Book contents
- Frontmatter
- Contents
- Preface
- Introduction
- Part I Idealized homogeneous systems – basic ideas and gentle relaxation
- Part II Infinite inhomogeneous systems – galaxy clustering
- Part III Finite spherical systems – clusters of galaxies, galactic nuclei, globular clusters
- 37 Breakaway
- 38 Violent relaxation
- 39 Symmetry and Jeans' theorem
- 40 Quasi-equilibrium models
- 41 Applying the virial theorem
- 42 Observed dynamical properties of clusters
- 43 Gravithermal instabilities
- 44 Self-similar transport
- 45 Evaporation and escape
- 46 Mass segregation and equipartition
- 47 Orbit segregation
- 48 Binary formation and cluster evolution
- 49 Slingshot
- 50 Role of a central singularity
- 51 Role of a distributed background
- 52 Physical stellar collisions
- 53 More star–gas interactions
- 54 Problems and extensions
- 55 Bibliography
- Part IV Finite flattened systems – galaxies
- Index
48 - Binary formation and cluster evolution
Published online by Cambridge University Press: 05 July 2011
- Frontmatter
- Contents
- Preface
- Introduction
- Part I Idealized homogeneous systems – basic ideas and gentle relaxation
- Part II Infinite inhomogeneous systems – galaxy clustering
- Part III Finite spherical systems – clusters of galaxies, galactic nuclei, globular clusters
- 37 Breakaway
- 38 Violent relaxation
- 39 Symmetry and Jeans' theorem
- 40 Quasi-equilibrium models
- 41 Applying the virial theorem
- 42 Observed dynamical properties of clusters
- 43 Gravithermal instabilities
- 44 Self-similar transport
- 45 Evaporation and escape
- 46 Mass segregation and equipartition
- 47 Orbit segregation
- 48 Binary formation and cluster evolution
- 49 Slingshot
- 50 Role of a central singularity
- 51 Role of a distributed background
- 52 Physical stellar collisions
- 53 More star–gas interactions
- 54 Problems and extensions
- 55 Bibliography
- Part IV Finite flattened systems – galaxies
- Index
Summary
Binaries in clusters act as energy sources and sinks. As sinks of gravitational potential energy, they can absorb more than one-half the total binding energy of a cluster. As corresponding sources of kinetic energy they heat the cluster.
How fast will binaries form? How important can they be? An analytic theory of these processes, even in the approximations for which it is available, is quite complex. N-body simulations are sometimes the only way to answer detailed questions, especially for a broad spectrum of masses. Nevertheless, many useful results are available, and this section describes some. Following discussions of how binaries form by interactions of single stars, we consider how they can affect a cluster's evolution. From a more general point of view, these can be regarded as examples of energy transfer between different levels of hierarchial structure in a cluster.
Formation by few-body interactions
Binaries may be born directly when stars or galaxies form. We do not really understand how this occurs, so all we can do is add such initial binaries into the cluster in an ad hoc way, and then examine their development. Even if there are no initial binaries, however, the fluctuating gravitational field may chance to bring a few stars so close together, with such low relative velocities, that they remain temporarily bound. Usually these subclusters lead a fleeting existence, for later fluctuations may inject enough kinetic energy to make them decay.
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- Information
- Gravitational Physics of Stellar and Galactic Systems , pp. 352 - 364Publisher: Cambridge University PressPrint publication year: 1985