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Astronomers Identify Most Chemically Pristine Star Ever Observed

Its near-absence of heavy elements gives a clean test of how the first supernovae seeded later generations of stars.

Overview

  • A Nature Astronomy study reports SDSS J0715−7334 as the new record holder for stellar purity, making it the most metal-poor star measured to date.
  • Spectra show less than 0.005% of the Sun’s heavy elements, with exceptionally low iron and carbon, which is about twice as metal-poor as the prior record.
  • The star sits roughly 80,000 light-years from Earth, and Gaia data indicate it migrated into the Milky Way from outside the galaxy.
  • Researchers first flagged the target in Sloan Digital Sky Survey data, then confirmed its chemistry with high-resolution observations at the Magellan telescopes in April 2025.
  • The finding points to a likely second-generation relic that tightens limits on early supernova yields and tests whether cosmic dust was needed to form small, long-lived stars.