Astrophysics logo.
Dec. 27, 2020
The star Betelgeuse. Image Credits: Gentside/Étoiles
Lately, one of winter's most remarkable constellations, Orion "the Hunter", looks a little different in the sky. In question, the star sitting on his right shoulder and called "Alpha Orionis, alias Betelgeuse, is much less luminous than it has been during the twenty-first century.
Is she at the end of her life, and about to implode into a supernova? An article by researchers at the University of Villanova (United States), published in The Astronomer's Telegram in December 2019, suggested this. Since then, speculations have multiplied.
Credit: AAVSO
The light curve estimates, provided by the American Association of Variable Star Observers (AAVSO), confirmed the claim that the star has faded by about one magnitude (+0.2) since the month of October.
This is just over half of its usual magnitude, between + 0.5 to + 1.5. Changes visible to the naked eye, but not exactly unusual for a variable star like Betelgeuse - it beats cyclically under the impetus of a variety of processes occurring around it. Yet they continue to intrigue the astronomical community.
The hope of a supernova
Betelgeuse is a red giant star 12 times more massive than our Sun and about 700 light years away. It is partly famous for its brightness, making it on the list of the ten brightest stars in the sky. According to scientists, she would have now lost her spot, becoming so dark that she would no longer even reach the top 20.
Its variations in intensity have been observed since 1836, with the discoveries of astronomer Sir John Herschel. The star has been particularly watched since, and for good reason: it is one of the closest candidates to our galaxy for a nearby supernova.
Animation above: Animation of a gigantic star exploding in a “core collapse” supernova. Supernovae are one way that galaxies eject metal-enriched gases into the circumgalactic medium. Animation Credits: NASA/JPL-Caltech.
These impressive phenomena are frequently recorded in distant galaxies, but such an event has never been observed in the Milky Way in the telescopic era. The last would date from 1604, with the supernova of the star of Kepler, of the constellation Ophiuchus.
In addition, a red giant like Betelgeuse lives fast and dies young, depleting its hydrogen supply in just under 10 million years. It “carbides”, in a way. The star is therefore destined to undergo an implosion. But it could just as well happen in 100,000 years as tonight.
Change in our view of the sky
So, this loss of radiance, the prelude to a spectacular phenomenon or false alarm? Astronomers are not sure. A supernova only 700 light years away would certainly be the opportunity to study one up close.
Not only would every optical telescope be pointed at the explosion. But the Laser Interferometer Gravitational-Wave Observatory (LIGO) could also study gravitational waves. Especially since we are safe from the lethal radiation of Betelgeuse, outside the “destruction zone” 50 light years away.
If so ... don't worry. We are not in danger. It's about 650 light-years away (which means if it explodes in 5 minutes, it actually exploded in the 14th century).
Betelgeuse animation from burst photos shows green rays on the surface
Although at the moment no one really knows what will happen to the famous star, its luminosity drop is more severe than normal, giving rise to hope that this exceptional astronomical event will occur.
If so, it would then be visible in detail from Earth. Even with the naked eye, we could see Betelgeuse's luminosity increasing for a few hours or even days, then gradually decreasing for a few months until it disappeared.
Related articles:
Hubble Helps Uncover the Mystery of the Dimming of Betelgeuse
https://orbiterchspacenews.blogspot.com/2020/08/hubble-helps-uncover-mystery-of-dimming.html
The Betelgeuse star turns pale: "It's boiling!"
https://orbiterchspacenews.blogspot.com/2020/01/the-betelgeuse-star-turns-pale-its.html
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
Images (mentioned), Animation (mentioned), Video (NASA), Text, Credits: AFP/Orbiter.ch Aerospace/Roland Berga.
Greetings, Orbiter.ch
