What name is given to the first generation of stars formed from pristine gas in the early universe?

The first generation of stars formed from pristine gas in the early universe is called Population III.

Population III stars formed from material containing almost no elements heavier than hydrogen and helium. Those heavier elements, often called metals by astronomers, had not yet been created in stars. The gas came primarily from the early universe’s original hydrogen and helium, with a small amount of lithium.

Because metal-free gas cools less efficiently than enriched gas, Population III stars may have formed differently from later stellar generations. Many models predict that some were extremely massive and short-lived. Their nuclear fusion and supernovae would have created and dispersed the first substantial quantities of heavier elements, helping prepare gas clouds for later stars and planets.

No confirmed Population III star has been observed directly. Their likely great distance and ancient age make them difficult to detect, but astronomers search for their chemical signatures and possible effects on early galaxies. Population II stars are also old and metal-poor, but they formed after earlier stars had already enriched the universe.