Astronomers have discovered an ancient, chemically primitive star within the faint dwarf galaxy Pictor II. The star, designated Pristine_221.8781+9.7844, is extremely metal-poor, indicating it formed from material enriched by only one or a few previous supernovae from the Universe's first generation of stars.
The discovery, led by researchers from the University of Toronto and published in the journal 'Science', was made using the Canada-France-Hawaii Telescope and follow-up observations with the Magellan Telescopes. The star's chemical fingerprint provides a direct record of the nucleosynthesis from the earliest supernovae, which were likely very massive and energetic.
Located about 290,000 light-years away, Pictor II is an ultra-faint dwarf galaxy orbiting the Milky Way. Such galaxies are considered cosmic archaeological sites, as their stars formed early and have experienced little subsequent chemical enrichment, preserving the conditions of the early Universe.
This finding helps constrain models of the first stars (Population III) and the early chemical evolution of galaxies. Studying more such stars in faint dwarf galaxies is a key goal for next-generation telescopes like the James Webb Space Telescope and the upcoming Extremely Large Telescope.
