Suitable StarsMost stars in the Galaxy have at least one stellar companion---binary or multiple star systems. Stars like our Sun with no stellar companion are in the minority. It would probably be difficult for there to be stable, only slightly elliptical planet orbits in a binary or multiple star system. Complex life (multi-cellular) will need to have a stable temperature regime to form so the planet orbit cannot be too eccentric. Simple life like bacteria might be able to withstand large temperature changes on a planet with a significantly elliptical orbit but complex life is the much more interesting case. Suitable binary stars would be those systems where either the binary stars orbit very close to each other with the planet(s) orbiting both of them at a large distance or the binary stars orbit very far from each other so the planet(s) could reside in stable orbits near each of the stars---the one star's gravity acting on a planet would be much stronger than that of the other star. The
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