| |
| | Piet Hut: Two-Body Problem: Double Stars |
 | | Especially when the shapes of the bodies are influenced by their relative motion, as is the case with tidal interactions between stars or planets or moons, the resultant perturbed two-body problem has to be solved either numerically, or analytically through a perturbation analysis. |
 | | The solution to the gravitational two-body problem in Newtonian dynamics was provided by Newton himself: the relative motion of the two bodies forms a conic section, a circle, ellipse, parabola, or hyperbola. |
 | | Intuitively, it is clear that a double star configuration forms a stable equilibrium when the two stars are co-planar, synchronized (where their spin axes align with the orbital angular momentum, and the spin periods equal the orbital period), and they are in a circular orbit. |
| www.ids.ias.edu /~piet/act/astro/two (895 words) |
|