  Most observed extrasolar planets have masses similar to, but orbits very
different from, the gas giants of our solar system. Many are much closer to
their parent stars than would have been expected and their orbits are often
rather eccentric. We show that some of these planets might have formed in
systems much like our solar system, i.e. in systems where the gas giants were
originally on orbits with a semi-major axis of several au, but where the masses
of the gas giants were all rather similar. If such a system is perturbed by
another star, strong planet-planet interactions follow, causing the ejection of
several planets while leaving those remaining on much tighter and more
eccentric orbits. The eccentricity distribution of these perturbed systems is
very similar to that of the observed extrasolar planets with semi-major axis
between 1 and 6 au.
