COSMOS MAGAZINE

Dragon Arc galaxy pictured in extraordinary detail

Words by Ellen Phiddian

Astronomers have used a trick of gravity and the James Webb Space Telescope (JWST) to picture 44 individual stars in a galaxy 6.5 billion light-years away.

Credit: NASA

Abell 370, a galaxy cluster located nearly 4 billion light-years away from Earth. The Dragon Arc is in the lower left of centre. These arcs are caused by gravitational lensing: Light from even more distant galaxies is bent around the massive gravity of Abell 370. Credit: NASA

The galaxy, dubbed the Dragon Arc, hails from a time when the Universe was half its current age. The observation, which uses a technique called gravitational lensing, marks the largest number of individual stars seen in the distant Universe.

Credit: NASA

Yoshinobu Fudamoto, assistant professor at Chiba University in Japan

“To us, galaxies that are very far away usually look like a diffuse, fuzzy blob. But actually, those blobs consist of many, many individual stars. We just can’t resolve them with our telescopes.”

Instead, the team used the laws of physics.  Very massive objects, like galactic clusters, cause a natural magnification with their strong gravitational fields. This is gravitational lensing. The JWST is sensitive enough to use gravitational lensing to see super-distant objects.

Credit: Yoshinobu Fudamoto

The team found that many of the stars they identified were red supergiants, at the end of their lives.

Credit: NASA

“This groundbreaking discovery demonstrates, for the first time, that studying large numbers of individual stars in a distant galaxy is possible,” says co-author Fengwu Sun, postdoctoral scholar at the Harvard & Smithsonian Center for Astrophysics.

cosmosmagazine.com 

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