Magnetohydrodynamics in Binary Stars

Magnetism in binary stars is an area of central importance in stellar astrophysics. The second edition of "Magnetohydrodynamics in Binary Stars" is a major revision of the first edition. The material has been updated and extended, including additional chapters on the origins of the stellar magnetic fields and accretion disc magnetic winds. A comprehensive account is given of the subject, from the early work up to the latest results. The unifying theme remains the redistribution of angular momentum by magnetic stresses. This occurs in a wide variety of ways, including magnetic stellar and orbital coupling, magnetic channelling of accretion streams, magnetic stellar coupling to accretion discs, dynamo field coupling in discs, and magnetic stellar and disc winds. The associated stellar spin and orbital evolution problems, including stability, are also considered. Although the main focus is on binary stars, much of the work on accretion discs and wind flows has more general astrophysical relevance. Convenient formulae are included that can be compared to observations, making the book useful to observers as well as theorists, and there are extensive reference lists. The material is mainly aimed at research workers, but parts of the text could be useful for postgraduate courses in magnetic stellar astrophysics topics.

Autorentext

Chris Campbell was formerly a Reader in Astrophysics at Newcastle University.He has published papers in leading astrophysical journals in the areas of tidal theory, stellar oscillations and a range of magnetohydrodynamics problems, particularly related to accretion processes, associated outflows and close binary stars.

Zusammenfassung
Magnetic stresses were discussed as a possible means of angular momentum transport in the development of accretion disc theory, in the late sixties and early seventies. Interest in the role of magnetic fields in close binary stars steadily increased after the discovery of the nature of AM Herculis in 1976. The observed lack of an accretion disc and the synchronous rotation of the white dwarf suggested strong magnetic effects, consistent with the high degree of optical polarization. Similar systems were soon discovered. Evidence for large magnetic fields was subsequently found in the X-ray binary pulsars and the intermediate polar binaries, both believed to include systems with partially disrupted accretion discs. A magnetically channelled wind from the main sequence secondary star has been invoked to explain the higher mass transfer rates observed in binaries above the period gap, and in an explanation of the gap. Magnetically influenced winds from accretion discs have been suggested as contributing to the inflow by removing angular momentum. Magnetism in binary stars is now an area of central importance in stellar astrophysics. Magnetic fields are believed to playa fundamental role even in apparently non-magnetic binaries. They provide the most viable means, through shear instabilities, of generating the turbulence in accretion discs necessary to drive the inflow via the resulting magnetic and viscous stresses.

Inhalt
1 Magnetism in Binary Stars.- 2 Theoretical Prerequisites.- 3 AM Herculis Stars.- 4 AM Her Stars: Inductive Magnetic Coupling.- 5 AM Her Stars: Stream Channelling and the Accretion Torque.- 6 AM Her Stars: The Maintenance of Synchronism.- 7 AM Her Stars: The Attainment of Synchronism.- 8 Binaries with Partial Accretion Discs.- 9 Disc Disruption and Accretion Curtains.- 10 Disrupted Discs: Stellar Spin Evolution.- 11 Intrinsic Magnetism in Accretion Discs.- 12 Stellar Magnetic Fields.- 13 Stellar Magnetic Winds.- 14 Accretion Disc Magnetic Winds.- Appendix.