The James Webb reveals the oldest star clusters in the Universe

Do you remember the photograph that accompanies this article? This is the first image of deep space obtained by the James Webb Space Telescope and one of the first five that were made public last July. But now, a team of Canadian researchers from the CANUCS survey (Canadian NIRISS Unbiased Cluster Survey) has just identified the most distant globular clusters discovered to date. These are dense ‘stellar packages’ made up of millions of stars at a very short distance from each other and which, as explained in an article recently published in ‘The Astrophysical Journal Letters’, could be the ‘relics’ that contain the first and oldest stars in the Universe. “The James Webb – explains Lamiya Mowla , of the Dunlap Institute for Astronomy and Astrophysics of the University of Toronto and co-lead author of the study – was built to find the first stars and the first galaxies and to help us understand the origins of complexity in the universe. Universe, such as chemical elements and the building blocks of life. This discovery, made in the First Webb Deep Field, already provides a detailed look at the earliest phase of star formation, confirming the incredible power of the telescope.” Examining that first deep-field image from Webb in detail, the researchers focused on what they called ‘the Sparkler galaxy,’ nine billion light-years away. This galaxy gets its name from the compact objects that appear as small yellow and red dots around it, which scientists refer to as ‘flashes’. Related News standard No Webb and Hubble telescopes simultaneously capture NASA’s impact on an asteroid Judith de Jorge standard No DART Mission All eyes on DART mission Patricia Biosca The team postulated that these bright spots could be young clusters that They actively form stars, born three billion years after the Big Bang at the peak of star formation in the Universe. Globular clusters are ancient collections of stars from a galaxy’s infancy and contain clues about its early stages of formation and growth. Sure enough, from their initial analysis of 12 of these compact objects, the researchers determined that five of them are not just globular clusters, but are among the oldest known. “Looking at the first JWST images and discovering old globular clusters around distant galaxies was an incredible moment, something not possible with previous images from the Hubble Space Telescope,” said Kartheik G. Iyer, also a co-lead author of the study. Since we observed the flares over a wide range of wavelengths, we were able to model them and better understand their physical properties, such as how old they are and how many stars they contain. We hope that knowing that globular clusters can be observed from such great distances with James Webb will further stimulate science and the search for similar objects.” Before the Webb, impossible Around our own galaxy, the Milky Way, around 150 globular clusters are known, and exactly how and when these dense ‘packs’ of stars were formed is not well understood. Astronomers know that globular clusters can be extremely old, but measuring their ages is incredibly difficult. Using very distant globular clusters to date the age of the first stars in distant galaxies is something that has not been done before and is now only possible thanks to the James Webb Space Telescope. “These newly identified clusters formed very close to the time when stars were first likely to form,” explains Mowla. Because the Sparkler galaxy is much further away than our own Milky Way, it is easier to determine the ages of its globular clusters. We are looking at that galaxy as it was nine billion years ago, when the Universe was only four and a half billion years old, looking at something that happened a long time ago. Think of it like guessing a person’s age based on their appearance: it’s easy to tell the difference between a 5-year-old and a 10-year-old, but hard to tell the difference between a 50-year-old and a 55-year-old.” Until now, astronomers with the Hubble Space Telescope have been unable to see the compact objects that exist around the Sparkler galaxy. But this has changed thanks to the increased resolution and sensitivity of the Webb, which for the first time clearly shows the small dots around the galaxy. The Sparkler galaxy is special because it is magnified by a factor of 100 due to gravitational lensing, in which the foreground galaxy cluster SMACS 0723, much closer to us, distorts what lies behind, acting as a giant magnifying glass. Additionally, gravitational lensing produces three separate Sparkler images, allowing astronomers to study the galaxy in even greater detail. “Our Sparkler study highlights the tremendous power of combining the unique capabilities of JWST with the natural magnification offered by gravitational lensing,” says CANUCS Team Leader Chris Willott. The team is excited about this one and the discoveries yet to come, when JWST sets its sights on the CANUCS galaxy clusters next month.” In their study, the researchers combined new data from James Webb’s Near Infrared Camera (NIRCam) with archival data from Hubble. NIRCam can detect very faint objects using longer, redder wavelengths to see beyond what is visible to the human eye and to Hubble. It was the combination of the magnification due to gravitational lensing and the high resolution of the new telescope that made observation of these compact objects possible. The Canadian-made James Webb’s NIRISS (Near-Infrared Imager and Slitless Spectrograph) instrument provided independent confirmation that the objects are indeed old globular clusters, since the researchers did not observe the oxygen emission lines that are common in young clusters that are forming stars. NIRISS also helped unravel the geometry of Sparkler’s triple-lens images. “The NIRISS instrument,” says Marcin Sawicki, Canada Research Professor of Astronomy and co-author of the study, “was vital in helping us understand how the three Sparkler images and their globular clusters are connected. Looking at three images of several of the globular clusters, it became clear that they are orbiting the galaxy rather than just in front of it by chance.” MORE INFORMATION news No Our radio telescopes are detecting mysterious signals from distant galaxies: what is the origin of FRBs? news No ‘ghost’ island emerges in the Pacific last seen in 2006 Starting in October, James Webb will also observe the deep space fields of CANUCS, focusing on five massive galaxy clusters around which researchers hope find more such systems.