This is not going to be an exhaustive review of all of the literature on the subject of multiple star dynamics, although I will call your attention to the very recent review by Valtonen & Mikkola (1991) entitled “The Few-Body Problem in Astrophysics”. After all, from a dynamical point of view a multiple-star system is the physical realization of the n-body problem of celestial mechanics, and an enormous literature exists for that subject. Rather, this will be some personal thoughts on aspects of the few-body problem that are particularly relevant to the multiple-star astronomer.

One should not forget the case of n=2. Although the problem is completely solvable and contains no surprises, it is one of our reasons to exist. Especially if a binary is on a photographic program, which can yield a parallax, a total mass, and a mass-ratio, and if photometry exists, as is usually the case now for parallax stars, a real contribution is possible. Do an orbit, which is the dynamical problem, and you have two more good points for the empirical mass/luminosity relationship, which is not a bad day’s work for the astrophysicist.