Webb telescope captures tantalizing evidence for mysterious 'dark stars'
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[July 18, 2023]
By Will Dunham
WASHINGTON (Reuters) - 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% 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 85% of the
universe's matter, with the remaining 15% comprising normal matter like
stars, planets, gas, dust and Earthly stuff like pizza and people.
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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.
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![](../images/071823PIX/news_n23.jpg)
These three objects were identified by
the James Webb Space Telescope Advanced Deep Extragalactic Survey
(JADES) in December 2022. They initially were identified as galaxies
that existed early in the universe’s history, but some scientists
suspect they are ”dark stars,” theoretical objects much bigger and
brighter than our sun, powered by particles of dark matter
annihilating themselves. NASA/ESA/Handout via REUTERS.
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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.
The three objects pegged as potential dark stars date to early in
the universe's history - one from 330 million years after the Big
Bang event that got the cosmos going 13.8 billion years ago, and the
others from 370 million years and 400 million years after the Big
Bang.
Based on the Webb data, these objects could be either early galaxies
or dark stars, Freese said.
"One supermassive dark star is as bright as an entire galaxy, so it
could be one or the other," Freese added.
While there is not enough data to make a definitive judgment about
these three, Freese said, Webb may be able to obtain fuller data on
other similarly primordial objects that could provide "smoking gun"
evidence of a dark star.
Conditions in the early universe may have been conducive to
formation of dark stars, with high dark matter densities at the
locations of star-forming clouds of hydrogen and helium. Such
conditions are highly unlikely today.
Freese and two colleagues first proposed the existence of dark stars
in 2008, basing the name on the 1960s Grateful Dead song "Dark
Star."
"It would be really super exciting to find a new type of star with a
new kind of heat source," Freese said. "It might lead to the first
dark matter particles being detected. And then you can learn about
the properties of dark matter particles by studying a variety of
dark stars of different masses."
(Reporting by Will Dunham, Editing by Rosalba O'Brien)
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