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Are the Cosmic Gems the earliest star clusters ever detected?
Observations might have uncovered star clusters that existed when the Universe was just 460 million years old. If this timing is accurate, the discovery provides valuable clues about how and when the first stars formed.
Star clusters are collections of thousands to millions of stars bound together by gravity — and many can be observed in the night sky with binoculars or a small telescope. One notable example is ω Centauri, a cluster containing millions of stars, which was first catalogued as a single star by Greek mathematician Ptolemy in ad 150, and then later as a cluster by English astronomer Edmond Halley in 1677. But despite this long history of observing these objects, and decades of research, one question has remained: when were the first star clusters born? Writing in Nature, Adamo et al.1 report a discovery that could provide the answer, using observations by the James Webb Space Telescope (JWST) of a group of star clusters dubbed the Cosmic Gems. These star clusters contain millions of stars, and probably formed during the Universe’s first era of star formation, known as the cosmic dawn.