The James Webb Space Telescope (JWST) is a space telescope that is being built by NASA in partnership with the European Space Agency (ESA) and the Canadian Space Agency (CSA). It is expected to be launched in October 2021, and it will be used to study a wide range of celestial objects, including planets, stars, galaxies, and other phenomena in the universe. It is expected to provide detailed images and spectra of objects in the universe, and to help astronomers better understand the origins and evolution of the universe.
Using the James Webb Space Telescope, researchers from the CAnadian NIRISS Unbiased Cluster Survey (CANUCS) team have 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.
The early analysis of Webb’s First Deep Field image, which depicts some of the universe’s earliest galaxies, is published today in The Astrophysical Journal Letters.
“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,” says Lamiya Mowla, Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics at the University of Toronto and co-lead author of the study. “This discovery in Webb’s First Deep Field is already providing a detailed look at the earliest phase of star formation, confirming the incredible power of JWST.”
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 with active star formation that were created 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.
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 discovery in Webb’s First Deep Field is already providing a detailed look at the earliest phase of star formation, confirming the incredible power of JWST.
Lamiya Mowla
“Looking at the first images from JWST and discovering old globular clusters around distant galaxies was an incredible moment, one that wasn’t possible with previous Hubble Space Telescope imaging,” says Kartheik G. Iyer, Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics at the University of Toronto and co-lead author of the study. “Since we could observe the sparkles across a range of wavelengths, we could model them and better understand their physical properties, like how old they are and how many stars they contain. We hope the knowledge that globular clusters can be observed at from such great distances with JWST will spur further science and searches for similar objects.”
There are over 150 globular clusters in the Milky Way galaxy, and 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.
“These newly identified clusters were formed close to the first time it was even possible to form stars,” says Mowla. “Because the Sparkler galaxy is much farther away than our own Milky Way, it is easier to determine the ages of its globular clusters. We are observing the Sparkler 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 as guessing a person’s age based on their appearance it’s easy to tell the difference between a 5- and 10-year-old, but hard to tell the difference between a 50- and 55-year-old.”
Until now, astronomers could not see the surrounding compact objects of the Sparkler galaxy with the Hubble Space Telescope (HST). 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.
“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 next month.”
The scientists combined old HST data with fresh information from the Near-Infrared Camera (NIRCam) on JWST. In order to see beyond what the human eye and even HST can see, NIRCam detects faint objects by employing longer and redder wavelengths. Observing small objects was made possible by the great resolution of JWST as well as magnifications brought on by the galaxy cluster’s lensing.
Since new clusters that are actively producing stars do not emit oxygen emission lines with observable spectra, 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.
“JWST’s made-in-Canada NIRISS instrument was vital in helping us understand how the three images of the Sparkler and its globular clusters are connected,” says Marcin Sawicki, Canada Research Chair in Astronomy, professor at Saint Mary’s University and study co-author. “Seeing several of the Sparkler’s globular clusters imaged three times made it clear that they are orbiting around the Sparkler galaxy rather than being simply in front of it by chance.”
Beginning in October 2022, JWST will study the CANUCS fields. Using JWST data, the researchers will examine five enormous clusters of galaxies, around which they 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.
Collaborating institutions include York University and institutions in the United States and Europe. The Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada supported the research.
