The Structure of Self‐gravitating Polytropic Systems withnaround 5

We investigate the structure of self-gravitating polytropic stellar systems. We present a method which allows to obtain approximate analytical solutions, $\psi_{n+\epsilon}({\bf x})$, of the nonlinear Poisson equation with the polytropic index $n+\epsilon$, given the solution $\psi_n({\bf x})$ with the polytropic index n, for any positive or negative $\epsilon$ such that $|\epsilon|\ll1$. Application of this method to the spherically symmetric stellar polytropes with $n\simeq5$ yields the solutions which describe spatially bound systems if n5. A heuristic approximate expressions for the radial profiles are also presented. Due to the duality between stellar and gas polytropes, our results are valid for gaseous, self-gravitating polytropic systems (e.g., molecular clouds) with the index $\gamma\simeq 6/5$. Stability of such systems and observational consequences for both stellar and gaseous systems are discussed.
Comment: LaTeX, emulateapj, 5 pages, 2 PS figures. ApJ,accepted version. Other works are at http://www.cita.utoronto.ca/~medvedev/