Basic Stars, Basic MESA

Reading Assignment

Observations of Stars

How to get MESA?

Download the MESASDK from http://www.astro.wisc.edu/~townsend/static.php?ref=mesasdk and unpack
Download the recent MESA source by following the instructions at http://mesa.sourceforge.net
Create your setup.sh script to setup the environment variables for MESA and the MESASDK
Run the setup.sh script
Go to the MESA directory and run "./install"
Get more help at http://mesastar.org/
If you want to install ctioga2 with your MESASDK, follow my instructions at Ctioga2.

You can also use MESA-Web until you get your own copy working or Cocalc. If you have trouble installing your copy, please try

What does MESA do?

MESA Inlists:

sample_zams
create_zams

Assignment

Part 1

Using the estimate of the central temperature of the Sun that I derived in class and the equation for radiative energy transport, estimate the luminosity of the Sun if the opacity is given by electron scattering 0.4 cm²g^-1 or by free-free opacity using the mean density and the central temperature of the Sun. Here is the formula for the absorption coefficient in c.g.s. units and its relationship to the free-free opacity $\kappa _{ff}$ :

$\alpha _{ff}=\kappa _{ff}\rho =1.7\times 10^{-25}T^{-7/2}n_{e}n_{i}g_{R}$

Take $Z=g_{R}=1$ . $n_{e}$ and $n_{i}$ are the number densities of electrons and ions respectively. $Z$ is the atomic number and $g_{R}$ is the Rosseland mean Gaunt factor.

Part 2

Complete the MESA exercises at the end of chapter one of Stellar Astrophysics .

The easiest way to get the code for the exercises is to download the repository on GitHub at [1].

Also please download [2] to help you get started with MESA>