Webb telescope captures tantalising evidence for mysterious ‘dark stars’

WASHINGTON: Scientists for the past 15 years have been looking for evidence of a type of star only hypothesized but never observed — one powered not by the fusion of atoms like the sun and other ordinary stars but by mysterious stuff called dark matter.

Thanks to the James Webb Space Telescope’s ability to peer back to the dawn of the universe, the first good candidates to be “dark stars” have been identified.

The three objects spotted by Webb, which was launched in 2021 and began collecting data last year, were initially identified last December as some of the universe’s earliest-known galaxies but, according to researchers, instead might actually be humongous dark stars.

Dark matter, invisible material whose presence is known mainly based on its gravitational effects at a galactic scale, would be a small but crucial ingredient in dark stars. These stars are described as made almost entirely of hydrogen and helium — the two elements present during the universe’s infancy — with 0.1 per cent of their mass in the form of dark matter. But self-annihilating dark matter would be their engine.

Dark matter is invisible to us — it does not produce or directly interact with light — but is thought to account for about 85pc of the universe’s matter, with the remaining 15pc comprising normal matter like stars, planets, gas, dust and Earthly stuff like pizza and people.

Dark stars would be able to achieve a mass at least a million times greater than the sun and a luminosity at least a billion times greater, with a diameter roughly ten times the distance between Earth and the sun.

“They’re big puffy beasts,” said Katherine Freese, a theoretical astrophysicist at the University of Texas at Austin and senior author of the research published in the journal Proceedings of the National Academy of Sciences.

“They are made of atomic matter and powered by the little bit of dark matter that’s inside them,” Freese added. Unlike ordinary stars, they would be able to gain mass by accumulating gas falling into them in space.

“They can continue to accrete the surrounding gas almost indefinitely, reaching supermassive status,” said Colgate University astrophysicist and study lead author Cosmin Ilie.

They would not have been as hot as the universe’s first generation of ordinary stars. It was the nuclear fusion occurring in the cores of those stars that spawned elements heavier than hydrogen and helium.