Study finds ‘dark stars’

By By Carlos Mayorga

By Carlos Mayorga

It is possible that the first stars in the universe did not shine.

According to a recent U study, invisible dark stars could have formed 13 billion years ago from the presence of dark matter. Dark matter is still unseen and unidentified, but scientists believe that it makes up most of the universe.

The findings, which will be published next month in the journal Physical Review Letters, could “change our understanding of the formation of stars in the universe,” said Paolo Gondolo, a professor in the department of physics.

The discovery of these dark stars would represent a new phase in how scientists believe stars evolved. Traditionally, scientists agree all stars in the universe are formed when clouds of hydrogen and helium come together and create a nuclear fusion. This fusion makes regular stars shine.

But the study concludes that dark stars also exist. Dark stars appear dark because they do not emit visible light — they glow in the infrared spectrum, which is heat that humans don’t see radiating, Gondolo said.

These colossal dark stars, which can be 400 to 200,000 times wider than the sun, are detectable today through infrared technology, but questions still linger about exactly how they look, Gondolo said. Scientists plan to observe these stars in more detail once the U opens an infrared observatory in southern Utah.

Discovery of these black stars could help astrophysicists find answers to other mysteries about the universe, such as how some black holes are formed.

Black holes — collapsed stars that are so dense that not even light can escape — are formed slowly over a minimum of 100 million years. But scientists have found that some black holes were formed only 10 million years after the “big bang,” which is when scientists believe the universe was created.

“Perhaps one of these dark stars could have collapsed and formed a black hole, but we still don’t know,” said Douglas Spolyar, a graduate student at the University of California, Santa Cruz who helped conduct the study.

The study, funded by the National Science Foundation, the U.S. Department of Energy and the University of Michigan, could also lead to better insight of how stars evolve, how to identify dark matter and how to improve understanding of how heavy elements are formed. Astrophysicist Katherine Freese from the University of Michigan, Ann Arbor also contributed to the study.

Gondolo said he originally wanted to call the dark stars “brown giants,” which would make their name similar to smaller stars known as “brown dwarfs,” but the co-authors insisted they be named dark stars after the song “Dark Star” by the rock band The Grateful Dead.

“I prefer brown giant because the stars really glow with the infrared,” Gondolo said. “But ‘dark star’ is catchier.”

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Infrared was integral in finding dark stars.