Study links early JWST 'Little Red Dots' to formation of globular clusters
Researchers propose that the compact, red objects observed by the James Webb Space Telescope around 600 million years after the Big Bang could be nascent globular clusters containing short-lived supermassive stars.
Astronomers have identified a possible connection between the compact, red sources detected by the James Webb Space Telescope (JWST) in the early universe and the later-forming globular clusters that populate modern galaxies. The objects, dubbed “Little Red Dots,” appear in large numbers about 600 million years after the Big Bang and seem to vanish by the time the universe reaches roughly two billion years old.
A research team from the University of Texas at Austin suggests that these sources may be forming globular clusters that host supermassive stars—hypothetical stars with masses between 1,000 and 10,000 times that of the Sun. Such stars would burn intensely for about a million years, producing the high-temperature nuclear fusion required to create the unusual chemical abundances observed in present-day globular clusters.
"These may not be just a strange new JWST population with no connection to the universe around us today," team leader John Chisholm said in a statement. "Instead, Little Red Dots may persist past the early universe, evolving into something relatively familiar."
"In our model, the supermassive star that helps make the object look like a Little Red Dot would live for only a short time," Chisholm added. "Once that star dies, the object may no longer look like a Little Red Dot, even if the cluster itself survives billions of years."
Globular clusters are dense assemblies of up to millions of ancient stars that are typically observed in large galaxies, including the Milky Way, which hosts at least 150 such clusters. Their formation mechanisms remain uncertain, but the new model aligns several observational clues: the timing of Little Red Dot appearance matches estimates for the onset of globular cluster formation; the estimated masses of the early objects are compatible with the masses of modern clusters; and the peculiar chemical signatures—high helium and certain heavy elements with low carbon, oxygen, and magnesium—can be explained by nucleosynthesis in supermassive stars.
"There's no single smoking gun at this point that says Little Red Dots are globular clusters, but it would explain a lot of diverse and surprising observations," said co-author Mike Boylan-Kolchin.
If confirmed, the hypothesis would provide a direct observational link between the earliest star-forming structures and the ancient stellar systems that survive today.