Hunting the Universe’s First Stars with Gravitational Lenses
Population III stars formed from pristine gas roughly 100–250 million years after the Big Bang and, if massive, burned bright for only a few million years before dying and seeding heavier elements. No individual Pop III star has been definitively identified, largely because their light is faint and rare to spot, but gravitational lensing by galaxy clusters—along with JWST’s infrared power—offers a path to detect them. Earendel, a highly magnified star behind a foreground cluster, demonstrates the lensing method, though it is not a Pop III star. Detecting a true first star would require precise lens models and spectroscopy proving a pristine, metal-free atmosphere, plus accounting for microlensing variability. A confirmed Pop III detection would illuminate the early mass distribution of the first stars and the timeline of metal enrichment, though such a star may still remain elusive across the cosmos.
