Stars can ‘hiccup’ – and they could reveal secrets about how the universe is shaped

It’s previously been predicted that stars can ‘hiccup’ – yes, really – but now a new study has found evidence of this rare event occurring in a star in the final stages of its life before exploding.

Seen in massive stars ranging from 60 to 150 times the mass of our sun, Northern Irish scientists say confirmation that this phenomenon occurs is a “major step” towards understanding how these huge stars operate and shape our universe.

The more scientific term for the hiccupping is ‘pulsational pair instability’ or PPI for short, and it concerns massive stars developing hot cores “which contract and expand in rapid succession” in the last few moments of their lives.

A key signifier or “signature” of this event occurring are shells of material, ejected whenever the stars pulsate, which produce light when they collide with each other.

Except this light – or the event itself – has never been observed by astronomers due to faint nature of the collisions as opposed to the final supernova.

They can be more noticeable when the timing between the aforementioned pulsations is “just right”, and this occurred with a star in December 2020.

Dr Charlotte Angus, lead author and a researcher at the Astrophysical Research Centre at Queen’s University, Belfast, said: “We identified a new bright supernova, now named ‘SN2020acct’, in a nearby spiral galaxy called NGC 2981. The light from SNS2020acct disappeared pretty quickly.

“But then in February 2021, we saw light coming from the same region of the galaxy again.

“This is very unusual as supernovae normally don’t reappear.

“When it appeared for a second time, however, it looked very different – now it was expanding much faster, suggesting the core of the star had exploded, marking the end of its life.

“This was the actual supernova explosion, suggesting that the first flare may have been the elusive PPI.”

And it was exactly that, with the scientists observing a “PPI candidate” for the first time when shell collisions were taking place.

The open access article was published in The Astrophysical Journal on Tuesday.

It's not the only unusual thing to be discovered about our universe, as scientists have suggested there was actually a 'second big bang', and claimed that part of our sun is broken - and they don't know why.

Pretty cool, huh?

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