Primordial stars found to contain few elements heavier than hydrogen or helium could be direct descendants of one of the first stars in the universe.
if star If they were like myths, the first generation of stars that existed in the universe would be like the gods of ancient Greece. It was huge and mysterious, and would have had a huge influence on the stars that followed.
But no one has ever seen these first stars, “either because they were huge, lived fast and died young, or because the lowest-mass Population III stars that are likely to survive into the present day are extremely rare,” said Kevin Schlafman of Johns Hopkins University. statement.
Therefore, we have not yet seen a population III star, but a star called SDSS J0715-7334 is the next best star. The star was formed from a nearly pristine cloud of gas that was contaminated by heavy elements formed on Earth. supernova Population III star explosion.
SDSS J0715-7334 was first identified by Schlaufman in Sloan Digital Sky Survey data in 2014, and then independently discovered in 2025 by a team of students led by Alexander Ji at the University of Chicago.
In the first 3 minutes after starting big bangOnly three elements were present: , hydrogen, helium, and trace amounts of lithium. That’s all the universe needed to do to form its first stars. Everything else element Stars on the periodic table had to be formed by subsequent stars, starting with the supernova explosions of the most massive Group 3 stars.
Heavy elements produced in the traumatic death of one first-generation star rapidly contaminated a primordial cloud of hydrogen and helium molecules, which then collapsed to form SDSS J0715-7334. This is thought to have happened during the first few hundred million years after the Big Bang.
Using the high-resolution Magellan Inamori-Kyocera Echelle spectrometer on the 6.5-meter Magellan Clay Telescope at Chile’s Las Campanas Observatory, Ji and Schlafman’s team followed up on SDSS J0715-7334 to quantify the abundance of heavy elements, which astronomers call “metals.” Heavy elements include elements such as carbon and oxygen in addition to aluminum and iron.
Our Sun is made of 74.9% hydrogen, 23.8% helium, and 1.3% metals, representing generations of stars over cosmic time that have accumulated an abundance of heavy elements in the universe. Meanwhile, Ji and Schlaufman’s team found that SDSS J0715-7334 is made up almost exclusively of hydrogen and helium, making up only 0.005% of the metals found in the Sun. No other star has been found that is so pure and has so few heavy elements. Previous record holder, our star milky way This material, cataloged as SDSS J1029+1729, is twice as rich in heavy elements as SDSS J0715-7334.
“Star [SDSS J0715-7334] “The carbon content is so low that it suggests that early sprinkled cosmic dust is responsible for carbon production,” Gee said in a separate article. statement.
“Although this star itself does not have a pristine composition, it is the closest astronomers have ever come to the generation of Population III stars by this particular criterion,” Schlaufman added.
Ji and Schlafman’s team were able to work backwards from its chemical composition to estimate the star’s mass and the energy of the supernova that produced the debris that contaminated SDSS J0715-7334’s birth cloud. They found that the deceased Population III star had at least 30 times the mass of the Sun, and its supernova explosion was more energetic than typical today.
80,000 SDSS J0715-7334 found light year Farther away, it appears to be moving from the outer halo. large magellanic cloud (LMC), that’s why Ji’s students called this star “ancient immigrant”.
With his friends, small magellanic cloudthe LMC is a recent arrival on the shores of the Milky Way, and for most of its history, the Magellanic Cloud formed stars and did not accumulate an inventory of chemicals. It wasn’t until they approached the Milky Way’s gravitational influence that things really started to move inside them.
“It’s possible that a relatively higher proportion of supermetal-poor stars can be found in galaxies like the Magellanic Clouds than in our own Milky Way galaxy,” Schlaufman said.
The Sloan Digital Sky Survey is an excellent tool for tracking ancient, pristine stars such as SDSS J0715-7334. Located at the Apache Point Observatory in New Mexico, it conducts extensive surveys of the night sky, making optical and infrared spectroscopic measurements of millions of stars and galaxies.
“We still have a lot of work to do to understand what was actually going on in the distant past, when the Milky Way was young,” Schlafman said. “At this stage of the Sloan Digital Sky Survey, we have only scratched the surface.”
The study was published in the April 3 issue. natural astronomy.
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