In an ancient galaxy, a record number of stars have been captured in photographs for the first time.

Studying individual stars in distant galaxies is incredibly challenging; however, scientists have successfully identified 44 stars in the ancient Dragon's Arc. Using the James Webb Space Telescope and gravitational lensing—a natural magnification effect caused by the strong gravitational fields of massive objects—astronomers were able to observe this galaxy as it existed 6.5 billion years ago. Until now, no one has been able to discover such a large number of individual stars in the relatively young universe.

2025-01-16 10:02:34https://naked-science.ru/article/astronomy/v-drevnej-galaktike-vperv

The study of the "childhood" and "youth" of the Universe (from the Big Bang to the formation of galaxies and stars) aids in understanding its evolution and sheds light on the fundamental physical laws that govern the structure and fate of the cosmos. Stars in ancient galaxies are of particular interest — until now, the study of "stellar populations" (that is, the number and types of stars) has only been possible in galaxies close to us, such as Andromeda or the Magellanic Clouds. More distant stellar treasures have remained beyond reach.

Everything changed with the launch of the James Webb Space Telescope: its high sensitivity and ability to capture faint light revealed that just 600 million years after the Big Bang, "developed" galaxies similar to modern ones had formed in the Universe. More about how this astronomical instrument has altered established views of the cosmos was previously discussed by Naked Science here.

Now, an international research team led by Fengwu Sun from the Harvard-Smithsonian Center for Astrophysics (USA) has, for the first time in history, examined 44 stars in the Dragon Arc galaxy, which formed when the Universe was roughly half its current age (13.8 billion years). However, had it not been for the massive galaxy cluster Abell 370 positioned between Earth and the Dragon Arc, the scientists would not have seen any celestial bodies.

The reason is that the Abell 370 cluster acted as a sort of "magnifying glass," amplifying the image captured by the James Webb Telescope: its gravity distorted the light so that the Dragon Arc stretched, resembling a long mirrored corridor. More precisely, this refers to the gravitational lensing effect predicted by Albert Einstein — a peculiar distortion of reality in the photographed space.

And that's not all: within the cluster itself, "rogue stars" were found — solitary celestial bodies "ejected" by gravity from their home galaxies, which, moving in front of the Dragon Arc, briefly enhanced the brightness of certain stars. This "double" amplification allowed the authors of the new study to record a record number of stars (observing one or two stars in such distant galaxies is a rare stroke of luck). The results of the scientific work were published in the journal Nature Astronomy.

Since the new celestial bodies were discovered during follow-up observations of the Dragon Arc (almost by chance), astronomers plan to search for similar phenomena in already studied areas, "catching" stars at moments of increased brightness using the James Webb Telescope. This approach will help understand what types of celestial bodies formed in the relatively young Universe, as well as compare the processes of star formation across different epochs.

The results of the new study demonstrated that examining a large number of stars in distant galaxies is now feasible. Furthermore, the high sensitivity of the James Webb Telescope, along with the powerful effect of gravitational lensing, may assist in the search for the mysterious dark matter that creates a gravitational field but is virtually unobservable in the electromagnetic spectrum. It is believed to exert gravitational influence on cosmic objects and affect the structure of galaxy clusters.