Author(s) :

Christopher Ann, Ryan J. Farber.

Volume/Issue :

Abstract :

Since Joseph von Fraunhofer’s 1814 discovery of solar absorption lines, spectroscopy has become central to understanding stellar composition and the process of star formation. Building on the foundational contributions of Kirchhoff, Bunsen, and Payne-Gaposchkin, modern astrophysics has examined metallicity (the abundance of elements heavier than hydrogen and helium) as a key factor in star formation processes and the Initial Mass Function (IMF). Observational surveys and simulations suggest that metallicity influences stellar fragmentation, cooling, and feedback, with lower metallicities often favoring more massive stars. The mass-metallicity relation (MZR) and its evolution further underscore how galaxy growth, star formation rates, and feedback mechanisms influence metallicity trends over time. However, the role of metallicity remains complex and contested, with turbulence, accretion history, and environmental factors playing equally significant roles. The case of Population III stars (formed in metal-free environments) demonstrates that stellar mass can arise independently of metallicity, emphasizing the limits of a universal link between metallicity and IMF. This review synthesizes key observational evidence, theoretical models, and limitations, concluding that metallicity is a central but non-exclusive factor in determining stellar mass. Future progress will rely on integrating high-resolution simulations, advanced stellar population models, and next-generation observations, particularly from JWST, to clarify the exact relationship between metallicity and other environmental drivers of star formation.