Astronomers from Liverpool John Moores University and the University of Montpellier have developed an “early warning” system to warn when a giant star is nearing the end of its life. supernova explosion. The work was published today (October 13, 2022). Monthly Notices of the Royal Astronomical Society.
In this new study, the investigators found that massive stars (typically between 8 and 20 solar masses) in the final phase of their lives, the “red supergiant” phase, suddenly dim by about a hundred times in visible light. they weaken in the last few months before dying. This dimming is caused by a sudden accretion of material around the star, which obscures its light.
Red supergiants are spectral type K or M stars with a supergiant luminosity class (Yerkes class I). By volume, they are the largest stars in the universe. However, they are not the most massive or flashy. Betelgeuse and Antares are the brightest and most famous red supergiants.
Until now, it was not known how long it took the star to collect this material. For the first time, scientists have simulated what red supergiants might look like when placed inside these pre-explosion ‘cocoons’.
Old telescope archives show that there are images of stars that continue to explode a year after the image was taken. The stars are normal in these images, meaning they cannot yet form a theoretical star cocoon. This suggests that the cocoon is harvested in less than a year, which is considered extremely fast.
Benjamin Davies, from Liverpool John Moores University and lead author of the paper, said: “The dense material almost completely obscures the star and makes it 100 times fainter in the visible part of the spectrum. This means that the day before the star explodes, you won’t even be able to see it’s there.” He adds: “Until now, we have been able to obtain detailed observations of supernovae within hours of their occurrence. With this early warning system, we can observe them in real time, point the world’s best telescopes at their progenitor stars, and see them literally before our eyes.” we can follow the breakdown in meaning.
Citation: “The explosion is coming: a view of red supergiants at the point of core collapse” by Ben Davies, Bertrand Plez and Mike Petrault, 13 October 2022, Monthly Notices of the Royal Astronomical Society.
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