Discovery of Ancient Star Sheds Light on Early Universe Element Formation

Astronomers have discovered a second-generation star, designated PicII-503, within the ultra-faint dwarf galaxy Pictor II, approximately 150,000 light-years from Earth. This star exhibits the lowest iron abundance ever detected outside the Milky Way—only 1/40,000th that of the Sun—and a carbon-to-iron ratio over 1,500 times greater than that of the Sun.

The chemical composition of PicII-503 suggests it formed from material enriched by the universe's first generation of stars, known as Population III stars. These massive stars, composed primarily of hydrogen and helium, produced heavier elements like carbon and iron through nuclear fusion. Upon their deaths in low-energy supernovae, they expelled lighter elements into space while retaining heavier ones, influencing the makeup of subsequent generations of stars.

The discovery was made using the Dark Energy Camera (DECam) and confirmed with observations from the Magellan Telescopes and the European Southern Observatory’s Very Large Telescope. Anirudh Chiti, the study's lead author and a postdoctoral researcher at Stanford University, stated,

"Discovering a star that unambiguously preserves the heavy metals from the first stars was at the edge of what we thought possible, given the extreme rarity of these objects."

This finding provides a rare glimpse into the early processes of element formation in the universe, offering valuable insights into the chemical evolution of galaxies.