A new, unpublished study is making waves on the internet claiming that one of the brightest stars in the night sky could die in a spectacular explosion in our lifetime.
The study, now available on serverarXiv preprint online, surmises that Red giant star Her betel treeleft shoulder of the constellation onion also known as Alpha Orionis, may have less than three hundred years of fuel left in its core. When star burns through those last drops, its core will collapse into a black hole and in the process, the outer layers of the star will explode at colossal speeds of up to 25,000 miles (40,000 km) per second. This fiery collapse is what astronomers call supernova explosion, and in the case of Betelgeuse, it would be a spectacular sight to observers on Earth. Because the star is only 650 light year from Earth, those layers of gas and dust will be as bright as a full moon in our sky in a few weeks.
The problem is that most astronomers don’t think Betelgeuse is ready to blow up. So what makes the researchers behind new paper think differently?
Related: The strange supergiant star Betelgeuse is glowing. Is it about to go supernova?
Betelgeuse is definitely a red giant with has burned off its main fuel hydrogen and is currently synthesizing helium in its core into heavier elements. The point at which a star runs out of hydrogen in its lifetime is unacceptable. Hydrogen-deficient stars need extra energy to ignite the helium produced during hydrogen fusion, forcing them to expand to tens of times their original size. In the process, they also become cooler and redder.
Astronomers know that Betelgeuse is huge. If it sat in our center solar systemThe gas burning in its outer atmosphere would reach far enough to engulf the entire planet Jupiter. However, the exact width of the Betelgeuse is difficult to measure. That’s because instead of being a fairly smooth ball of plasma, Betelgeuse is a mass of bubbles of boiling gas covered in clouds of escaped dust. Therefore, measuring its diameter is not easy, however, the case for determining the remaining lifetime of Betelgeuse is based on the size of the star.
In controversial new research, a team of astronomers led by Hideyuki Saio from Tohoku University in Japan suggests that Betelgeuse is larger than most researchers believe. This is possible because Betelgeuse is known to oscillate – expanding and contracting, dimming and lightening – at regular intervals. Most obviously, Betelgeuse’s luminosity fluctuates up and down every 420 days. Astronomers suggest that this brightening is due to the periodic expansion of the star’s crust, or quasi-spherical outer region, in a phenomenon known as the fundamental mode.
There are other quirks in Betelgeuse’s behavior, which also appear frequently, that astronomers attribute to additional turbulent processes taking place inside the dying star. One of those additional variations occurs on a 2,200-day cycle, and astronomers have no explanation for it. Thus, the Saio-led team proposed that this 2,200-day oscillation may, in fact, represent the primary Betelgeuse oscillation mode while the 420-day luminosity variation may be a minor factor.
However, such a scenario would require Betelgeuse to be up to a third wider for these evolutionary models to work, Saio told Space.com in an email.
«To interpret the 2,200-day period as the fundamental regime needs a much larger radius than the case that fits 420 days [period] with the basal mode,» Saio wrote in an email.
But for Betelgeuse to be as wide as the models claim, it would also have to be at a later stage in its life, having already burned off helium and running instead on carbon, which arose from the previous fusion of helium atoms. Whether a red giant is burning helium or carbon makes a big difference in how long it has left to live. The helium burning phase in the life of a red giant lasts tens of thousands of years. When carbon combustion is turned on, the end is near, cosmologically at least, and could come within a few thousand years.
“Although we cannot at present determine the exact amount of carbon remaining, our evolutionary models suggest that carbon depletion will occur in less than 300 years,” Saio writes. «After the depletion of carbon, the fusion of even heavier elements could happen in a few decades, and then the central part would collapse and a supernova explosion would occur.»
That will certainly be interesting for skywatchers. The last time a nearby star became a supernova was in 1604. Although the stars exploded somewhere in universe on a daily basis, most of them are too far away to be seen without powerful telescopes.
But the question remains: What else but models make Saio and his colleagues think Betelgeuse is bigger than other astronomers think?
In their paper, the researchers point to two measurements of Betelgeuse’s size to support their theory. But this is exactly where the paper has drawn criticism from other astronomers.
Miguel Montargès, a postdoctoral fellow at the Laboratory of Space and Instrumentation Research in Astrophysics at the Paris Observatory, who published papers on Betelgeuse based on his observations. Very large telescope in Chile, told Space.com in an earlier interview that «of Betelgeuse’s dozens of measurements, [Saio and his colleagues] can only choose two.»
László Molnár, an astronomer at the Konkoly Observatory in Budapest, Hungary who has also published several papers on Betelgeuse says that the measurements chosen by Saio and his colleagues to support the theory Their stars are likely affected by the clouds of dust and gas around that star. make Betelgeuse look bigger.
«If we look at the sun, we see a well-defined surface with very sharp edges,» Molnár told Space.com in an email. «But Betelgeuse is a red supergiant, extremely smooth and porous, and the photosphere, what we call its ‘surface’, is hidden beneath many layers of molecular gas and dust clouds.»
The violent expulsion of these materials is typical for red giant stars. In the case of Betelgeuse, astronomers observed such a massive cloud emerging from the star’s interior in 2019. make the star temporarily dim.
Molnár and his team made measurements of Betelgeuse’s size, which is more in line with what most scientists think.
The release of Saio’s paper coincided with Betelgeuse’s unusual glow leading some enthusiasts to speculate that the star might be about to explode. But neither Molnár nor Montargès were convinced. Betelgeuse, Montargès said, is actually too bright to be in a dying state due to the fact that the expulsion of matter often causes the old red giants to gradually fade away. In contrast, Betelgeuse, despite its regular pulsation, has been a fixed star of the ten brightest stars in our sky for at least the last 100 years.
The article has yet to be peer-reviewed and published, so some of its shortcomings may be addressed before it is officially released.
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