Black Hole Stars

We may finally have an explanation for the strange red dots observed in the early universe. They could be black hole stars.

The James Webb Space Telescope was designed to give us an unprecedented view of the very early universe. When it began operating two years ago, it surprised astronomers by revealing mysterious red dots dating from less than two billion years after the Big Bang, which occurred approximately 13.7 billion years ago.

At first, some scientists speculated that these objects might be unusually mature spiral galaxies, perhaps resembling our own Milky Way. But it would be rather strange for galaxies to have become so evolved so early in cosmic history.

After astronomers discovered one particularly dense red dot, nicknamed the Cliff, a different explanation emerged: these objects could be black hole stars. These are objects that had been predicted theoretically but had never previously been observed in nature. They are enormous balls of relatively cool gas containing a gigantic supermassive black hole that is steadily accumulating mass within them.

Ordinary stars shine because nuclear fusion takes place in their interiors. Black hole stars, on the other hand, are powered by the black hole at their centre. Their outer layers are not as bright as those of ordinary stars and have much lower temperatures, more similar to those of red dwarf stars.

Red dwarfs are the least massive ordinary stars in which nuclear fusion of the most common isotope of hydrogen, containing just one proton and known as protium, can take place. This is why these mysterious ancient objects appear red.

The discovery of black hole stars could finally help us understand how supermassive black holes managed to grow so enormously massive so quickly in the early universe.