2024-03-22 05:57:28
Scientists have discovered one of the oldest stars, which was formed in another galaxy, BTA reported, citing the electronic publication “Iuricolort”.
“This star is a unique window into the very early process of element formation in galaxies other than our own,” said Anirudh Chitty of the University of Chicago, lead author of a paper announcing the discovery. It was published in the journal Nature Astronomers.
“We have an idea of what stars look like that were chemically enriched by the first stars in the Milky Way, but we still don’t know if some of these signatures are unique or if things have happened in a similar way in other galaxies,” he notes.
The first generation of stars transformed the universe. In their cores, ordinary hydrogen and helium fuse into a rainbow of elements. When these stars die, they explode and new elements are scattered throughout the universe. The iron that flows in the veins of people, the calcium in the teeth and the sodium that supports our thinking were born in the heart of a long-dead star, recalls “Urikalert”.
No one has been able to find any of these first-generation stars, but scientists at the University of Chicago have announced a unique find: a second-generation star that originally formed in a galaxy other than our own.
The lead author of the study, Anirudh Chitti, specializes in the so-called stellar archaeology: reconstructing how the earliest generations of stars changed the universe. “We want to understand what the properties of the first stars were and what elements they produced,” explains the researcher.
No one has yet been able to directly see these first-generation stars, if they exist at all in the universe. Instead, Chitti and his colleagues are looking for ones formed from the ashes of that first generation.
This is a difficult task because even the second generation of stars are now very old and rare. Most such bodies in the universe, including the Sun, are the result of tens to thousands of generations, each time accumulating more and more heavy elements. “Maybe less than one in 100,000 stars in the Milky Way is second-generation,” he says. “We are really looking for needles in haystacks”.
But it’s worth getting snapshots of what the universe looked like back in time, experts say. “In their outer layers, these stars retain the elements from where they formed,” explains Chitti. “If you can find a very old star and get its chemical composition, you can understand what the chemical composition of the universe was where that star formed billions of years ago,” he added.
For the purpose of the study, Chitti and his colleagues pointed telescopes at an unusual target: the stars that make up the Large Magellanic Cloud, a bright strip of stars visible to the naked eye in the Southern Hemisphere. It is believed that it was once a separate galaxy, attracted by the gravity of the Milky Way just a few billion years ago, notes Euricalert.
Scientists are looking for evidence of very old stars there and have cataloged ten of them – first with the European Space Agency’s Gaia telescope and then with Magellan, which is located in Chile.
One of these stars immediately stands out as an oddity. It has significantly fewer heavy elements than any other star observed so far in the Large Magellanic Cloud. That means it probably formed after the first generation of stars — so it hasn’t yet accumulated heavier elements over the course of repeated births and deaths of stars, the paper said.
Mapping its elements, scientists were surprised to find that the star has much less carbon than iron, compared to what is seen in stars in the Milky Way.
“This was very intriguing and suggests that perhaps the increase in carbon in the earliest generation, as we see in the Milky Way, was not universal,” says researcher Chitti. “We’ll need to do more research, but this gives us reason to believe there are differences between sites.”
According to him, “we complete the picture of what the process of enrichment of early elements looked like in a different environment”.
The findings also confirm other research that suggests the Large Magellanic Cloud formed far fewer stars early on than the Milky Way.
“It’s really exciting to discover the stellar archeology of the Large Magellanic Cloud and to be able to map in such detail how the first stars chemically enriched the universe in different regions,” added Chitti of the University of Chicago.