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		| Paper: | Inflated Planets and their Low-Mass Companions |  
		| Volume: | 398, Extreme Solar Systems |  
		| Page: | 529 |  
		| Authors: | Mardling, R.A. |  
		| Abstract: | Various mechanisms have been proposed to explain the inflated size of HD 209458b after it became clear that it has no companions capable of producing a stellar reflex velocity greater than around 5ms−1. Had there been such a companion, the hypothesis that it forces the eccentricity of the inflated planet thereby tidally heating it may have been readily accepted. Here we summarize a paper by the author which shows that companion planets with masses as low as a fraction of an Earth mass are capable of sustaining a non-zero eccentricity in the observed planet for at least the age of the system. While such companions produce stellar reflex velocities which are fractions of a meter per second and hence are below the stellar jitter limit, they are consistent with recent theoretical work which suggests that the planet migration process often produces low-mass companions to short-period giants. |  
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