Astronomers may have discovered an entirely new kind of object in the early universe: something that looks like an enormous star but is powered by a massive black hole hidden inside it.
Researchers from MIT and other institutions spotted the mysterious object using NASA’s James Webb Space Telescope (JWST). It appears as an extremely bright red dot from a time just a few hundred million years after the Big Bang.
At first glance, the object resembles a gigantic star roughly the size of our solar system. But there is a major problem with that explanation. It appears to produce about 100 billion times more energy than any normal star could physically generate.
Instead, the researchers think they may be seeing a previously unknown object that combines features of a star and a black hole. They have given it the striking name “black hole star.”
The discovery, reported in Nature, could also help explain one of the biggest mysteries created by JWST.
Since the telescope began exploring the distant universe, astronomers have repeatedly found mysterious objects known as “little red dots.” They were common when the universe was young but appear to have largely vanished later in cosmic history.
The newly discovered object, called MoM-BH*-1, may offer an important clue to what these red dots actually are.
The researchers estimate that MoM-BH*-1 contains a black hole around 100,000 times the mass of the sun. Surrounding it is an enormous, extremely dense cloud of hydrogen gas that stretches roughly across the size of our solar system.
From the outside, this thick gas envelope behaves somewhat like the atmosphere of an enormous star. But unlike an ordinary star, its tremendous energy does not come from nuclear fusion. Instead, the central black hole appears to provide the power as material falls toward it.
The discovery was unexpected. The team had been searching for some of the earliest galaxies as part of a project called “Mirage or Miracle.” While examining JWST observations, they noticed one particularly bright and red object.
Astronomers often assume that extremely red objects are surrounded by large amounts of dust. Dust can absorb and scatter light, making distant objects appear redder. But the light from MoM-BH*-1 did not behave as expected for a dusty galaxy.
Instead, researchers found a dramatic drop in light below certain wavelengths, known as a Balmer break. This feature is commonly associated with dense gas in stellar atmospheres. The break in MoM-BH*-1 was more extreme than anything the researchers had previously observed.
Its light also showed almost no evidence of heavier elements, or “metals,” containing mainly signatures of hydrogen and helium.
Computer simulations provided another clue. The researchers found that an incredibly dense envelope of hydrogen surrounding a powerful energy source could reproduce the unusual light pattern. However, ordinary nuclear fusion could never explain the object’s extraordinary brightness.
Adding a growing black hole to their simulations produced a much better match.
The researchers now suspect that similar black hole stars could explain many of the little red dots found throughout JWST images. MoM-BH*-1 may simply be an especially dramatic example because its black hole-powered light is so intense that it overwhelms the surrounding galaxy.
If confirmed, these strange objects could provide a new window into the early universe and potentially help astronomers understand how massive black holes formed and grew so quickly after the Big Bang.
