How a telescope in Saskatoon helped discover a supernova that happened 35 million years ago

Every night for a year a high-powered robotic telescope in Saskatoon captures images of 600 nearby galaxies over an eight-hour stretch, scanning for exploding stars known as supernovas.

In the early hours of March 20, Saskatoon’s PROMPT-USASK Skynet robotic telescope found its first one.

"It was fun to finally get a discovery," said Daryl Janzen, instructional assistant in physics and engineering at the University of Saskatchewan.

Colleagues in Chile and Australia confirmed the discovery, and Janzen added the supernova occurred in a galaxy 35 million light years away.

“The supernova actually occurred 35 million years ago, in the past, but we’re only just seeing it now because it’s taken 35 million years for the light from this explosion to finally reach our telescope,” Janzen said.

Through the robotic telescope the exploding looks like a tiny point of light in the distance. Janzen said this was a type two supernova, meaning it marked the end of the life of a massive star by imploding.

Janzen said he predicts the star captured on the telescope was at least eight times the size of our sun, but it could be up to 100 times more massive.

The supernova was named SN 2021gmj. It’s the first supernova discovered by the university’s robotic telescope which was installed in April 2020 at Sleaford Observatory north of Colonsay.

The telescope is part of the international astronomy network called Skynet, Janzen said.

Janzen said supernovae help astrophysicists better understand stellar evolution and the evolution of galaxies.

“Also, because supernovae are so bright that we can see them at very far distances, there are important applications to distance measurements that contribute to our understanding of the evolution of the universe as a whole,” he said.