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P. Artymowicz (Stockholm Observatory)
Upsilon Andromedae, the first multiplanetary system discovered among the main-sequence stars, is much more dynamically stable than the first investigations suggested. Direct N-body simulations, treating the inner, short-period planet in a simplified manner, suggest that the system survived in the current state since the epoch of formation ~3 Gyr ago. Orbital eccentricities of the three planets are almost linearly correlated with planetary masses, which is very unlikely to have resulted from standard 4-body interaction (or planet-planet interaction alone). We discuss the possibility that the system's orbits were shaped by the interaction of protoplanets with the protoplanetary disk, in the first few millions of ups And's existence.