Astronomers are seeking to explore a little-studied time in our universe's history known as "the Dark Ages." The universe was dark in that no galaxies shined brightly as we see today. Yet somehow, out of this dark, mostly-hydrogen gas, the very first stars did form somehow, lighting up the cosmos for the very first time.
What these first stars were like is still a debate amongst astronomers since there is a lack of direct observations.
Astronomers can simulate the formation of stars under the conditions that were present in the very early universe. However, the scenario is complex on large and small scales and involves many physical and chemical processes, all which need to be tracked carefully.
Often, some assumptions and approximations must be made in order for the simulation to fit into a realistic computational space and time.
Many previous models of the first stars were semi-analytic, meaning that some processes were approximated through the use of equations, rather than just letting the simulation progress in a purely numerical way. These have long predicted that, in the absence of heavier elements such as carbon, nitrogen, and oxygen, that the first stars would be truly massive, reaching hundreds of times the mass of the sun before finishing their growth.