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The James Webb Telescope (JWST) has been used by a group of Canadian astronomers, including specialists from the Dunlap Institute for Astronomy & Astrophysics in the Faculty of Arts & Science at the University of Toronto, to identify the most distant globular clusters ever found. These dense groups of millions of stars may be remnants containing the first and oldest stars in the universe.
The Astrophysical Journal Letters on September 29th published an early study of the Webb’s First Deep Field image, which shows some of the very first galaxies in the universe. According to Lamiya Mowla, a post-doctoral researcher at the Dunlap Institute for Astronomy & Astrophysics and co-lead author of the study, “JWST was built to find the first stars and the first galaxies and to help us understand the origins of complexity in the universe, such as the chemical elements and the building blocks of life.”
This finding in Webb’s First Deep Field “confirms the extraordinary power of JWST” by giving an in-depth look at the beginning stages of star formation. The nine billion light-year-distance “Sparkler galaxy” was focused on by the researchers in the finely detailed Webb’s First Deep Field photograph. The compact objects that surround this galaxy and look as tiny yellow-red specks have been given the moniker “sparkles” by scientists. The research team suggested that these sparkles might represent either young clusters of stars that are actively developing, which would have formed three billion years after the Big Bang, at the height of star formation, or older globular clusters. Globular clusters are old collections of stars from the beginning of a galaxy, and they provide information about the early stages of its development and expansion.
The researchers found that five of these compact objects are among the oldest known globular clusters after performing an initial investigation on 12 of these compact objects. “Looking at the first images from JWST and discovering old globular clusters around distant galaxies was an incredible moment,” says Kartheik G. Iyer, a post-doctoral researcher at the Dunlap Institute for Astronomy & Astrophysics and the study’s co-lead author. “One that wasn’t possible with previous Hubble Space Telescope imaging.”
We could model the sparkles and better grasp their physical characteristics, such as how old they are and how many stars they contain, because we could detect the sparkles at a variety of wavelengths. We anticipate that the fact that globular clusters may be seen with JWST at such great distances will encourage additional research and searches for related objects. It is known that the Milky Way galaxy contains roughly 150 globular clusters, but it is unclear exactly how and when these massive collections of stars formed. Although globular clusters can be quite old, astronomers have a very difficult time determining their ages. It has never been done before, and JWST alone makes it possible, to age-date the initial stars in far-off galaxies using globular clusters that are extremely remote.
According to Mowla, “These recently discovered clusters were formed close to the first time it was even possible to form stars.” The ages of the Sparkler galaxy’s globular clusters can be ascertained more easily because it is far more distant than our own Milky Way. Looking at something that happened a long time ago, we are looking at the Sparkler as it was nine billion years ago, when the universe was just four and a half billion years old. It’s simple to distinguish between a five-year-old and a ten-year-old, but difficult to distinguish between a 50-year-old and a 55-year-old based solely on appearance.
The Hubble Space Telescope has not yet been able to detect the Sparkler galaxy’s surrounding compact objects. This changed with JWST’s improved sensitivity and resolution, which allowed Webb’s First Deep Field image to see the faint specks around the galaxy for the first time. The SMACS 0723 galaxy cluster, which is in the foreground, distorts what lies behind it like a large magnifying glass, causing gravitational lensing, which magnifies the Sparkler galaxy by a factor of 100. In addition, the Sparkler is visible in three different views thanks to gravitational lensing, which enables astronomers to examine the galaxy in more detail.
According to Chris Willott, CANUCS team leader from the Herzberg Astronomy and Astrophysics Research Centre of the National Research Council, “Our study of the Sparkler highlights the tremendous power in combining the unique capabilities of JWST with the natural magnification afforded by gravitational lensing.” The team is anticipating more discoveries when JWST focuses on the CANUCS galaxy clusters starting next month.
The new data from JWST’s Near-Infrared Camera (NIRCam) was integrated with historical Hubble Scape Telescope images by the researchers. In order to look beyond what is visible to the human eye and even the Hubble Space Telescope, NIRCam uses longer and redder wavelengths to detect dim objects. Observing small objects was made possible by the great resolution of JWST as well as magnifications brought on by the galaxy cluster’s lensing.
Due to the absence of oxygen emission lines, which are observable spectra emitted by young clusters that are actively producing stars, the Near-Infrared Imager and Slitless Spectrograph (NIRISS) instrument on the JWST gave independent confirmation that the objects are elderly globular clusters. The geometry of the triple-lens images of the Sparkler was also deciphered with the aid of NIRISS.
According to Marcin Sawicki, a professor at Saint Mary’s University and co-author of the study, “JWST’s made-in-Canada NIRISS instrument was crucial in helping us understand how the three images of the Sparkler and its globular clusters are connected.” Sawicki also holds a Canada Research Chair in Astronomy. It became evident that several of the Sparkler’s globular clusters are orbiting the Sparkler galaxy rather than simply being in front of it by accident after seeing them imaged three times.
Beginning in October 2022, JWST will observe the CANUCS fields. Using its data, it will examine five enormous clusters of galaxies, around which the astronomers anticipate discovering additional similar systems. Future research will model the galaxy cluster to comprehend the lensing effect and do more thorough investigations to interpret the histories of star formation. York University as well as institutions in the US and Europe are participating institutions. The Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada provided funding for the study.