Astronomers Discover Ancient Star PicII-503 in Dwarf Galaxy Pictor II

Astronomers have identified PicII-503, a star located in the ultra-faint dwarf galaxy Pictor II, approximately 150,000 light-years from Earth in the constellation Pictor. This star exhibits an exceptionally low iron content—less than 1/40,000th that of the Sun—and a significant overabundance of carbon. These characteristics suggest that PicII-503 is a second-generation star, formed from material enriched by the first stars in the universe.

The discovery was made using the Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory in Chile. The research team, led by Anirudh Chiti of Stanford University, conducted a survey called MAGIC (Mapping the Ancient Galaxy in CaHK) to identify such chemically primitive stars.

"Discovering a star that unambiguously preserves the heavy metals from the first stars was at the edge of what we thought ... ," said Chiti. "With the lowest iron abundance ever ... ."

The findings support the hypothesis that carbon-enhanced metal-poor stars like PicII-503 originated from low-energy supernovae of the first stars. In such explosions, lighter elements like carbon were expelled into space, while heavier elements like iron remained in the remnants. This process contributed to the chemical evolution of subsequent generations of stars.

The study was published in Nature Astronomy on March 16, 2026.