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Accretion Disk Electrodynamics

  • M. Kuperus
Part of the NATO ASI Series book series (NSSB, volume 156)

Abstract

A plasma cloud orbiting around a compact object of mass M with the Kepler velocity vϕ = (GM/ r)1/2 at a distance r from the center of the object has an angular momentum I = mΩr2 , where m is the mass of the cloud and Ω = vϕ/r is tne angular velocity. The inner parts of the cloud have a larger angular velocity then the outer parts do thus creating a shear. The result of this differential rotation is twofold. First the cloud is stretched in the azimuthal direction until a ring is formed. Secondly because of the shear the cloud diffuses in the radial direction transporting mass inward as well as outward. The innermost parts of the ring are slowed down due to the viscous drag caused by the slower moving outer parts while the outer parts are accelerated due to the viscous drag of the faster moving inner parts. Consequently the inner parts start drifting inwards and the outer parts start drifting outwards. Since the angular momentum is proportional to r2 the outflowing parts of the plasma cloud transport more angular momentum outward then the inward moving parts transport inward. Due to the viscous processes inside the disk the outward transport of angular momentum is achieved thus facilitating the process of accretion.

Keywords

Angular Momentum Neutron Star Accretion Disk Differential Rotation Compact Object 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • M. Kuperus
    • 1
  1. 1.Observatory “Sonnenborgh”University of UtrechtUtrechtNetherlands

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