The first study of migration-induced resonances in a pair of
Earth-like planets has been performed by Papaloizou & 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 & 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 planets 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.