Astronomers may have found an answer to two long-standing mysteries about the universe with a single new idea.
A study led by researchers at The University of Texas at Austin suggests that mysterious objects known as “Little Red Dots” may actually be the earliest stage in the life of globular clusters, some of the oldest groups of stars in the universe.
The findings, published in The Astrophysical Journal Letters, propose that these two puzzling objects are not separate at all.
Instead, Little Red Dots could be the ancestors of the ancient globular clusters that still orbit galaxies today.
Little Red Dots were first discovered in 2022 by the James Webb Space Telescope (JWST).
They appear about 600 million years after the Big Bang, shine brightly with a distinctive mix of red and ultraviolet light, and then seem to disappear around 1.5 billion years after the universe began. Their unusual appearance has left astronomers searching for an explanation.
One leading idea has been that these objects contain supermassive black holes hidden inside thick clouds of gas. In this scenario, the black holes consume nearby stars, creating the light signals detected by JWST.
While this theory explains many of the observations, it is not the only possibility.
The new study proposes another explanation. The researchers suggest that Little Red Dots may instead be young globular clusters containing an enormous star at their center. This giant star, known as a supermassive star, could make the cluster appear just like a Little Red Dot during its earliest stage.
Globular clusters are tightly packed collections of stars that orbit galaxies. The Milky Way contains about 150 of them, and each cluster may contain hundreds of thousands or even millions of stars. Although astronomers have studied globular clusters for more than a century, they still do not know exactly how these ancient stellar systems formed.
Studying their origins is difficult because the clusters we see today have already evolved for billions of years. Their original gas has disappeared, their largest stars have long since died, and their structures have changed over time.
One of the biggest clues comes from the unusual chemical makeup of stars inside many globular clusters. While the stars are roughly the same age, some contain unusually high levels of helium, nitrogen, sodium, and aluminum, while having relatively low amounts of carbon, oxygen, and magnesium. These chemical patterns require temperatures much hotter than those found inside even very massive ordinary stars.
According to the new model, repeated collisions between young stars in a crowded cluster could produce a single supermassive star hundreds of thousands of times more massive than the Sun. Although this giant star would live only briefly, it would act as an enormous nuclear furnace, creating the unusual chemical elements later found in the cluster’s stars. When the star died, it would release these newly formed elements into the surrounding gas, enriching the next generation of stars.
The idea is supported by several other observations. Little Red Dots appeared at roughly the same time astronomers believe the oldest globular clusters formed. Their numbers across the early universe also closely match the number of globular clusters seen today, and computer models suggest they could naturally evolve into the ancient star clusters that now surround galaxies.
The researchers stress that there is not yet definitive proof that Little Red Dots become globular clusters. However, they believe the new theory provides a simple explanation for several puzzling observations and should be considered alongside other ideas.
Future observations with the James Webb Space Telescope may help determine whether these mysterious red objects truly are the long-sought birthplace of the universe’s oldest star clusters.
