36th DPS Meeting, 8-12 November 2004
Session 35 Extrasolar Planets
Poster II, Thursday, November 11, 2004, 4:15-7:00pm, Exhibition Hall 1A

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[35.06] Stability and Secular Resonance in the \upsilon Andromedae Planetary System

V. J. Lystad (Northwestern University), E. B. Ford, D. A. Fischer (University of California, Berkeley), F. A. Rasio (Northwestern University)

Since the announcement of the triple planet system orbiting upsilon Andromedae by Butler et al. in 1999 the best-fit orbital parameters of the system have varied significantly with additional observations over the years. Using the most current radial velocity data, we have generated initial conditions by sampling from posterior distribution of the orbital parameters, including orbital periods, eccentricities, masses, and inclinations. We have performed thousands of numerical integrations in order to investigate the stability and dynamics of the system. All of our integrations run for a minimum of 106 years, unless the system becomes unstable earlier, as indicated by the occurrence of a close encounter between two planets or the collision of one planet with the central star. Based on these numerical results we find that, for the coplanar case, at inclinations below about 40\circ more than half of the systems integrated were unstable, suggesting that the masses of the planets are unlikely to be greater than twice their minimum values. Further, while secular resonance between the middle and outer planets does occur for some orbital configurations, the planets exhibit no such resonance in the majority of stable systems.

Work supported by the NSF.

The author(s) of this abstract have provided an email address for comments about the abstract: vela@northwestern.edu

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.