Determining Habitability: Which exoEarths should we search for life?

Abstract: Within the next few years, the first Earth-mass planets will be discovered around other stars. Some of those worlds will certainly lie within the classical "habitable zone" of their parent stars, and we will quickly move from knowing of no exoEarths to knowing many. For the first time, we will be in a position to carry out a detailed search for the first evidence of life beyond our Solar System. However, such observations will be hugely taxing and time consuming to perform, and it is almost certain that far more potentially habitable worlds will be known than it is possible to study. It is therefore important to catalogue and consider the various effects which make a promising planet more or less suitable for the development of life. In this work, we review the various planetary, dynamical and stellar influences that could influence the habitability of exoEarths. The various influences must be taken in concert when we attempt to decide where to focus our first detailed search for life. While there is no guarantee that any given planet will be inhabited, it is vitally important to ensure that we focus our time and effort on those planets most likely to yield a positive result.