%0 Journal Article
%T The Intrinsic Beauty of Polytropic Spheres in Reduced Variables
%A Roberto Caimmi
%J International Journal of Astronomy and Astrophysics
%P 236-246
%@ 2161-4725
%D 2016
%I Scientific Research Publishing
%R 10.4236/ijaa.2016.63019
%X The concept of reduced variables is revisited with regard to van der Waals¡¯ theory and an application is made to polytropic spheres, where the reduced radial coordinate is
, R radius, and the reduced density is
,
central density. Reduced density profiles are plotted for several polytropic indexes within the range, 0¡Ün¡Ü5, disclosing two noticeable features. First, any point of coordinates, (w, v), 0¡Üw¡Ü1, 0¡Üv¡Ü1, belongs to a reduced density profile of the kind considered. Second, sufficiently steep i.e. large reduced density profiles exhibit an oblique inflection point, where the threshold is found to be located at n=nth=0.888715. Reduced pressure profiles,
,
central pressure, Lane-Emden fucntions,
, and polytropic curves, q=q(v), are also plotted. The method can be extended to nonspherical polytropes with regard to a selected direction,
. The results can be extended to polytropic spheres made of collisionless particles, for polytropic index within a more restricted range, 1/2¡Ün¡Ü5 .
%K Stars: Equilibrium
%K Galaxies: Equilibrium
%K Polytropic Spheres
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=69664