  The first study of migration-induced resonances in a pair of Earth-like
planets has been performed by Papaloizou and Szuszkiewicz (2005). They
concluded that in the case of disparate masses embedded in a disc with the
surface density expected for a minimum mass solar nebula at 5.2 au, the most
likely resonances are ratios of large integers, such as 8:7. For equal masses,
planets tend to enter into the 2:1 or 3:2 resonance. In Papaloizou and
Szuszkiewicz (2005) the two low-mass planets have masses equal to 4 Earth
masses, chosen to mimic the very well known example of two pulsar planets which
are close to the 3:2 resonance. That study has stimulated quite a few
interesting questions. One of them is considered here, namely how the behaviour
of the plan- ets close to the mean-motion resonance depends on the actual
values of the masses of the planets. We have chosen a 3:2 commensurability and
investigated the outcome of an orbital migration in the vicinity of this
resonance in the case of a pair of equal mass super-Earths, whose mass is
either 5 or 8 Earth masses.
