An artist's rendition of a supernova.

(NASA, ESA, G. Bacon (STSci))

At a Glance

Astronomers have discovered a decades-old supernova that is the first of its kind.The exploding star is 50 times the mass of the sun and is the longest-lived in history.It was observed in September 2014, but researchers discovered it has been exploding since 1954.

A star that appeared to have exploded and died multiple times refuses to stop existing completely, and researchers believe this everlasting supernova isthe first of its kind.

Typically, supernovae mark the end of a star’s lifespan and shine brightly for 100 days before finally fading out. However, a celestial blast named , according to a study on the discovery.

When in California, they thought it was nothing out of the ordinary, according to a release on the study. But after several months of observation, they knew they were seeing something rare.

“This supernova breaks everything we thought we knew about how they work,” study lead author Iair Arcavi said in the release. “It’s the biggest puzzle I’ve encountered in almost a decade of studying stellar explosions.”

According to the researchers, the star is 50 times the mass of the sun and its explosion is the longest-lived in history. Arcavi says it maylikely even be the most massive supernova ever seen.

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"My first thought was that this must be some nearby star in our galaxy, ," he told CNN. "But when we got the first spectrum of it, we saw that it was, in fact, a supernova 500 million light-years away. My mind was blown. The fact that it got bright and dim five times was very unusual. We'd never seen a supernova do that before."

After looking at archived data, the scientists realized this same star was observed in 1954, exploding and continuing to survive, according to the release.

Arcavi and his team believe the supernova is the first example of the “Pulsation Pair Instability Supernova” theory, according to the study. This theory suggests the cores of a massive star become so hot that it begins to convert energy into matter and antimatter.

“When that happens, the star becomes unstable and can partially explode, blowing off its outer parts, but leaving the core intact," Arcavi told CNN. "The star then stabilizes and can go through this process multiple times every few years or decades. Eventually, it will explode completely. We've never seen such a supernova before, so ours would be the first candidate."

Despite the likelihood, Supernova iPTF14hls still cannot be fully explained by this theory.

"These explosions were only expected to be seen in the early universe and should be extinct today," Las Cumbres Observatory supernova group leader and study co-authorAndy Howell said in the release. "This is like finding a dinosaur still alive today. If you found one, you would question whether it truly was a dinosaur."

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The energy being released from the supernova is greater than what would be predicted by the theory, according to the scientists. The theory also predicts that all of the star’s hydrogen would have been lost in the 1954 explosion, but a lot of the chemical element remained after the explosion in 2014.

"If this is the first pulsational pair-instability supernova, we need to figure out why it doesn't look exactly as predicted," said Arcavi. "Otherwise, it's something completely new. There are no existing theories that can fully explain this supernova, pulsational pair-instability is our best guess, but it might be something completely new."

The scientists hope that as the supernova continues to expand, it will become more transparent, which will allow them to get a closer look, according to CNN.

"We might be able to see how much total mass exploded, and maybe catch a glimpse of any internal power source that has been providing the extra energy to power this supernova for so long," Arcavi said. "The Hubble Space Telescope is also planned to look at this supernova in about a month. Hubble's increased resolution could show us what the neighboring stars of this supernova look like, and that might shed some light on what kind of star exploded here.

"I'd like to know how common these explosions are," he added. "Was this a super rare beast, or will we find more now that we know what to look for?"