One of the biggest mysteries revealed by the James Webb Space Telescope may finally have a promising explanation.
Astronomers believe that the strange objects known as “little red dots” could be enormous stars unlike anything seen in the universe today.
These giant stars may also have been the seeds that eventually grew into the first supermassive black holes.
The new research, led by scientists at the Harvard College Observatory, suggests that these unusual stars can explain many of the puzzling features of the little red dots all at once.
The findings were published in The Astrophysical Journal Letters.
The little red dots are tiny, bright, reddish objects that appeared when the universe was less than one billion years old. Since the James Webb Space Telescope first spotted them, astronomers have debated what they really are.
Some thought they might be young galaxies, while others suggested they were rapidly growing black holes, powerful bursts of star formation, or even a completely new type of cosmic object.
The problem is that none of these ideas fully matches what the telescope has observed.
The light coming from the little red dots contains unusual patterns of hydrogen that do not fit current models of young galaxies or active black holes. At the same time, most of these objects do not produce the strong X-rays or radio waves that scientists normally expect from black holes feeding on surrounding material.
This has left researchers searching for another explanation.
The new study points to supermassive stars, incredible objects that may have been around 100,000 times more massive than our Sun. Earlier research by the same team showed that stars this large could naturally produce the unusual hydrogen signatures seen in the little red dots.
In their latest work, the researchers looked at another mystery: why these objects appear so small and compact in James Webb images.
Using computer models, they followed the lives of these giant stars from birth to death. They discovered that, unlike many ordinary stars, supermassive stars do not steadily lose material as they age. Instead, they experience rare but violent pulsations that suddenly throw huge shells of gas into space. The researchers call these events “strange-mode” pulsations.
These expanding shells of gas form a dense cocoon around the star. The cocoon traps and reshapes the star’s light, making the object appear compact and creating many of the unusual features seen by James Webb.
The models also revealed that the gas released during these eruptions is rich in hydrogen, helium, and nitrogen. Interestingly, astronomers are beginning to detect nitrogen-rich light from some little red dots, providing another piece of evidence that supports the giant-star theory.
Eventually, after these powerful eruptions end, the supermassive star is expected to collapse directly under its own gravity. Instead of exploding like a normal supernova, it would form the seed of a supermassive black hole.
If this idea is correct, the mysterious little red dots may represent a brief stage in cosmic history when enormous stars were transforming into the first giant black holes.
The research team now plans to make more detailed predictions about what these stars should look like so future observations from the James Webb Space Telescope can test whether this exciting explanation is correct.
Source: KSR.
