Accretion by rotating magnetic neutron stars. II. Radial and vertical structure of the transition zone in disk accretion

Journal Article · Wed Aug 15 04:00:00 EDT 1979 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/157285· OSTI ID:5759709

Ghosh, P; Lamb, F K

We invesgitage the interaction between the stellar magnetic field and the accreting plasma at the magnetospheric boundary of a neutron star accreting matter from a disk. The stellar magnetic field penetrates the inner part of the disk via the Kelvin-Helmholtz instability, turbulent diffusion, and reconnection, producing a broad transition zone joining the unperturbed disk flow far from the star to the magnetospheric flow near the star. Using the two-dimensional hydromagnetic equations, we calculate the inner and outer radii of this zone and its radial and vertical structure. The transition zone is composed of two qualitatively different regions, a broad outer zone where the angular velocity is Keplerian and a narrow inner zone or boundary layer where it departs significantly from the Keplerian value. The star's magnetic field is only slightly deformed within the boundary layer but becomes increasingly distorted at larger radii.We discuss the implications of the flow solutions found here for neutron-star models of accreting X-ray sources, considering in turn the flow of matter from the inner edge of the disk to the surface of the star, the resulting accretion torque, and the pattern of falling plasma at the stellar surface. Because approx.20% of the star's magnetic flux threads the disk outside its inner edge, plasma channeled by the magnetospheric field falls in a circular ring at the magnetic poles.

• Research Organization: Department of Physics, University of Illinois at Urbana-Champaign
• OSTI ID: 5759709
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 232:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BOUNDARY LAYERS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
FLUID FLOW
FLUID MECHANICS
HELMHOLTZ INSTABILITY
HYDRODYNAMICS
INSTABILITY
LAYERS
MAGNETIC FIELDS
MAGNETIC STARS
MAGNETOHYDRODYNAMICS
MASS TRANSFER
MATHEMATICAL MODELS
MECHANICS
MOTION
NEUTRON STARS
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
ROTATION
STAR ACCRETION
STAR EVOLUTION
STAR MODELS
STARS
STELLAR ATMOSPHERES
STELLAR MAGNETOSPHERES