Habitability of known exoplanetary systems

Masses are likely to be within a factor of a few of the Earth's mass. Currently, we do not have sufficiently sensitive techniques to detect Earth-mass planets, except in rare circumstances.

It is thus necessary to model the known exoplanetary systems. In particular, we need to establish whether Earth-mass planets could be present in the classical habitable zone (HZ) or whether the giant planets that we know to be present would have gravitationally ejected Earth-mass planets or prevented their formation. We have answered this question by applying computer models to the 152 exoplanetary systems known by 2006 April 18 that are sufficiently well characterized for our analysis.