doi.org/10.1038/s41550-026-02802-z
Credibility: 989
#Universe
A team of astronomers has identified one of the most primitive and chemically pure stars ever recorded, a true living fossil of the early universe
Called PicII-503, this star has an incredibly low amount of iron: only 1/40,000th of that found in the Sun.
This characteristic places it among the poorest objects in heavy metals known, approaching what is expected of the first stars that emerged after the Big Bang.
What makes PicII-503 especially valuable is the fact that it clearly and unambiguously preserves the chemical signature of the first stars that existed in the cosmos.
These stars of the so-called Population III were composed almost exclusively of hydrogen and helium, the only elements produced in the Big Bang.
When they exploded as supernovae, they scattered heavier elements-such as carbon, oxygen, and iron-into space, enriching the material that would give rise to subsequent generations of stars.
Most very old stars we find today carry mixed signals, the result of several generations of enrichment.
However, PicII-503 stands out for clearly showing the products of only one or a few primordial supernovae, without significant contamination from later processes.
This makes it a direct window into understanding what the first nucleosynthesis events in the universe were like.
Interestingly, the discovery occurred in an ultrafaint dwarf galaxy, a type of small, low-luminosity star system that orbits our Milky Way and tends to preserve very old objects.
PicII-503 represents the clearest and most extreme example of a second-generation star found in this environment, with the lowest iron content ever measured in an ultrafaint dwarf galaxy.
The researchers emphasize that finding a star that so clearly preserves the heavy elements produced by the first stars was at the limit of what they considered possible, given the extreme rarity of these objects.
This discovery opens a unique opportunity to study the initial production of chemical elements in primordial systems, helping to reconstruct the conditions of the universe in its earliest moments.
Published in 03/23/2026 00h19
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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