The universe’s first generation of stars was crucial in transforming the cosmos. These stars, born from simple hydrogen and helium, fused these elements into various new elements. When these stars reached the end of their lives, they exploded, scattering these newly formed elements throughout the universe. As a result, elements such as iron, calcium, and sodium, essential to life, originated from the remnants of these ancient stars.

Recently, scientists made a groundbreaking discovery related to the second generation of stars. While the first generation remains elusive, a star from the second generation, which initially formed in a different galaxy from ours, has been identified. This finding provides a unique opportunity to gain insights into the early element-forming processes in galaxies beyond our own.

Anirudh Chiti, a postdoctoral fellow at the University of Chicago, and his team specialize in stellar archaeology, which involves reconstructing how the earliest generations of stars shaped the universe. Their research aims to understand the properties of the first stars and the elements they produced. However, directly observing these first-generation stars has proven challenging. Instead, the team searches for stars formed from the first generation’s remnants, akin to “fishing needles out of haystacks.”

In a recent study published in Nature Astronomy, Chiti and his colleagues focused on the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way. The team made a remarkable discovery by examining the LMC’s ancient stars, which offer unique insights into early star formation and nucleosynthesis. They identified a star with significantly lower levels of heavier elements than any other star previously observed in the LMC. This suggests that the star likely formed in the aftermath of the first generation of stars, before the buildup of heavier elements through subsequent star births and deaths.

Furthermore, the star’s elemental composition, particularly its low carbon content relative to iron, indicates potential differences in the early element enrichment processes between the LMC and the Milky Way. These findings shed light on the environment-dependent nature of early element production, driven by the earliest stars.

Chiti and his team’s ongoing research aims to map out a large portion of the southern sky to identify more of these ancient stars in the LMC. Their work promises to provide detailed insights into how the first stars chemically enriched the universe in different regions, offering an exciting glimpse into the early history of our cosmos.

References

• Chiti, A., Mardini, M., Limberg, G., Frebel, A., Ji, A. P., Reggiani, H., Ferguson, P., Andales, H. D., Brauer, K., Li, T. S., & Simon, J. D. (2024). Enrichment by extragalactic first stars in the Large Magellanic Cloud. Nature Astronomy, 1–11. https://doi.org/10.1038/s41550-024-02223-w
• University of Chicago. (2024, March 20). Scientists find one of the most ancient stars that formed in another galaxy. Phys.Org; Phys.org. https://phys.org/news/2024-03-scientists-ancient-stars-galaxy.html