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Polytropic gas spheres: An approximate analytic solution of the Lane-Emden equation

F. K. Liu
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Abstract

Polytropic models play a very important role in galactic dynamics and in the theory of stellar structure and evolution. However, in general, the solution of the Lane-Emden equation can not be given analytically but only numerically. In the Lane-Emden equation can not be given analytically but only numerically. In this paper we give a very good and simple analytic approximate solution of the Lane-Emden equation. This approximation is very good for any finite polytropic index $n$ and for the isothermal case (n equals infinity) at a level $<1\%$. We also give analytic expressions of the mass, pressure, temperature, and potential energy as a function of radius.

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F. K. Liu. 1995-12-11. Polytropic gas spheres: An approximate analytic solution of the Lane-Emden equation. https://doi.org/10.1093/mnras%2F281.4.1197

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