Origin and Evolution of Binary Systems

Abstract

As is well known, the evolution of the stars constitutes a process which (barring exceptional stages) proceeds at so slow a pace that no changes arising from it become perceptible on the human time scale. However, atomic and nuclear processes which motivate such an evolution are now sufficiently well understood to enable us to predict the past and the future of self-gravitating configurations of stellar mass and size with a fair probability throughout most (though not yet all) parts of their lives. In particular, it is generally recognized now that the evolution of the stars constitutes — in effect — an initial-value problem, the course of which is governed by the star’s initial mass, chemical composition, and (to a lesser extent) angular momentum. Of these the mass and momentum are known to remain unaltered for long evolutionary epochs; while the mean composition changes continuously and irreversibly in the course of time as a result of gradual depletion of hydrogen and other kinds of nuclear fuel in the interiors of the stars.

“The study of Algol variables should bring us to the very threshold of the question of stellar evolution, and to the heart of not a few greatest cosmical problems.”

A. W. Roberts (1902)