Homogeneous spheres with constant adriatic index |
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Authors: | MC Durgapal PS Negi |
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Institution: | (1) Department of Physics, Kumaun University, Nainital –, 263 002, India |
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Abstract: | Compressible homogeneous spheres with constant adiabatic index γ were studied for their dynamical stability by Chandrasekhar
and he found that for each value of u (≡ mass to size ratio), there is a value of γ = γc, such that for γ < γc, the configuration is dynamically unstable. On examining the properties of the Chandrasekhar's spheres (homogeneous spheres
with constant γ) it is found that these spheres are non-isentropic, and the speed of sound within these spheres is finite.
The authors find that (i) for the causality condition to be fulfilled throughout the configuration, the value of γ ≤ 2/(surface
redshift)], (ii) for a given value of u, the binding coefficient, αr = (Mr -M)/M, vanishes for some value of γ = γb and for all the values of γ < γb the configurations are unbound, and (iii) for u≤ (1/3), one can find configurations which are bound, dynamically stable, and the speed of sound is less than that of light
throughout the configuration, whereas, for u >(1/3), the physically viable models of homogeneous density distribution are not possible. If the configuration is considered
to be isentropic, then both γ and the speed of sound become infinite throughout the configuration.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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