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E.V. Quintana (NASA Ames, University of Michigan), J.J. Lissauer (NASA Ames), E.J. Rivera (NASA Ames, SUNY Stony Brook), M.J. Duncan (Queen's University)
If a planetary-mass body were present in the asteroid belt, the orbits of the terrestrial planets and those of the giant planets would be more closely coupled. A greater exchange in angular momentum could affect the stability of the terrestrial planets. To study this effect, we have simulated several systems consisting of the Solar System planets and a 0.1 - 10 Earth mass object on the orbit of a main belt asteroid. An integration with Ceres at 5 Earth masses remained stable for a billion years. Ceres at 10 Earth masses, however, caused the system to become unstable at ~ 25 - 50 million years. When additional mass was given to both Ceres (bringing it up to 5 Earth masses) and Mars (1 Earth mass), the systems self-destructed within ~ 40 million years. Systems with Pallas at 5 Earth masses became unstable at 150 - 170 million years. Vesta at 5 Earth masses caused the system to become unstable in as little as 13 million years, but systems with Vesta at 2 Earth masses remained stable for 100 million years.