The type of stars found in the universe has changed over time. When stars run out of fuel and explode as supernovae, the heavier elements are spread around and incorporated into the next generation of stars. Astronomers refer to stars' metallicity because they gained higher levels of heavier elements.
If you could look back at the very earliest stars, they would be very different from today's stars. One of the holy grails of astronomy research is searching for the Population III stars, formed when the universe was less than 100 million years old.
The debris from these stars may have been identified for the first time. The researchers looked at a distant quasar and saw the chemical composition of the clouds around it. The composition had a high ratio of iron to magnesium. The material could have been created from an event called a pair-instability supernova. These low-metallicity stars could be affected by a theoretical type of supernova.
Researchers were able to identify material from early stars by looking for the remnants of special supernovae. The supernova candidate for this would be a pair-instability supernova of a Population III star, in which the entire star explodes without leaving any remnant behind. A pair-instability supernova of a star with a mass about 300 times that of the Sun provides a ratio of magnesium to iron that matches the low value we derived for the quasar.
If we were to search for more of the remnants of early stars, we could learn more about how the universe ended up. Co-author Timothy Beers of the University of Notre Dame said that they now know what to look for. We would expect to find evidence for this if it happened in the very early Universe.
The research is in a journal.
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