Extending the Definition of Planet Habitability to Include Space Environment Factors

The search for habitable Earth-size exoplanets, or "Earth-twins" has led to the discovery of number of candidates. Most of these candidates have been found in the Habitable Zone (HZ) of M-dwarf stars, due to the observational constrain that only short-period small planets can be detected with our current instruments. Despite of the fact that the equilibrium temperature of these planets make them habitable, space environment factors at these short-period orbits might significantly affect the chances of these planets to be habitable. I will discuss what are these space environment factors and their potential impact on habitability.