ASTR 530/CSI 661 Fall 2005

Dr. John Wallin

Lane-Emden Solutions


In this homework, you are going to compare a very simple stellar model to the "Standard Solar Model" created by John Bahcall. The idea is to see the limits of the Lane-Emden equation with different polytropic indices. You will run models for n= 1, 1.5, 2, 2.5, 3, 3.5 and compare the density, temperature, pressure, and cumulative mass as a function of radius to the standard model.

When you do this comparision, please put all the different models on the same graph, so that you have lines for pressure vs radius for n=1, 1.5.... and the Bahcall model all on the same graph.

Write a short (1 page) summary of the conclusions of this comparision.

As an extra credit assignment, you may write a code that solves the Lane-Emden equation numerically. You may use matlab, octave, or a similar program to do this calculation.