In a small galaxy, located on the edge of the Milky Way, light years away, astronomers discovered one of the most chemically primitive stars ever recorded. The star, named PicII-503, lacks heavy elements, leading scientists to believe it is from the second-generation of stars that formed shortly after the Big Bang.
The star likely contains traces of chemicals that made up the very first stars ever formed, and has the ability to provide unique insight into how stars formed during initial stages of chemical enrichment.
Astronomers have only found around 10 stars as chemically lacking as PicII-503 within the Milky Way, and many believe that these stars once belonged to older galaxies but were absorbed by the Milky Way over time.
In 2024, scientists, using a telescope located in Chile discovered the PicII-503 star, and through many observations, have detected extremely low quantities of iron and calcium, with contrastingly high levels of carbon. This data indicates that the star was formed in the early stages of the universe.
First-generation stars were made entirely out of hydrogen and helium. When they died out and became supernovas, these elements fused together, helping to create new elements. First-generation stars didn’t last very long, but the new elements they created and the particles they left behind allowed for second-generation stars to live long lives, with some surviving 12 billion years.
In addition, the extreme rates of iron and calcium in PicII-503 suggest that the star formed with materials from only one supernova, putting it at the beginning of the second-generation.
Also, astronomers are able to deduce that, since there is an excess of carbon, the first supernovas had relatively low energy levels and were only able to eject relatively light elements such as carbon, while heavier elements like iron fell back into their cores.
Scientists predict that they will continue to discover more second-generation stars and early galaxies, helping them to better understand the chemical enrichment of the universe over time.
