Population III Stars and Evolutionary Stellar Metallicity

Study of the early Universe is filled with many unknowns, one of which is the nature of the very first generation of stars, otherwise designated as "Population III stars". The early Universe was composed almost entirely of cold hydrogen and helium, with only trace amounts of any heavier elements. As such, these stars would have compositions very different from the stars we are able to observe today, which would in turn change how these stars functioned, as well as their lifespans. Population III stars are so old that the light they emitted has not yet reached us here on Earth. Yet we know they have to have existed, so how do we go about studying objects that we have not yet observed? And more importantly, is there a metallicity threshold at which stars begin to behave like the stars we observe today? These areas are where stellar modelling programs such as TYCHO8 and the Spanish Virtual Observatory's Theoretical Spectra Web Server (TSWS) come in. These programs allow astronomers to model the physics of Pop III stars. We can get a pretty good understanding of how these stars behaved, how long they lived, and the visual spectra they would have emitted. Such information is crucial to astronomers being able to search for remnants of these stars, and one day, the stars themselves.