  Prior work has found that a variety of terrestrial planetary compositions are
expected to occur within known extrasolar planetary systems. However, such
studies ignored the effects of giant planet migration, which is thought to be
very common in extra-solar systems. Here we present calculations of the
compositions of terrestrial planets that formed in dynamical simulations
incorporating varying degrees of giant planet migration. We used chemical
equilibrium models of the solid material present in the disks of five known
planetary host stars: the Sun, GJ 777, HD4203, HD19994 and HD213240. Giant
planet migration has a strong effect on the compositions of simulated
terrestrial planets as the migration results large-scale mixing between
terrestrial planet building blocks that condensed at a range of temperatures.
This mixing acts to 1) increase the typical abundance of Mg-rich silicates in
the terrestrial planets feeding zones and thus increase the frequency of
planets with Earth-like compositions compared with simulations with static
giant planet orbits; and 2) drastically increase the efficiency of the delivery
of hydrous phases (water and serpentine) to terrestrial planets and thus
produce water worlds and/or wet Earths. Our results demonstrate that although a
wide variety of terrestrial planet compositions can still be produced, planets
with Earth-like compositions should be common within extrasolar planetary
systems.
