SPACE — The James Webb Telescope may have discovered an ancient star powered by dark matter. By scientists, this star is called a dark star.
Reporting from BBC Sky at Night, dark stars are candidates for the first stars to form in the universe. This star existed about two hundred million years after the Big Bang. These stars are only made of hydrogen and helium produced from the Big Bang.
Unlike stars that are powered by nuclear fusion, these stars will be powered by dark matter. Because there is no fusion taking place in it, the temperature is not too hot. However, dark stars can grow to reach perhaps a million times the mass of the Sun and a billion times the brightness.
How do dark stars form?
Katherine Freese, director of the Weinberg Institute for Theoretical Physics, said the first stars formed in environments rich in dark matter. Stars formed in the centers of early proto-galaxies.
Here, hydrogen clouds are beginning to collapse into fusion-powered stars but are in large clusters of dark matter.
“We found that after a series of reactions, dark matter particles can annihilate each other and most end up as photons and other particles,” he said.
These photons can get trapped in collapsing gas clouds and dump all the energy previously contained in dark matter into them. This is a source of energy large enough to turn collapsing clouds into stars.
Even though it is called a dark star, this star is actually not dark at all. In fact, the star’s mass is only about 0.1 percent that of dark matter.
How can a star be bright yet cool?
The brightness of a star is related to the star’s radius and temperature. Although the temperature of dark stars is almost the same as the surface temperature of the Sun, the radius of these stars is so large that they can be very bright.
Dark stars can live as long as they have dark matter fuel. Dark stars, he said, can last millions to billions of years.
But if a dark star moves away from a dark matter-rich environment, it will begin to collapse. As it collapses, the star will heat up.
For large dark stars that have a mass about a million times greater than the Sun, their collapse will form a black hole.
2023-12-01 09:16:00
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