Astronomers believe they may have detected the last remnants of one of the first stars in the universe using a Maunakea telescope.
According to a report from the National Science Foundation’s astronomy research center NOIRLab, researchers using the Gemini North telescope on Maunakea analyzed a cloud of material in a distant galaxy and determined that it could be the remains of a long-destroyed star that could have formed during the first 100 million years of the universe.
NOIRLab associate scientist Vinicius Placco said the oldest stars in the cosmos are referred to as Population III stars and have never been directly observed.
“Most of the speculation about Population III stars is that most would be huge and would have evolved rapidly in the few million years after the Big Bang,” Placco said. “They would be formed just out of hydrogen and helium, because anything heavier than hydrogen and helium didn’t exist yet.”
Because of the presumed mass of Population III stars, Placco said most astronomers assume they are all so long-dead that they will never be observed directly. But by using the Gemini Near-Infrared Spectrograph, a team of researchers from the University of Tokyo and the University of Notre Dame determined that a cloud of matter that formed around a distant quasar most closely matches the hypothesized composition of a Population III star about 300 times the mass of the sun.
The cloud was determined to have a curiously high amount of iron, which Placco said is almost impossible for an object that formed so early in the universe. The only known process that could have produced so much iron so early in the universe, he said, is a Population III star.
“Population III stars are the furnaces that make all the elements of the periodic table,” Placco said, explaining that, as Population III stars age, they start forming heavier elements within their cores and release them into space. Ultimately, all elements in the universe heavier than hydrogen and helium originate from stars.
This particular star is believed to have been destroyed in an unusual pair-instability supernova, a “super-supernova” caused by a runaway thermonuclear reaction that completely obliterates the star.
While typical supernovas leave behind some part of the star’s core — which can form a white dwarf or a black hole, depending on the star’s mass — Placco said pair-instability supernovas leave no part of the core behind, and can only be inferred to have happened by finding the stellar material scattered by the explosion.
Placco said the discovery provides valuable insight into the early years of the universe.
“We wanted to know the nature of the first stars,” Placco said. “If you can figure out the nature and distribution of these stars, you can figure out the chemical evolution of the entire universe.”
Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.
