Pristine star reveals the dawn of stars and galaxies.

Astronomers report that the red giant SDSS J0715-7334 is the most chemically pristine star known, with an extremely low metallicity, and its composition provides evidence that dust-driven cooling helped form low-mass stars.

SDSS J0715-7334 is a red giant whose spectrum shows almost no heavier elements, making it chemically very primitive. Researchers say this star likely formed from material affected only by the earliest stellar deaths. The object was flagged in data from the SDSS-V survey and confirmed with high-resolution spectra from the Magellan telescopes at Las Campanas Observatory. The discovery and analysis are reported in Nature Astronomy. Key findings: - SDSS J0715-7334 is described as the most pristine star known because its spectrum shows barely any heavier elements. - The team reports a metallicity upper limit of less than 7.8 × 10⁻⁷, equivalent to under 0.005 percent of the Sun's metal content and about twice as metal-poor as the previous record. - Iron and carbon levels are especially low, and the low carbon abundance implies the star likely did not form via atomic fine structure cooling, leaving dust cooling as the required mechanism. - The candidate was identified in SDSS-V survey data and confirmed during follow-up observations with Magellan instruments at Las Campanas Observatory. - The star lies about 80,000 light-years away and is likely to have formed in or near the Large Magellanic Cloud before being pulled into the Milky Way. - The elemental pattern was matched to Population III supernova models, with a best-fit progenitor around 27 solar masses and a high explosion energy; the authors note the metallicity estimate depends on assumptions about unmeasured elements such as nitrogen and oxygen. Summary: This star provides a cleaner local benchmark for testing how the first stars enriched the cosmos and supports evidence that dust-driven cooling enabled later low-mass star formation beyond the Milky Way. The analysis links the star's chemistry to models of early metal-free supernovae, while also noting uncertainties tied to unmeasured elements. More examples of similarly metal-poor stars in varied environments will be needed to test broader ideas about earliest star formation.