighted some serious problems regarding our understanding of massive-star evolution.  A central theme in the findings is
 the prominent role of multiplicity, with the majority of high-mass stars being in close binary systems of which the components will interact 
 at some point in their lives. | 
	 
	
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