Webb's little red dots may be stars with black holes in their belliesBlack Holes or Black Hole Stars? Astronomers Spar Over Webb Telescope’s ‘Little Red Dots.’

The Webb telescope stares at faint light from the universe's first billion years and keeps catching something odd: tiny, red, one pixel across, yet as bright as an entire galaxy. A couple turn up in almost every image.

In 2023 astronomers named them little red dots.

First 'universe breakers', then black holes

At first people assumed they were distant galaxies. But a galaxy that bright would have to be absurdly large, and the universe had barely any time to grow one — so they were dubbed 'universe breakers', as if they were tearing up the standard cosmic timetable.

Then detailed colour breakdowns, known as spectra, showed the hydrogen colours smeared into a broad band. That is the signature of gas whipping around a black hole at enormous speed. The mainstream view shifted: little red dots are the supermassive black holes of the early universe.

Spring 2025: the two reddest dots

Two dots were freakishly red. Almost no light at the blue end, then a sudden jump at one particular red shade. This cliff, called a Balmer break, normally appears over a hot ball of hydrogen — a stellar surface.

But a star cannot be that bright, and a black hole does not produce that smooth red hump. Two teams independently concluded they were looking at something new: a black hole star.

Outside, a vast shell of hydrogen, reaching a dozen times further out than Pluto's orbit. Inside, a black hole acting as the engine, the way fusion powers our sun. The shell would also block X-rays, explaining why other red dots neither flicker nor glow in X-rays.

The other camp: ordinary black holes will do

Roberto Maiolino at Cambridge rebuts each point. No flicker? Early black holes may have eaten more steadily. No X-rays? The thick doughnut of gas and dust around a normal black hole blocks most of them anyway.

He also argues the redness depends on the viewing angle: the reddest dots are simply the ones we see edge-on, their doughnut in the way. He and a collaborator invoke Occam's razor — if black holes explain it, why invent a new species?

By 2026 both theories still fit what Webb has seen. Anna-Christina Eilers at MIT says the field has become thoroughly polarised.

A ghost from 2006 comes back

Mitchell Begelman at the University of Colorado was lecturing on little red dots when he recognised an old idea of his own: the quasi-star, proposed in 2006. A huge gas cloud collapses at the centre straight into a black hole, with the rest of the cloud wrapped around it. In 2026 a team found the model fits the spectra of those two red dots even better than the first version did.

One more clue favours the camp: if little red dots are the infancy of black hole stars, they should grow rarer over time. An August 2026 census found exactly that — by the time the universe reached two or three billion years old, the dots had mostly vanished.

Others suspect both sides are right.

In one line: the young universe may really have raised giant stars with black holes in their bellies — or old black holes may simply be showing us their bad side. Either way, the argument is still going.