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		| Paper: | 
		A Key Science of the Starburst Open Cluster Westerlund 1: The Initial Mass Function | 
	 
	
		| Volume: | 
		482, 10th Pacific Rim Conference on Stellar Astrophysics | 
	 
	
		| Page: | 
		225 | 
	 
	
		| Authors: | 
		Lim, B.; Sung, H.; Hur, H. | 
	 
	
	
		| Abstract: | 
		The initial mass function (IMF) is an important tool to understand the star formation processes 
 and chemical evolution of distant galaxies as well as our Galaxy. While the IMF of the intermediate- 
 to low-mass stars is relatively well studied, that of the most massive stars (>15M☉) is 
 poorly known due to the paucity of such stars in the Solar neighborhood. The starburst 
 open cluster Westerlund 1 known as the most massive open cluster in the Galaxy 
 is an ideal laboratory to study the IMF of the high-mass part owing to the vast number of 
 massive stars. In this study we present the IMF of the cluster derived from both optical and 
 near infrared photometry. The slope of the IMF appears to be shallow (Γ =–0.8 ±0.1) 
 for masses larger than 5 M☉. Here, we will present a discussion on the shape of the IMFs 
 for three starburst open clusters including NGC 3603 and the Arches cluster. | 
	 
	
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