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Source: Adam Block, Steward Observatory, University of Arizona
The…strange behavior of one of the brightest stars in the sky – which scientists say exhibits an unusual variation in brightness, going from bright to dim twice as fast as usual – gives science an experiment without previous image of how stars “die”..
Beltegez, a pulsating red supergiant which, due to its size, can be distinguished with the naked eye, is a star located approximately 640 light-years from Earth, in the constellation Orion. This means that light takes 641 years to reach Earth – so if you see the star at night, you are seeing it as it was almost 6.5 centuries ago.
At about 10 million years old, it is much younger than our Sun (5 billion years), but despite its… young age, it has a lot greater mass and therefore shorter lifespan than the Sunwith scientists believing that over the next few millennia it will explode as supernova.
What characterizes the red giant are the brightness variations in 400-day cycles.
However, between late 2019 and early 2020, the star underwent what astrophysicists called “big power outage” as a cloud of dust obscured the red giant.
Now, according to astrophysicist Andrea Dupre of the Harvard Smithsonian Center for Astrophysics, it’s against 150% brighter than its normal brightness and the dimming period of brightness decreased to 200 days – as a result the frequency of the phenomenon has doubled.
This change makes it so the seventh brightest star in the night sky – when he was previously in tenth place.
The life and death of a star
Beltegez is expected to burst at some point the next 10,000 to 100,000 years.
“One of the most exciting things about Beltegez is how we follow ta final stage in the evolution of large stars to take place in near real time for us, something that we had never been able to study in such depth in the past,” notes Dr. Sarah Webb, an astrophysicist at Swinburne University of Technology in Australia.
By observing its behavior, scientists obtain valuable information about the “red giants” before their supernova explosion. When they explode, the intensity is such that the explosion is visible on Earth even during the day.
As science explains, at the end of their lives, stars turn into red dwarfs and begin to they release energymaking them swell, they become unstable and pulsating over periods of hundreds or even thousands of days – what experts and romantics on Earth consider to be the “twinkle” of the stars.
There are records from ancient Egypt of what appears to be a star exploding into a supernova, with descriptions that speak of the appearance of the “second sun”notes Webb.
Beltege’s great loss of luminosity was caused by ejecting a huge mass of gas and dustor what scientists call a “mass massive ejection of an abnormally hot convective cloud”.
The four images from the Hubble Space Telescope show the evolution of the loss of luminosity which scientists believe is due to a cloud of stardust blocking its view from Earth – Credit: NASA, ESA
This mass was several times greater than that of the moon, Webb explains. “If we suddenly lost one of our hands, it would change the way forces move through our bodies. Something similar happened with the unfortunate Beltegez. Throwing away all that mass and now its core and its stability are trying to come backshe notes.
AT study where Dupre and other Harvard and Berkeley scientists collaborated of California, concludes that they will pass five to ten years before Beltegez returns to its normal 400-day cycle.
“After losing luminosity, the light-speed and ray curves of the star are noticeably different from before,” the authors note. “It’s something unheard of. We’ve never seen this before,” adds Webb.
They were the Australian Aborigines who first discovered the Beltege luminosity cycles before Western astronomers, who until 1596 believed that the stars are “immutable and immutable”.
Source: Guardian
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