Odd supergiant star Betelgeuse is brightening up. Is it about to go supernova?

The star will then "become as bright as the full moon, but it will be concentrated in a single point when it happens."

One of the night sky's brightest stars has been strangely becoming brighter, leading to concerns that it would soon go supernova. Should we truly anticipate such a brilliant heavenly show?

The star in issue is Betelgeuse, a massive star with a reddish hue that can be seen near Orion's unmistakable left shoulder. Betelgeuse, which is 650 light-years away from Earth, is often the tenth-brightest star in the night sky. However, the star has moved up to the seventh position since the beginning of April and is now shining at more than 140% of its "usual" brightness, according to the Twitter account Betelgeuse Status, which monitors the star's activities.

Betelgeuse is a red giant, a massive star that has grown hundreds of times beyond its initial radius after burning up all the hydrogen fuel in its core. According to astronomers, the star is currently fusing helium into carbon and oxygen, a process that lasts tens to hundreds of thousands of years until the star explodes in a supernova. Due to Betelgeuse's latest shenanigans, which started in 2019, some people have begun to believe that the star's dramatic demise may be approaching. It would be the closest supernova explosion in more than 400 years, and if Betelgeuse went bomb, it would be so brilliant that it would be visible throughout the day.

the massive darkening

Betelgeuse is a variable star that frequently alternates between periods of greater and lesser brightness. Betelgeuse has been brightening every 400 days for more over 100 years, then dimming to roughly half of its peak brightness and brightening once again. The star, however, suddenly faded beyond anything that had ever been observed in December 2019, reaching a low that was 2.5 times fainter than its typically dimmest brilliance. Later, it was discovered that the Great Dimming was caused by a massive material ejection from the star's innards, which resulted in a massive dust cloud and blocked our vision of the star.

life's end

Betelgeuse has subsequently returned to its normal brilliance, but since the Great Dimming, the star has not exactly been the same. The star now looks to be undergoing the additional brightening that thrills skywatchers, and its 400-day brightness oscillation period has been cut in half to 200 days. However, the astronomers who talked with Space.com are moderating the supernova predictions.

The primary author of a recent research on Betelgeuse's Great Dimming, Harvard University postdoctoral scholar in theoretical astrophysics Morgan MacLeod, told Space.com that "our best models indicate that Betelgeuse is in the stage when it is burning helium to carbon and oxygen in its core." If those predictions are accurate, it's still tens of thousands or perhaps a hundred thousand years away from exploding.

MacLeod noted that a star's extended life as a red giant continues beyond the helium-burning period, but a star's typical life ends when it runs out of hydrogen and starts to fuse helium in its core. After the helium is gone, the star will continue to burn carbon and oxygen to produce neon and magnesium, which will subsequently be burned to produce silicon. Iron eventually fills the star's core. And at that point, the fireworks start.

"Adding helium nuclei to an iron atom actually extracts energy rather than gives off energy," said MacLeod. "As a result, the star's core abruptly begins to absorb energy rather than undergo a reaction that releases enormous amounts of energy. The star's core collapses on itself somewhat from the inside out as a result of this transformation, creating what is known as a core-collapse supernova.

duration of stellar death

A star can spend billions of years in its hydrogen-burning phase, but after that, each phase gets shorter and shorter.

"The helium-burning phase is several hundred thousand years long," Miguel Montargès, a post-doctoral associate at the Laboratory of Space Studies and Instrumentation in Astrophysics at the Paris Observatory and an authority on Betelgeuse, told Space.com.

The following phase, which lasts for around 10,000 years, is followed by those that last for thousands of years, a century, and finally, a few days or hours immediately before the explosion.

Montargès, like MacLeod, believes that Betelgeuse still has many thousands of years to live and is not very concerned about the recent surprise brightening. He said that while it was only for limited periods of time, the star had in fact before been as brilliant.

According to Montargès, "the current brightening is really quite negligible if we compare it to the Great Dimming." "The magnitude of a star, which is a logarithmic and inversely proportional measure of its brilliance, increased from 0.8 to 1.75 during the Great Dimming. On the other side, we are currently only at approximately 0.1 of the typical peak brightness, which is roughly 0.3.

back to regular

Instead of anticipating a supernova, MacLeod and his colleagues estimate that Betelgeuse will revert to its regular behavior during the next five to ten years, decreasing its cycle of brightening and dimming to the typical 400 days. The article was published on the online repository Arxiv on May 16.

We believe that the event that led to the Great Dimming is connected to the shift in cycle duration, according to MacLeod. We believe that the massive bubble that erupted from the star's interior before to its dimming caused the star's envelope and interior to move in opposition to one another, which is why the star is currently pulsing twice as quickly as it would normally.

The star Betelgeuse is huge. It would reach all the way to Jupiter if we put it in the middle of our solar system. Because of the star's size and location in the Milky Way, astronomers can examine Betelgeuse more thoroughly than they can most other stars.

Other than our sun, "most stars cannot be studied in any detail at all," according to MacLeod. We only notice them as single point sources of light. However, Betelgeuse is large enough for the Hubble Space Telescope and radio telescopes to resolve it.

Those pictures show a fascinating body that is very unlike to our sun. Betelgeuse is not a single smooth sphere of extremely hot plasma; rather, it is a lumpy cluster of bubbling gas, some of which are as big as tiny stars. Betelgeuse's core emits enormous plumes of heated material that ascend to the surface before cooling and returning to the deep. It resembles the sun's cycle when taken very heavily steroidized. Betelgeuse occasionally lets off a bubble so big that it causes a Great Dimming. However, none of it indicates that the star is poised to erupt. Unless the astronomers' presumptions are incorrect, of course.

Would we know if Betelgeuse was poised to go supernova?

Astronomers are able to observe what is occurring in Betelgeuse's outer layers with such clarity thanks to the capabilities of our greatest telescopes that they are able to determine the chemical make-up of the star's atmosphere. But they have no method of discovering what is actually occurring inside the star's core. Is helium actually being burned? Or has it already shifted to fusing carbon? And how would we know if it did so?

According to Montargès, many of the presumptions we have about Betelgeuse are based on studies of other red giant stars. For instance, it is believed that the Milky Way red giant VY CMa, which is 3,900 light-years from Earth in the constellation Canis, is far closer to its death than Betelgeuse. But that star has been steadily declining over the past 100 years, in contrast to the Betelgeuse, which is getting brighter.

VY CMa used to be visible to the unaided eye, according to Montargès. But now that it has ejected so much debris, we can only view it in infrared. We anticipate observing this material expulsion as the star approaches the supernova explosion. Betelgeuse still possesses 95% of its original bulk, whereas VY CMa has already lost around 60% of it.

Betelgeuse was formerly depicted as a yellow star until 2,000 years ago, when poets started depicting it as red, the astronomer continued. That, in Montargès' opinion, may suggest that Betelgeuse is still very young as a red giant.

Third sunHowever, Montargès is aware of the enthusiasm around Betelgeuse's potential demise. The star will eventually burst, making front-page news for months.

According to Montargès, "when it happens, the star will become as bright as the full moon, but it will be concentrated in a single point." If all the lights in a city were turned out for, say, two months and there were no clouds, you could read a book by the light of the supernova. Because of its brightness, it will also be visible throughout the day. During the day, another star will be seen in the sky.

Fortunately, Betelgeuse is too far from Earth for its explosion to be detrimental to humans, even though it is close enough to produce such a show. According to EarthSky, astronomers believe that a huge star explosion would need to occur within 160 light-years of our planet in order for us to see its effects.

The Kepler supernova, also known as SN 1604, was the last supernova known to have occurred in the Milky Way galaxy. It was given the name Johannes Kepler after the scientist who first described it in his book "De Stella Nova."

That supernova, which was 30 times farther away from Earth than Betelgeuse, was reportedly visible throughout the day for more than three weeks, according to historical records.

Montargès anticipates Betelgeuse to soon reenter its boundaries. The star won't be seen for a few months since it will be too near to the sun. To monitor its development, astronomers will have to wait until the end of the summer.

We should start to worry what's going on if it's still as brilliant or brighter in September, Montargès remarked. However, in my opinion, it isn't that fascinating at this point.