Massive stars give a warning sound that they are about to go supernova

Astronomers from Liverpool John Moores University and the University of Montpellier have developed an “early warning” system to signal that a massive star is about to end its life in a supernova explosion. The work was published in Monthly Notices of the Royal Astronomical Society.

In this new study, researchers determined that massive stars (usually from 8 to 20 solar masses) in the last phase of their life, called ‘red supergiantphase, will suddenly become about a hundred times weaker visible light in the last few months before his death. This dimming is caused by a sudden accretion of material around the star that blocks out its light.

Until now, it was not known how long it took the star to accumulate this material. Now, for the first time, researchers have modeled what red supergiants might look like when they are in these pre-explosion “cocoons.”

Old telescope archives show that there are indeed images of stars that exploded about a year after the picture was taken. In these images, the stars appear to be normal, meaning they have not yet formed a theoretical circumstellar cocoon. This indicates that the cocoon is assembled in less than a year, which is considered extremely fast.

Benjamin Davies of Liverpool John Moores University and lead author of the paper says: “The dense material almost completely obscures the star, making it 100 times fainter in the visible part of the spectrum. This means that a day before the star exploded, you likely couldn’t would see that it was there.” He adds: “Until now, we could only get detailed observations of supernovae a few hours after they have already occurred. With this early warning system, we can prepare to observe them real timeto point the world’s best telescopes at progenitor stars and watch them literally tear apart before our eyes.”