The researchers studied the Sparkler galaxy located in Webb’s First Deep Field and used JWST to determine that five of the sparkling objects around it are globular clusters. Credit: Canadian Space Agency with images from NASA, ESA, CSA, STScI; Mowla, Iyer et al. 2022
Key Points:
- Early analysis of Webb’s First Deep Field image indicates researchers captured some of the universe’s earliest galaxies.
- The “Sparkler Galaxy” is 9 billion light years away and is determined to contain globular clusters, or ancient collections of stars.
- Using very distant globular clusters to age-date the first stars in distant galaxies has not been done before and is only possible with Webb.
A Canadian research team using the James Webb Space Telescope has identified the most distant globular clusters ever discovered. These dense groups of millions of stars may be relics that contain the first and oldest stars in the universe.
In the finely detailed Webb’s First Deep Field image, the researchers zeroed in on what they’ve dubbed “the Sparkler galaxy,” which is 9 billion light years away. This galaxy got its name for the compact objects appearing as small yellow-red dots surrounding it—or the “sparkles.” The team posited that these sparkles could either be young clusters actively forming stars—born 3 billion years after the Big Bang at the peak of star formation—or old globular clusters. Globular clusters are ancient collections of stars from a galaxy’s infancy and contain clues about its earliest phases of formation and growth.
From their initial analysis of 12 of these compact objects, the researchers determined that five of them are not only globular clusters but among the oldest ones known.
The Milky Way galaxy has about 150 globular clusters, and how and when exactly these dense clumps of stars formed is not well understood. Astronomers know that globular clusters can be extremely old, but it is incredibly challenging to measure their ages.
In fact, using very distant globular clusters to age-date the first stars in distant galaxies was not possible before the launch of the James Webb Space Telescope. Webb’s increased resolution and sensitivity unveiled the tiny dots surrounding the galaxy for the first time in the First Deep Field image.
The researchers say the Sparkler galaxy is special because it is magnified by a factor of 100 due to an effect called gravitational lensing, where the SMACS 0723 galaxy cluster in the foreground distorts what is behind it, much like a giant magnifying glass. Moreover, gravitational lensing produces three separate images of the Sparkler, allowing astronomers to study the galaxy in greater detail.
“Our study of the Sparkler highlights the tremendous power in combining the unique capabilities of JWST with the natural magnification afforded by gravitational lensing,” says CANUCS team lead Chris Willott from the National Research Council’s Herzberg Astronomy and Astrophysics Research Centre. “The team is excited about more discoveries to come when JWST turns its eye on the CANUCS galaxy clusters [in October].”
Information provided by York University.