By all rights, they shouldn’t exist.

When NASA’s James Webb Space Telescope (JWST) first opened its eyes to the distant past, it spotted hundreds of tiny, brilliant objects glowing red in the infant universe — just 600 million years after the Big Bang. These “little red dots,” as astronomers came to call them, gleamed with such surprising brightness and density that they seemed to defy the basic rules of cosmology.

“It’s like finding a toddler who is six feet tall,” said Anthony Taylor, a postdoctoral researcher at the University of Texas at Austin.

At first, astronomers suspected they were looking at early, unusually compact galaxies. But further observations failed to match that idea. The dots were too small, too red, and too luminous. They didn’t fit any known category of star or galaxy.

Now, after months of mounting evidence, researchers are considering a radical new explanation. The little red dots might be an entirely new kind of cosmic object: black hole stars.

A Black Hole Wrapped in Fire

The idea goes like this: each dot is a massive cocoon of hot gas — larger than our solar system — that glows like a star. But instead of being powered by nuclear fusion, like regular stars, these objects shine because of the immense heat generated by a black hole hidden within.

“Basically, the gas is opaque and so it radiates like a star,” explained Jenny Greene, an astrophysicist at Princeton University, in an interview with Science Mag.

The concept of a “black hole star” is not entirely new. Theoretical physicist Mitch Begelman and colleagues first proposed it two decades ago under the name quasi-star. In that model, a giant star forms early in the universe, then collapses into a black hole. The black hole, instead of blowing away its outer layers, becomes shrouded in them. It keeps growing, heating the envelope of gas from within — turning the entire object into a single, swollen, glowing sphere.

“That’s what the quasi-star envelope is doing,” Begelman told Science. “It’s force-feeding the black hole by pushing matter into it.”

Not Dust, Not Galaxies, Not Stars

The little red dots, or LRDs, first appeared in data from JWST’s early deep-sky surveys. Since then, researchers have found around 340 of them across multiple programs, including the Advanced Deep Extragalactic Survey and the RUBIES survey. Each one is incredibly compact — often no wider than 500 light-years — and incredibly luminous, sometimes rivaling the brightness of a full-sized galaxy.

“If you look at a very bright object in the early universe and assume it’s all stars, it comes out looking extraordinarily massive — almost too massive to have assembled in the age of the universe up to that time,” Taylor told Symmetry Magazine.

Initially, some scientists thought these might be galaxies full of aging stars, or obscured by dust. Dust, after all, can block ultraviolet and X-ray radiation and re-emit it as redder light, explaining both their color and dim X-ray signature.

But this idea fell apart earlier this year. Using the Atacama Large Millimeter/submillimeter Array (ALMA) and JWST’s own mid-infrared instruments, astronomers searched for signs of dust in and around dozens of LRDs. They found none.

“They’re not dusty,” said Greene. “What we’re seeing is really the light that’s coming from this thing, whatever it is.”

The spectral data only deepened the mystery. When astronomers broke down the light from these objects, they found the distinctive emission lines of hydrogen gas heated to extreme temperatures — exactly the kind of signal seen around active black holes. But oddly, there were also features typical of stellar atmospheres, like absorption lines and a red peak. One researcher described their spectral profile as “V-shaped,” sloping down in the ultraviolet and rising again in the optical.

“Very quickly a whole bunch of peculiarities began to emerge which showed that these are really nothing like any class of object that we really knew,” said Rohan Naidu of MIT.

Growing Monsters in a Hurry

The deeper puzzle goes beyond what these objects are. It’s what they become.

Most large galaxies today — including the Milky Way — harbor supermassive black holes in their centers. But how these giants formed in just a few billion years remains an open question. One theory says they grew from small stellar black holes that merged and accreted material over time. Another posits the rapid birth of much larger “seed” black holes from events like direct gas collapse or quasi-stars.

The little red dots seem to support the latter.

If more evidence confirms that LRDs harbor accreting black holes, they could represent the formative phase of the supermassive black holes now scattered across the universe.

In some cases, researchers estimate that the black hole inside an LRD might account for 10% to 50% of the object’s total mass. That’s wildly different from local galaxies, where the black hole usually weighs in at just 0.1% of the host galaxy’s mass.

“Either they’re very little black holes that are making copious amounts of light, or we’re growing the black hole mass way faster than we ever thought before,” said Greene. “Both of those are really exciting and interesting in different ways.”

Unfinished Answers, Accelerating Questions

Despite the excitement, scientists are still cautious. There’s no direct proof yet that black holes sit at the heart of every little red dot. The absence of X-rays, typically emitted by accreting black holes, remains a major puzzle.

Many LRDs also show signs of features commonly associated with old stars, such as absorption lines and Balmer breaks — a sudden dip in light at certain wavelengths. But some researchers think the turbulent, dense gas around a black hole could mimic these same spectral traits.

“It tells us they are the progenitors of some other population,” said Akins. “Then they evolve and become something else.”

And for now, little red dots seem to be a phenomenon frozen in time. They appeared in a narrow slice of cosmic history — between 600 million and 1.5 billion years after the Big Bang — and then disappeared. They don’t show up in today’s universe.

That might be about to change. A team led by Xiaojing Lin of Tsinghua University recently reported several LRD-like objects just 2.5 billion light-years away. These closer examples may give astronomers a better shot at resolving their internal structure.

Lin’s team has secured time on the Hubble Space Telescope to look for signs of interactions — outflows, inflows, and other disturbances — that might reveal how a black hole star operates.

Meanwhile, the astronomy community is preparing for a flood of new JWST data. Many of the telescope’s fourth-cycle observation programs, which began in July, will focus on little red dots. Some teams will search for short-term variations in brightness — a smoking gun for black holes. Others will hunt for the telltale signs of stellar aging.

The field is still wide open. But the mystery, once a blur, is sharpening.

And if the Milky Way itself was once a little red dot? “I can totally imagine that,” Greene added, “and then it kind of piddled along for the rest of cosmic time.