Dynamics and Stability of Triple Stars 

SEPPO MIKKOLA
Tuorla Observatory,University of Turku, 21500 Piikkioe, Finland.

Evolution of (point-mass) three-body systems is known to be 
qualitatively similar in future and past: 
the system disrupts (unstable) ejecting one of the stars,
in both direction of time, or it stays bounded (stable) forever. 
Consequently any encounter of a binary and a single star, 
however complicated, eventually
leads to ejection of one of the stars leaving behind a binary.
The most common stable triple systems are the hierarchical ones.
Among these is the interesting case of high mutual 
inclination with strong eccentricity variation (Kozai-resonance).
Other bounded triples include: the `figure of 8' stable (quasi-)periodic system,
some (nearly) rectilinear orbits and co-orbital solutions.

We discuss the dynamics of triple systems and present fast 
reliable numerical methods for computing the motions.