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**Session 44 - Double Stars.**

*Display session, Thursday, January 08*

*Exhibit Hall, *

## [44.16] Dynamics of Extrasolar Planets

*F. A. Rasio, E. B. Ford, B. Kozinsky (MIT)*
We present a summary of the dynamics of hierarchical triple systems
with the application to planetary systems in mind. Using secular
perturbation theory, we explore two limiting cases of the inclination
analytically. In the limit of large ratio of semi-major axes and high
relative inclinations, the induced variations can be calculated
analytically. Additionally, we present analytical results in the
limit of large ratio of semi-major axes, low inclination, and low
eccentricity. Numerical simulations are presented to both verify the
analytical work and examine how well the analytical approximations
hold as the ratio of semi-major axes, inclinations, and eccentricities
are varied. Finally, we apply these results to some recently detected
planetary systems. The 16 Cygni System is a wide binary in which one
of the two stars, 16 Cygni B, has a giant planet of mass 1.5 / \sin i
Jupiter masses in an eccentric orbit of a = 1.6 AU and e = 0.63.
For high relative inclinations between the two orbits the high
eccentricity can be attributed to the secular perturbation of 16 Cygni
A. The PSR B1620-26 in M4 contains a giant planet or brown dwarf in a
wide orbit around an inner binary pulsar with e = 0.0253. For some
orbital solutions, this eccentricity could be attributed to the
secular perturbations of the outer giant planet or brown dwarf.

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

**Program
listing for Thursday**