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This star who does not want to die

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Artistic representation of a supernova like iPTF14hlsA star that reaches the end of life continues to shine, say astronomers, who are now wondering whether our understanding of the stages of stellar evolution should be questioned.

Supernovas have been observed by thousands for hundreds of years, and in all cases observed; this type of explosion marks the last stage in the life of the stars.

However, scientists associated with the Las Cumbres Observatory (LCO) in the United States may have found an exception to the rule. Researcher Peter Nugent and his colleagues have spotted a star that seems to refuse to stop shining. It has already exploded several times in recent decades without ever shining in the sky.

This supernova looks nothing like what we have seen so far, especially in the last 20 years, when 5,000 supernovas were discovered.

Peter Nugent

“Although the light spectra resemble those of normal supernova explosions during the collapse of the hydrogen-rich nucleus, they fade and fade at least five times more slowly, extending an event that normally lasts 100 days to more than two years. Adds the researcher.

This supernova, nicely named iPTF14hls, was first discovered in September 2014. At the time, it was not abnormal and was considered an ordinary supernova.

However, after a few months, astronomers noticed that its luminosity had begun to increase after having disappeared.

This peculiarity pushed the authors of these works published in Nature magazine to push their research. They then noted with astonishment that an explosion had occurred at the same place in 1954.

The star survived the explosion to explode again in 2014.

This supernova demolishes everything we thought we knew about their operation. This is the biggest puzzle I’ve encountered in my study of stellar explosions.

Iair Arcavi, University of California at Santa Barbara

According to the information gathered, this star would be at least 50 times more massive than the Sun. It could be the largest stellar explosion ever detected. Moreover, the magnitude of this explosion may explain why it cannot be associated with any of the traditional theories of star death.

Thus, iPTF14hls could be the first example of a new category of supernova (Pulsational Pair Instability Supernova).

According to this theory, it is possible that the phenomenon is born when a very massive and very hot star generates antimatter in its nucleus.

Daniel Kasen, Lawrence Berkeley Laboratory

“It would cause a violent instability of the star and repeated light eruptions for years,” says Daniel Kasen.

A process that could be repeated for several decades before the final explosion and the collapse of the star, which will become a black hole.

Until now, scientists thought that such explosions had occurred in the early universe, but that they could not be observed nowadays.

It’s like we find a dinosaur today. If so, the question would be whether it’s really a dinosaur!

Andy Howell, OLC

Indeed, the new theory (Instability Pulsational Pair Instability) can not completely explain all the data obtained for this astronomical event. For example, the energy released by the supernova is greater than the theoretical predictions.

This supernova could therefore belong to a completely new phenomenon for science.

Astronomers continue to follow its evolution and hope to succeed in explaining it in the coming years.

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