Stellar atmosphere models for Population III stars

Abstract: The  rst stars to illuminate the universe are said to belong to a group called Population III. Having knowledge of their atmospheric conditions would be useful in many endeavours. The aimof this project was to compile and run the FORTRAN code TLUSTY (Hubeny and Lanz 2017) inorder to create stellar atmospheres for Pop III stars. With a working version of TLUSTY, severalcontrol runs were then performed to make sure that everything worked as intended with the  final goal to create a large grid of calculated atmospheres in the parameter space of effective temperatureand surface gravity. Successful comparisons were made against earlier calculations made by Schaerer(2002) and Windhorst et al. (2019). Constructing such a grid required several codes to work togetherwith TLUSTY by constructing a shell script. The result is a grid  lled with many points that werewell converged, as well as a few that did not appear to converge. Comparing the converged part ofthe grid with stellar evaluations tracks made by Yoon et al. (2012) showed that heavy, rotating PopIII stars fell almost within the grid. One problem that arose, however, was that as the grid did notfully converge all the way to the tracks some could not be uniquely mapped to di erent points on thegrid. Thus, some di erent tracks would become degenerate which should not be physically expected. However this may not be a fatal problem.