Composite Polytropes

Composite polytropes are an extension of standard polytrope models for stellar structure, to allow for discontinuities in the density \(\rho\) and/or the polytropic index \(n\). This appendix lays out the mathematical formalism1 underpinning them; it is intended to complement the Building POLY Models appendix, which describes how composite polytrope models can be built using the build_poly executable.

• Equation of State
• Structure Equations
  • Lane-Emden Equation
  • Continuity Relations
• Solution Method
  • Specification
  • Solution
• Physical Variables
• Structure Coefficients

Footnotes

1

The formalism here is based on Mixed polytrope with density discontinuities (Christensen-Dalsgaard, 2015, unpublished), with extensions to allow for constant-density regions.