Because of the high eccentricities ( \sim 0.3 ) of two of the possible planets about the star Upsilon Andromeda , the stability of the system requires careful study .
We present results of 1000 numerical simulations which explore the orbital parameter space as constrained by the observations .
The orbital parameters of each planet are chosen from a Gaussian error distribution , and the resulting configuration is integrated for 1,000,000 years .
We find that 84 % of these integrations are stable .
Configurations in which the eccentricity of the third planet is \lesssim 0.3 are always stable , but when the eccentricity is \gtrsim 0.45 the system is always unstable , typically producing a close encounter between the second and third planets .
A similar exercise with the gas giants in our own Solar System sampled with the same error distribution was performed .
Approximately 81 % of these simulations were stable for 10 ^ { 6 } years . \keywords celestial mechanics , stellar dynamics , planetary systems , methods : n-body simulations , stars : individual ( \upsilon Andromedae )