Wide binaries from few-body interactions (Q1390804)

The importance of the few body process in disruption of small star clusters was first demonstrated by \textit{S. von Hoerner} [Z. Astrophys. 50, 184-214 (1960; Zbl 0093.23604)). The rapid binary formation and subsequent ejection from star clusters was confirmed later by many authors. The binaries may form in a cluster of initially ''single'' stars, of a certain fraction of stars may be binaries as a result of the star formation process. In either case the three and four body interactions play an important role. In this article the known finnish scientist presents a review both his own results and the results of other investigators. Particularly, the review of the orbital parameters which are expected from the few-body process is presented. First, the solutions of the general three-body problem are described, and then a detailed discussion of the theory relevant to binaries follows. Among other things, Opik's law of the distribution of semi-major axes of the binaries is derived. And finally, recent results from the few-body problem of extended bodies which may be relevant to the early dynamical evolution of protostellar clauds, are summarized.