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

Journal Article · Mon Aug 01 04:00:00 EDT 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155427· OSTI ID:7082901

Elsner, R F; Lamb, F K

The results of a study of accretion by a slowly rotating, magnetic neutron star when the accretion flow is approximately radial are presented. The physical processes that occur in the neighborhood of the magnetospheric boundary and the manner in which accreting plasma enters the magnetosphere are examined, and the conditions necessary for the formation of a magnetospheric cavity and for its stability are investigated. Although the boundary of the cavity is initially close to instability, magnetospheric models strongly suggest that it is stable until the plasma outside undergoes at least some cooling. Assuming that little plasma enters the magnetosphere when the boundary is stable, there is, typically, time for the plasma outside to form a quasi-static atmosphere around the magnetosphere before instability sets in. The scale and structure of such static configurations, including the nature of the current layer at the magnetospheric boundary are discussed, the structure of the magnetosphere when there is a steady inflow of plasma across the boundary is investigated, and the possible flow patterns at the boundary and in the interior are discribed. Assuming that plasma enters the magnetosphere predominantly via Rayleigh-Taylor instability of the boundary, the conditions necessary for a steady accretion flow are considered, and it is noted that beaming of x-rays from the stellar surface can strongly affect the plasma flow pattern near the boundary. The Alfven surface generally does not coincide with the magnetospheric boundary and could conceivably lie well within it. A discussion of the present study shows that it may apply directly to the longer-period pulsating x-ray sources, if the accretion flow is sufficiently radial, and to some x-ray burst sources, if these are slowly rotating neutron stars.

• Research Organization: Department of Physics, University of Illinois at Urbana-Champaign
• OSTI ID: 7082901
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 215:3; 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
COOLING
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
MAGNETIC FIELDS
MAGNETIC STARS
MATHEMATICAL MODELS
MECHANICS
MOTION
NEUTRON STARS
PLASMA
RADIATIVE COOLING
RAYLEIGH-TAYLOR INSTABILITY
ROTATION
STAR ACCRETION
STAR EVOLUTION
STAR MODELS
STARS