Astronomers track the death of a red supergiant for the first time

(ORDO NEWS) — Unique observations have shown that stars can undergo profound internal changes, emitting bursts of radiation and matter before finally exploding into supernovae.

Red supergiant’s are the largest of the stars. Their existence ends in a Type II supernova explosion , leaving behind only a black hole or neutron star. One of these flares was seen in the sky on September 16, 2020.

But, unlike the previous ones, the supernova predecessor SN 2020tlf was followed. By that time, the telescopes at the Keck Observatory in Hawaii had been observing the red supergiant for 130 days, like a “ticking bomb” ready to explode at any moment.

The star itself was located 120 million light-years away, in the galaxy NGC 5731, and had a mass of about 10-12 solar masses. Previously, it was believed that the transition to a supernova occurs relatively calmly, and past data did not reveal any abrupt changes that would precede the explosion.

However, new observations have shown that at least some of the red supergiant’s undergo profound structural changes before erupting into supernovae. Scientists write about this in an article published in The Astrophysical Journal .

The find was made as part of the Young Supernova Experiment survey, using the Pan-STARRS and WM Keck telescopes.

Even months before the SN 2020tlf supernova, they recorded extreme events that accompanied the star’s transition to an explosion: powerful bursts of radiation and ejections of matter into the surrounding gas and dust cloud.

“We have never noticed such intense activity in a dying red supergiant,” said Raffaella Margutti, one of the authors of the new work, “and now we saw bright ejections, collapse and flare.”

The sharp changes that this star underwent on the eve of its death testify to serious internal changes that preceded the final explosion.

“The discovery of new events like SN 2020tlf will significantly affect our understanding of the last months of stellar evolution,” the authors added, “and will unite theorists and observers in search of an answer to the question of what exactly is happening to red supergiant’s on the eve of their death.”

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