|   | 
				
					
	
		  | 
	 
	
		| Paper: | 
		Establishing Shock Diagnostics in the Pulsating Extreme Helium Star V652 Herculis | 
	 
	
		| Volume: | 
		479, Progress in Physics of the Sun and Stars | 
	 
	
		| Page: | 
		369 | 
	 
	
		| Authors: | 
		Jeffery, C. S.; Shibahashi, H.; Kurtz, D. W.; Elkin, V.; Montañés-Rodríguez,; Saio, H. | 
	 
	
	
		| Abstract: | 
		V652 Her is an extreme helium star which pulsates with a period of 0.108 d. The pulsations  are almost unique in that for 90% of the pulsation cycle the photosphere follows a near-ballistic trajectory. This is punctuated by a short acceleration phase which shows  evidence of a high Mach-number shock moving outward through the photosphere.  To explore the shock phase in more detail,  we have obtained a series of spectra at high time resolution with the high-dispersion spectrograph of the Subaru telescope.  We have also developed a theoretical framework for  coupling a hydrodynamic model of the pulsating envelope to a radiative transfer model of the photosphere. We present first results of a comparison between theoretical and observed spectra around minimum radius. | 
	 
	
		| 
			
			
		 | 
	 
	
		  | 
	 
 
					 
				 | 
				  |