James Webb Space Telescope reveals some of the oldest stars in our universe | CBC News

The James Webb Space Telescope (JWST) has promised to take us back to a time when our universe was still in its infancy. And so far it keeps its word.

In a new one Publication in Astrophysical Journala team led by a group of Canadian astronomers has found evidence of some of the oldest known stars.

The stars lie within a globular cluster — a sphere of tens of thousands to millions of stars held tightly together by gravity — in a galaxy only four billion years old, astronomically a mere child considering our universe is roughly 13.8 billion years old is old.

Globular clusters are not well understood, at least in terms of when and how they form. Most galaxies have them; our own Milky Way contains about 150.

But it is not known whether these stars formed before or after the galaxy itself. And above all, astronomers want to know when they formed in connection with the Big Bang.

This intrigued a team of Canadian astronomers as they looked at the first image ever released by JWST.

A bet

When the first images from the newly launched JWST arrived last July, nearly a dozen Canadian astronomers gathered around a table in Halifax. As part of Canada’s NIRISS Unbiased Cluster Survey (CANUCS) team, they were excited to see what new views of the Universe the telescope would reveal. (NIRISS is the Canadian-made Near-Infrared Imager and Slitless Spectrograph Camera on JWST.)

You were not disappointed.

Among the five images, one stood out from the rest: thousands of galaxies piercing the darkness; white, orange and red dots from a time when our universe was still in its infancy.

A particular galaxy was intriguing to some members of the team: an elongated orange streak located near the center of the image. Around it are several yellowish dots, probably densely packed stars with thousands to millions of stars, called globular clusters. Because of these dozen dots surrounding it, the galaxy has been dubbed the “sparkler.”

Some wondered: could this help answer whether or not globular clusters were relics of our ancient universe?

While some believed the answer was yes, others disagreed.

The bet within the group was: old stars vs. young stars. At stake: Exotic candy from a nearby Halifax store.

“There has been a lot of debate as to whether these are young or old to begin with,” said Kartheik G. Iyer, Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics at the University of Toronto and co-lead author of the study.

As all the postdocs gathered and went through various analysis steps, two lead researchers, Roberto (Bob) Abraham, Professor of Astronomy and Chair of the David A. Dunlap Department of Astronomy and Astrophysics at the University of Toronto, and Chris Willott of Herzberg Astronomy and Astrophysics Research Center of the National Research Council Canada, which leads the research, gave them a candy after completing each task.

“Chris and Bob made a bet if that’s young or old? And Bob claimed that’s old,” said Lamiya Mowla, a Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics at the University of Toronto, who is also a co-lead author of the paper.

After weeks of analysis, they concluded that of the 12 objects in the Sparkler, five are not just globular clusters, but some of the oldest known, formed only 500 million years after the Big Bang.

“That really surprised us and also made us very excited, because our Milky Way itself has around 150 of these globular star clusters around it. And we know they’re old, but we don’t know how old they are, when exactly they were born,” Mowla said.

The age of the remaining objects was undetermined. That meant everyone won.

“So yeah, everyone ended up getting some candy, I think,” Mowla said.

A little help from some friends

The galaxy was only visible through something called gravitational lensing, in which a massive object — in this case, a galaxy cluster called SMACS 0723 — bends and magnifies the light of galaxies behind it, bringing them forward and often creating multiple images of the same target.

That’s the beauty of JWST: it can peer into some of the most distant parts of our universe and use the effects of gravitational lensing, which can bring galaxies unreachable to optical telescopes into the foreground. Galaxies that would be too faint are greatly enlarged.

“Because of something like gravitational lensing, these galaxies sometimes get blown up by a factor of 10 to 100, and they get bright enough for our telescope to actually see them, and they get expanded enough for our telescope to resolve,” Iyer said. “And both happen in the sparkler. We believe the sparkler is between 10 and 100 times magnified and we are still working on more accurate models of exactly how much.”

Michel Fich, a professor at the University of Waterloo who specializes in star formation but was not involved in the study, is intrigued by the work and the answers it may provide.

“The big question about [globular clusters] How old are you? Are they the oldest part of our galaxy? Are they the oldest stars in the universe? And the answer is probably yes. But how old is a matter debate these days,” he said.

“[The paper is] “a lot of evidence that globular clusters — a significant number of globular clusters — form very, very early after the Big Bang,” he said.

The paper’s authors said they will now work more to refine their work and collect other data from JWST. But they’re excited about what the new telescope is already revealing.

“Webb’s main job was to find the first stars,” Mowla said. “Because we think so [globular clusters] were born early, these clusters will have those pristine or first stars. If globular clusters are born from this pristine environment when the first stars were born, studying these globular clusters more closely will lead us to the answer to what happened in the Universe.”