Using observations from the James Webb Space Telescope, astronomers found that at a time when the Universe was half its current age, a single galaxy behind the galaxy cluster Abel 370 had a redshift of 0.725 (Dragon We identified a star with more than 40 microlenses in an arc (called an arc).
In this Hubble image of Abell 370, the host galaxy in which 44 stars were discovered appears several times. Image credit: NASA.
“This groundbreaking discovery demonstrates for the first time that it is possible to study large numbers of individual stars in distant galaxies,” said Fengwu Sun, a postdoctoral researcher at the Harvard University & Smithsonian Center for Astrophysics. the doctor said.
“Previous studies using the NASA/ESA Hubble Space Telescope discovered about seven stars, and now we have the ability to resolve them in a way that was previously impossible. ”
“Importantly, observing larger numbers of individual stars will also help us better understand the dark matter in the lens surfaces of these galaxies and stars. i didn't understand.”
In the study, Sun and his colleagues analyzed web images of a galaxy known as Dragon Arc, which lies along the line of sight from Earth behind a massive galaxy cluster called Abel 370.
Through gravitational lensing, Abel 370 stretches the Dragon Arc's characteristic spiral into an elongated shape. It is a hall of mirrors as big as the universe.
Astronomers carefully analyzed the color of each star in the Dragon Arc and discovered that many of them were red supergiants. This is in contrast to previous discoveries that primarily identified blue supergiants.
The researchers say this difference in star types highlights the unique ability of Webb observations at infrared wavelengths to reveal stars even at low temperatures.
“When we discovered these individual stars, we were actually looking for background galaxies that were magnified by galaxies within this giant cluster,” Dr. Sun said.
“But when we processed the data, we found that there were many what appeared to be individual star points.”
“It was an exciting discovery because it was the first time we had been able to see so many individual stars so far away.”
“We know more about red supergiants in our local galactic neighborhood, because they are closer and we can take better images and spectra, and sometimes even break up stars. It’s from.”
“Knowledge gained from studying red supergiants in the local universe can be used in future studies to interpret what happens next to red supergiants during the early stages of galaxy formation.”
Most galaxies, including the Milky Way, contain tens of billions of stars. In nearby galaxies, such as the Andromeda galaxy, astronomers can observe stars one by one.
But in galaxies that are billions of light years away, their light has to travel billions of light years to reach us, so stars appear mixed together, which explains how galaxies form and evolve. This has been a long-standing challenge for scientists who study it.
“To us, very distant galaxies usually look like diffuse, blurry clumps,” says Dr. Yoshinobu Fudamoto, an astronomer at Chiba University.
“But in reality, those clumps are made up of so many individual stars that our telescopes can't resolve them.”
of findings Published in a magazine natural astronomy.
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Yuya Fudamoto others. Identified over 40 gravitationally expanded stars in the galaxy at redshift 0.725. Nat Astronpublished online on January 6, 2025. doi: 10.1038/s41550-024-02432-3
Source: www.sci.news
