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		| Paper: | 
		A Search for Star-Planet Interactions in Chromospheric Lines | 
	 
	
		| Volume: | 
		448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun | 
	 
	
		| Page: | 
		1173 | 
	 
	
		| Authors: | 
		Lenz, L. F.; Reiners, A.; Kürster, M. | 
	 
	
	
		| Abstract: | 
		Massive planets in very close orbits around their central stars can induce  so-called star-planet interactions (SPI), which may be of magnetic or gravitational nature. In both cases, SPI can potentially cause recurring chromospheric emission on the host star visible in Ca II H & K and/or Hα. The emission would be bound to the planetary orbit, not to the rotation period of the star. 
 We searched for SPI in a sample of 7 stars with massive close-in planets using high-resolution spectroscopic data taken at HRS (HET) and FEROS (La Silla). We find no periodically recurring emission in the planet-hosting stars. In the case of HD 41004 AB, a binary system consisting of a K dwarf and an M dwarf, where the M dwarf is orbited by a brown dwarf companion, we find signs of cyclic variation in the Ca II K and Hα emission lines that could be associated to interactions between the M dwarf and its companion. We present our first results of this interesting system that may become an important system for the understanding of SPI. | 
	 
	
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