The Contribbution of Coulombic Pressure to the Stability of thin Keplerian Accretion Discs Around a Neutron Star with Axisymmetric Magnetic Dipole
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Date
2013-06
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Addis Ababa University
Abstract
Based on the contribution of intraction between various charged components
of the system the stability analysis of an axisymmetric geometrically thin and
optically thick accretion disk around a magnetized neutron star is presented.The
disk we consider is modi ed by including the e ect of coulombic pressure on the
total pressure.We consider three region of the disks outer, middle and inner region.
The outer and middle region of the disk is dominated by gas pressure and
the inner region is dominated by radiation pressure. The opacity in the middle
and inner region is mainly due to electron scattering whereas that in the outer
region is mainly due to free-free emission. Starting from the vertically integrated
non-relativistic hydrodynamics equations we set up the basic equations which govern
the structure of the disc and for the stability analysis of the disc model we
have kept the time dependencies in the equations. Even if we include coulombic
pressure We nd that the gas pressure dominated region is thermally stable.The
graph of stability parameter as afunction of the disk radius shows that the inner
region of the disc is viscously unstable
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Keywords
The Contribbution of Coulombic Pressure