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		| Paper: | 
		Betelgeuse: A Case Study of an Inhomogeneous Extended Atmosphere | 
	 
	
		| Volume: | 
		425, Hot and Cool: Bridging Gaps in Massive Star Evolution | 
	 
	
		| Page: | 
		152 | 
	 
	
		| Authors: | 
		Harper, G. M. | 
	 
	
	
		| Abstract: | 
		Despite being one of the best-studied stars, the massive M supergi\-ant Betelgeuse had us fooled. An unfortunate convergence of observational interpretation, semi-empirical analyses, and theoretical modeling led to the notion that the accelerating wind was at chromospheric temperatures. Only with high spatial-resolution multi-wavelength datasets covering ultraviolet and centimeter radio wavelengths did it finally become apparent that the bulk of the wind is actually much cooler, while encompassing tiny volumes of hot ultraviolet-emitting plasma. High spectral-resolution TEXES observations of mid-IR [Fe II] emission are now revealing the dynamical nature of the pervasive cool plasma. Extended and inhomogeneous atmospheres appear to be a common property of the early M supergiants, making Betelgeuse an important case study. | 
	 
	
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