44 individual stars discovered in a galaxy billions of light years away
Luck has recently led to the discovery of several individual stars in extremely distant galaxies. 44 in a single galaxy, though, is a novelty.
The "dragon arch" (bottom center)
(Image: NASA)
Thanks to a gigantic gravitational lens, an international research team has succeeded in identifying several dozen individual stars in a galaxy 6.5 billion light years away. The record find includes the largest number of individual stars in the distant universe, explains the University of Arizona. In total, there are 44 individual celestial bodies. Their brightness changes over time, which the research team attributes to changes in the gravitational lens that focuses the light of the objects behind them so that we can see them in the first place. The proof was therefore provided by two images taken by the James Webb Space Telescope.
Only isolated findings so far
The fact that individual stars can be detected at all in galaxies billions of light years away is a fairly new development. Until now, however, even with the best technology, such record finds were limited to individual stars in entire galaxies, the best known being the star “Earendel” (“morning star” in Old English) discovered in 2022. It is only visible because its galaxy “Sunrise Arc” is greatly magnified by enormously massive objects in the foreground. By a lucky coincidence, however, Earendel itself is magnified by a factor of 4,000. The discovery now presented is based on similar circumstances, only here several dozen stars can be seen individually.
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All 44 stars that have now been discovered are located in a galaxy known as the “Dragon Arc”. Their light is bundled by the galaxy cluster Abell 370 in front of them in such a way that their image is greatly elongated. The James Webb Space Telescope focused on this arc in December 2022 and one year later. Astronomer Fengwu Sun discovered the individual stars in these images. The groundbreaking discovery shows for the first time that the analysis of many stars in distant galaxies is possible in principle, he adds.
(Image:Â Fudamotot et.al)
However, the discovery is based on another fortunate circumstance. The university explains that many stars in the galaxy cluster are traveling unbound and magnify individual stars in the background like a kind of microlens. However, because they are moving, they repeatedly highlight other stars over the course of time, which therefore only become detectable temporarily and then disappear again. The team therefore expects hundreds of individual stars in these distant galaxies to come into focus on further images. Most of those now discovered are therefore red supergiants – i.e., not even of the brightest star class. The work is now being presented in the scientific journal Nature Astronomy.
(mho)
