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J.E. Chambers (NASA Ames Research Center)
N-body simulations of terrestrial planet formation have been quite successful in producing planetary systems resembling the inner planets of the Solar System. To date, these simulations have either neglected the presence of giant planets, or incorporated giant planets similar to Jupiter and Saturn. However, the giant planets known to orbit other stars are very different from those in the Solar System. Typically, they have shorter periods and more eccentric orbits than Jupiter and Saturn, and in many cases they are also more massive than these planets.
Here I present new N-body simulations of terrestrial planet formation in the presence of a variety of giant planet configurations. These include both some observed systems, and variations on the Jupiter-Saturn system. The new simulations show that Earth-like planets could readily have formed if Jupiter's orbit was at 3 AU, if Jupiter was 3 times more massive, or if both Jupiter and Saturn were 3 times more massive. Conversely, terrestrial planet formation would have been severely retarded in the presence of a giant planet moving on an eccentric orbit, especially if two giants with eccentric orbits were present. In these cases, large parts of the terrestrial region are rendered unstable due to resonances with the giant planets.
The short periods and eccentric orbits of the giant planets orbitting 47 UMa, 14 Her and Epsilon Eri would also have hampered the formation of habitable planets in these systems. However, in the first two cases, terrestrial planets may have formed near the inner edge of the stars' habitable zones.