Accretion by magnetic neutron stars. I - Magnetospheric structure and stability

Results are presented of a detailed study of the magnetic neutron star model, taking into account the particular case in which the accretion flow is approximately radial and the star is slowly rotating. An investigation is conducted of the physical processes which occur in the neighborhood of the magnetospheric boundary and, in particular, on the manner in which accreting plasma enters the magnetosphere. Attention is given to the formation of a magnetosphere, the scale and structure of static magnetospheres, equilibrium shapes, the stability of the magnetospheric boundary, the plasma flow into the magnetosphere, the scale and structure of the magnetosphere, and the Alfven surface. The presented results imply that, for a wide range of conditions relevant to compact X-ray sources, the Rayleigh-Taylor instability is the most important plasma entry process.