  We present estimations of dipolar magnetic moments for terrestrial exoplanets
using the Olson & Christiansen (2006) scaling law and assuming their interior
structure is similar to Earth. We find that the dipolar moment of fast rotating
planets (where the Coriolis force dominates convection in the core), may amount
up to ~80 times the magnetic moment of Earth, M_Earth, for at least part of the
planets' lifetime. For very slow rotating planets (where the force of inertia
dominates), the dipolar magnetic moment only reaches up to ~1.5 M_Earth.
Applying our calculations to currently confirmed rocky exoplanets, we find that
CoRoT-7b, Kepler-10b and 55 Cnc e can sustain dynamos up to ~ 18, 15 and 13
M_Earth, respectively. Our results also indicate that the magnetic moment of
rocky exoplanets not only depends on their rotation rate, but also on their
formation history, thermal state, age and composition, as well as the geometry
of the field. These results apply to all rocky planets, but have important
implications for the particular case of exoplanets in the Habitable Zone of
M-dwarfs.
