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Jan. 15, 2020
The brightness of one of the brightest stars in the Milky Way has dropped drastically since mid-November.
The Betelgeuse star weakens. (Photo: AFP / P. Kervella)
The giant star Betelgeuse has seen its luminosity fall for a few weeks. The event puts astronomers in effervescence, because it could announce its explosion in supernova, an extremely rare phenomenon in our galaxy.
Located in the constellation Orion, this "red super giant", almost a thousand times larger than the Sun, shines brightly in the winter sky, where it is visible to the naked eye thanks to its orange color.
The star was among the ten brightest in the galaxy, but since mid-November, "its luminosity has dropped drastically, in the order of 70%", explains to AFP Pierre Kervalla, from Paris Observatory - PSL.
Image above: Wide-field view of the region o Betelgeuse Orion Alpha Orionis star (yellow pale star) . Image Credits: IAU and Sky & Telescope.
Alerted by amateur observers, astronomers launched a vast observation campaign in December, mobilizing the largest telescopes on the planet, including the Very Large Telescope in Chile.
"It's boiling!" We have set up a research group around the world to use all the instruments capable of imaging the surface of Betelgeuse, ”says Eric Lagadec, from the Lagrange laboratory of the Côte d'Azur observatory.
Hundreds of amateur astronomers are involved, and "spend their nights in their gardens or their favorite observation sites" in order to provide additional measures, says this CNRS researcher.
Several hypotheses
Several hypotheses have been put forward: it could be an ejection of gas forming dust and hiding the radiation, or else the death of Betelgeuse.
The latter scenario would result in a supernova explosion. If it seems unlikely in the near future, it makes astronomers dream: the star at the end of its life having no more "fuel" (from nuclear fusion), its heart would collapse on itself and would form a neutron star, a very compact object that creates a shock wave completely dislocating the star, all in just a few hours.
From Earth, we would then observe with the naked eye a point as bright as the Moon in the day and night sky. To this would be added a nice spectacle, "that of an echo of light propagating around, like circles in the water", specifies Pierre Kervalla.
After several weeks, this point would disappear and form a nebula, visible in the sky for thousands of years, like that of the Crab, residue of the supernova which occurred in 1054 which was reported by Chinese astronomers.
"An unforgettable spectacle"
“It would be an unforgettable spectacle for all of humanity. I hope to be able to see a supernova in my lifetime, ”says Eric Lagadec. Because this phenomenon only happens once a century in the Milky Way, and the last formation of supernova observed dates back to 1604.
The Betelgeuse explosion is expected since the star, "only" 10 million years old, is indeed at the end of its life. But it's hard to predict exactly when she will die, as there are no warning signs.
“It's a bit like an earthquake; the day before the explosion, the star will be the same, ”underlines Pierre Kervalla. It could therefore happen in the coming weeks as in 100,000 years.
Giant star (supernova) explosion
Either way, it would be safe for our planet, which Betelgeuse is 600 light years away. "If we see it explode from here, it will mean that the explosion took place physically 600 years ago," recalls Pierre Kervalla.
Scientifically, the event would allow astronomers to follow directly, and for the first time in history, the different phases of the explosion, a precious gauge to measure the expansion of the Universe. We would also understand what will happen to the future generation of stars.
Related articles:
A giant red star is acting weird and scientists think it may be about to explode
https://orbiterchspacenews.blogspot.com/2019/12/a-giant-red-star-is-acting-weird-and.html
Betelgeuse Braces for a collision
https://orbiterchspacenews.blogspot.com/2013/01/betelgeuse-braces-for-collision.html
The Flames of Betelgeuse
https://orbiterchspacenews.blogspot.com/2011/06/flames-of-betelgeuse.html
Related link:
Paris Observatory - PSL: https://www.obspm.fr/-observatoire-de-paris-.html?lang=en
Images (mentioned), Animation, Text, Credits: ATS/Paris Observatory (PSL)/NASA/Wikipedia/Orbiter.ch Aerospace/Roland Berga.
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