Seeing Stars

by Deirdre Kelly

The mystery of the universe is that much closer to being solved, thanks to a bedazzling new study co-authored by observational astronomers at York University. Using high-resolution images produced by a Canadian-made instrument on NASA’s powerful James Webb Space Telescope (JWST), researchers at the Faculty of Science have been able to detect distant star clusters, among the oldest objects ever discovered in outer space.

These ancient relics of the universe, previously hidden in the miasma of the Milky Way and linked to a galaxy’s infancy, contain clues about the earliest phases of star formation. Discovering them, says Adam Muzzin, co-author of a recently published paper providing a detailed look at early star formation, will revolutionize the study of astronomy. Previously, those stars remained undetectable, mainly because earlier telescopes – including the mighty Hubble – lacked the technology to pinpoint them in the dark. By comparison, the JWST is six times more powerful than the Hubble, making it a significant game-changer. “It’s expanding our knowledge of the universe, literally before our eyes,” he declares.

A member of the international team that helped to build the Near-Infrared Imager and Slitless Spectrograph (NIRISS), launched last December with the state-of-the-art JWST, Muzzin looked at deep field images of a distant galaxy estimated to be more than nine billion light years away. Surrounding the Sparkler galaxy and making it glimmer are many star clusters, some of which the team age-dated to be extremely old – much older than the main part of the Sparkler galaxy itself. Muzzin and fellow members of the Canadian NIRISS Unbiased Cluster Survey (CANUCS) team – among them York PhD student Ghassan Sarrouh (BSc ’20), another co-author on the study – believe that the Sparkler galaxy, so-called for the compact yellow-red dot-like objects clustering around it, was likely born three billion years after the Big Bang, at the peak of star formation.

It’s a remarkable finding and just the beginning of what Muzzin describes as a new revolutionary period for the study of astronomy. Going forward, he and other CANUCS researchers will continue to receive new JWST-generated images of hundreds of galaxies. The goal is to analyze them in the same way and learn if these very old star clusters exist around all young galaxies in the distant universe, and determine what role they might play in the future growth of the solar system.

Says Muzzin, “These are transformative times in the study of galaxy formation. Already in its first few months JWST is allowing us to see things we only dreamed of a year ago. The next few years of discoveries are certain to be extraordinarily exciting.”  ■

– Image: Thousands of galaxies flood this near-infrared image of galaxy cluster SMACS 0723, known as Webb’s First Deep Field courtesy of NASA, ESA, CSA, STScI

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