By B. Paxton et al. (2011) and the MESA developers
What it does
Given an initial mass, composition and input physics (equation of state, opacities, nuclear reaction network, mixing), MESA solves the coupled equations of stellar structure and composition on an adaptive mesh and steps the star through time. It writes a history of global quantities such as temperature, luminosity, radius and age, and profiles of every quantity from centre to surface.
The code is described in Paxton et al. (2011) and in the instrument papers that followed. It is open source, written and maintained by a distributed team, the MESA developers.
How I used it
I did not run MESA. I worked with MESA evolutionary tracks as the model grid behind PARAM, and plotted grid tracks for the figures of my MSc thesis (Sect. 2.6 and 5.2).
The animation
The track is a real 1 solar-mass, solar-metallicity MESA track, the one behind Stellar Explorer, from MESA models run by R. Costa (IA Porto). The dot follows that track. The depth of the convective envelope, the burning region, the interior temperature on the cut faces and the surface colour are set at every step from the track's stored interior profiles.
The star's size on screen (a logarithmic scale), the granulation, the glow and the colours are drawn.