  Context: The principle definition of habitability for exoplanets is whether
they can sustain liquid water on their surfaces, i.e. that they orbit within
the habitable zone. However, the planet's magnetosphere should also be
considered, since without it, an exoplanet's atmosphere may be eroded away by
stellar winds. Aims: The aim of this paper is to investigate magnetospheric
protection of a planet from the effects of stellar winds from solar-mass stars.
Methods: We study hypothetical Earth-like exoplanets orbiting in the host
star's habitable zone for a sample of 124 solar-mass stars. These are targets
that have been observed by the Bcool collaboration. Using two wind models, we
calculate the magnetospheric extent of each exoplanet. These wind models are
computationally inexpensive and allow the community to quickly estimate the
magnetospheric size of magnetised Earth-analogues orbiting cool stars. Results:
Most of the simulated planets in our sample can maintain a magnetosphere of ~5
Earth radii or larger. This suggests that magnetised Earth analogues in the
habitable zones of solar analogues are able to protect their atmospheres and is
in contrast to planets around young active M dwarfs. In general, we find that
Earth-analogues around solar-type stars, of age 1.5 Gyr or older, can maintain
at least a Paleoarchean Earth sized magnetosphere. Our results indicate that
planets around 0.6 - 0.8 solar-mass stars on the low activity side of the
Vaughan-Preston gap are the optimum observing targets for habitable Earth
analogues.
