摘要:

A simple kinematic model has been applied to simulate the evolution of the interstellar magnetic field permanently twisted by turbulent gas motions accompanied by effects of the field diffusion. The magnetic field was found to develop well-ordered twisted structures over the whole gas parcel analyzed. This field configuration has a preferred sense of twisting dependent on the helicity of the gas flow. The model of synchrotron emission and polarization of M31-like galaxy containing magnetic field structures taken from our simulations reproduces quite well its basic observed radio and polarization properties.

ISSN:0309-1929    

DOI:10.1080/03091929208229057

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Criteria for the stability of an axisymmetric, compressible, differentially rotating, non self-gravitating fluid with a purely poloidal magnetic field are derived from a global analysis using an effective variational principle. These are applied to the example of geometrically thin accretion discs in which it has been recently suggested that unstable axisymmetric modes could be important in leading to angular momentum transport thus providing an effective viscosity. In the case of an externally imposed magnetic field it is possible to estimate the strength of the field above which the disc will become stable to this sort of mode. To give such an estimate, a global analysis of the type given here is necessary. The estimated field strength was found to be such that the typical Alfven speed is proportional to the product of the orbital velocity and the square root of the ratio of the disc thickness to radius.

ISSN:0309-1929    

DOI:10.1080/03091929208229058

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The angular momentum exchange between a binary magnetic neutron star and its accretion disc is considered. In a previous paper it was shown that if the disc's magnetic diffusivity,η, is due to buoyancy or turbulence, disruption occurs where the magnetic extraction of angular momentum starts to dominate that due to viscous advection. The disruption radius is significantly larger than one half the spherical Alfvén radius, often previously used for the disc's inner edge.

ISSN:0309-1929    

DOI:10.1080/03091929208229059

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

PLASMA LOOPS IN THE SOLAR CORONA, by R. J. Bray, L. E. Cram, C. J. Durrant and R. E. Loughhead, Cambridge Astrophysics Series, Cambridge University Press, 1991, XXIII+ 498 pp., £70.00 UK (ISBN 40-521-40325-1).

ISSN:0309-1929    

DOI:10.1080/03091929208229060

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor