Astronomers recently announced the discovery of a star described as the “purest star” ever detected. This rare star was discovered on the outskirts of the Milky Way galaxy and is thought to be the descendant of one of the first stars in the universe.
Its special feature lies in its very low metal content, so its existence challenges the basic understanding of how stars can form. In the world of astronomy, the level of heavy elements or metallicity of a star is an important marker of its origin.
Stars with high metallicity usually form from the remains of previously exploded stars. Meanwhile, stars with low metallicity are considered “pure” because they are composed almost entirely of hydrogen and helium, the elements that dominated the universe after the Big Bang.
Ancient stars like these are highly sought after because they provide direct clues about the early conditions of the cosmos. However, so far no first generation stars have been directly observed.
In the latest research uploaded to the arXiv preprint server on September 25, 2025, researchers reported the discovery of a new star named SDSS J0715-7334. This star has the lowest level of metallicity ever recorded, surpassing all previously known stars.
The detection of J0715-7334 was carried out through the MINESweeper program, which searches data from the European Space Agency’s Gaia space telescope. This star is classified as a red giant with a mass of about 30 times the mass of the Sun.
The uniqueness of J0715-7334 lies not only in its very low metal content, but also in its carbon content which is much lower than other low-metal stars. Usually, stars with little metal still show quite high carbon contents, but this is not the case with J0715-7334. This strengthens the suspicion that this star is a descendant of the first generation of stars formed from pure hydrogen gas left over from the Big Bang.
Based on analysis of its angular momentum, the researchers estimate that J0715-7334 originated in the Large Magellanic Cloud, a small galaxy containing about 30 billion stars, which was then drawn into the Milky Way. Its distance from Earth is estimated to be around 85,000 light years, although the exact value is still difficult to ascertain.
This discovery was an important breakthrough for modern astronomy. J0715-7334 may provide new insight into how metal-deficient stars form, although conventional theory suggests that such conditions should make star formation nearly impossible. Thus, the existence of this star is a door to retracing the early history of the universe and the birth process of the first stars.
Source: livescience.com
