'Once in every 80 years’: Rare nova explosion of T Coronae Borealis set to erupt soon, making it brightest star in night sky

For T CrB, that event appears to reoccur, on average, every 80 years. (Image: AI Generated)

Astronomers are eagerly awaiting a rare cosmic event. A distant star, T Coronae Borealis, is expected to erupt soon. This explosion will make it briefly visible in the night sky. For a few days, it will shine as brightly as the North Star. The star last erupted in 1946, and scientists believe another outburst is near.

What Makes T Coronae Borealis Special?
T Coronae Borealis, also called the Blaze Star, is usually too faint to see. However, about every 80 years, it undergoes a thermonuclear explosion. This transforms it into one of the 50 brightest stars in the sky. The star is located in the Corona Borealis constellation, which resembles a crown.

Léa Planquart, an astrophysicist at the Université libre de Bruxelles, explains its unique structure to timeanddate.com. "T Coronae Borealis consists of two stars," she says. "A cool red giant and a dense white dwarf." The white dwarf slowly pulls hydrogen from its larger companion. This process, sometimes called "stellar vampirism," creates a ring of material around it.

Scan between Vega and Arcturus, where the distinct pattern of Corona Borealis may be identified. (Image: NASA)

Over time, the white dwarf accumulates too much matter. When pressure builds up, it triggers a thermonuclear explosion. This event, known as a nova, expels the gathered material. Unlike a supernova, which destroys a star, a nova allows the cycle to continue.

When Will the Blaze Star Erupt?
Recent observations suggest the explosion could happen soon. From 2015 to 2023, the system showed increased brightness. This is similar to the pattern seen before its last eruption in 1946.

“The system entered a superactive phase,” says Planquart. “The accretion disc around the white dwarf expanded and became hotter.” This increased brightness allowed more material to transfer to the white dwarf. Scientists believe this build-up may trigger an explosion.

However, the system has now returned to a quieter state. This makes predicting the exact timing difficult. "The explosion could happen in the coming months or next year," Planquart notes.

A Rare Opportunity for Astronomers
T Coronae Borealis offers a unique chance for scientific study. The event will be closely monitored by telescopes worldwide.

“This is an exceptional opportunity to study nova explosions,” Planquart says. “When it erupts, it will be one of the most observed objects.”

The findings about T Coronae Borealis were published in Nature. Until the eruption happens, astronomers and skywatchers remain on high alert.