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

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

In a new paper published in the Astrophysical Journal, a team lead 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 tightly held together by gravity — in a galaxy that is just four billion years old, a mere child in astronomical terms, considering our universe is roughly 13.8 billion years old. 

Globular clusters aren't 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's unknown whether or not these stars formed before the galaxy itself did or after. And most importantly, astronomers want to know when they formed in relation to the Big Bang. 

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

Last July, as the first images from the newly launched JWST were coming in, almost a dozen Canadian astronomers gathered around a table in Halifax. Part of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS) team, they were anxious to see what new views of the universe the telescope might reveal. (NIRISS is the Canadian-made Near-Infrared Imager and Slitless Spectrograph camera on JWST.)

They were not disappointed.

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

To some members of the team, there was one particular galaxy that was intriguing: an elongated orange streak located nearly in the centre of the image. Around it, several yellowish dots, likely densely packed stars containing thousands to millions of stars, called globular clusters. Due to these dozen dots surrounding it, the galaxy began to be referred to as the "Sparkler."

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

While some believed the answer to be yes, others disagreed.

Wagers were made among the group: Old stars vs. young stars. At stake: Exotic candy from a nearby store in Halifax.

"There was a lot of debate going on about whether these are young or old immediately, right off the bat," 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.