When will Betelgeuse explode? Controversial New Study Says “Soon”

We’ve all resigned ourselves to not seeing Betelgeuse explode, but at least one team of astronomers is still hopeful.

If we’re going to see a nearby supernova, Betelgeuse, the bright red giant on the right shoulder of the constellation Orion, is our best chance. But despite taunting us until early 2020, once again with its recent brightness, the star stubbornly refuses to explode. Most recent studies agree that a Betelgeuse supernova will not occur in our lifetime, but one team of astronomers suggests that it could actually happen in the next few decades.

It all depends on how big Betelgeuse actually is.

Where’s the Earthshatter Kaboom?

Ask an astrophysicist, and they’ll probably tell you that right now, in the center of Betelgeuse, enormous heat and pressure are fusing helium atoms together into carbon atoms. If so, the giant star has several more phases – and many thousands of years – to go through before it finally fuses the last silicon atom into iron, burns itself out, and collapses under its enormous weight, producing an extremely powerful explosion. It will be visible from other galaxies.

But in a recent preprint study (not yet reviewed and published), an astronomer from Tohoku University Hideyuki Sayo Instead, he and his colleagues suggest that the star is already nearly finished burning carbon — after that, it will only take a few decades for it to pass through oxygen and silicon. Sayo and his colleagues base their claim on the number of times a star pulsates, or brightens and dims.

Betelgeuse has a history of beating on regular cycles, like a beating heart on a cosmic scale. The cycle that astrophysicists consider the most important takes 420 days to dim and light again. During those 420 days, the entire interior of the star is simultaneously expanding and contracting (this is called a radial pulse). Two other shorter glow-and-dark cycles are the so-called hypercolor modes; Different layers of the star pulsate in opposite cycles but at the same time, so one layer contracts while the next expands.

“These pulses are self-excited in Betelgeuse because of the instability of the energy flow there,” says Sayo. inverse.

The astronomers also noticed a much longer cycle of brightening and dimming coming from Betelgeuse, a cycle that takes about 2,200 days — more of a “slow ripple,” the astronomer says. Laszlo Molnar, of the Kokoli Observatory in Hungary, and colleagues describe it. Most astronomers assumed that this longer cycle was not part of a so-called radial pulse, but instead caused by something outside the star, such as nearby dust. This is a very common phenomenon in red giants and supergiants such as Betelgeuse.

On the other hand, Sayo and his colleagues say that the 2,200-day cycle is actually the main period of radial pulsation in Betelgeuse, when the entire star expands and contracts simultaneously.

Thanks to the physics of how stars function, if Betelgeuse pulsates on this long cycle, it must have a larger radius than most astronomers think: about 1,300 or 1,400 times that of our Sun, compared to previous estimates of 600 or 1,000 times the radius of our Sun.

Based on the computer models, Sayo says, “we found that the evolutionary stage of the model with such a large radius must be at a late stage of carbon combustion.” If Saio and his cohorts are right, Betelgeuse could explode in the next several decades.

In fact, size matters

But according to other astronomers, this is a big “if”.

“They assume a much larger radius than what was observed,” said the Harvard astrophysicist. Andrea Dupree Tells inverse.

Molnar and colleagues make the same point in their recent counterargument to Sayo and colleagues, which they publish in Research notes of the American Astronomical Society. Telescopes have spotted Betelgeuse in several wavelengths of light, and according to Molnar and his colleagues, all of this data rules out that Betelgeuse is more than 1,100 times the size of our Sun — not big enough to pulse the entire star on this huge, slow 2,200-day cycle.

In other words, the data telescopes around the world (and in orbit) have accumulated over the years do not indicate that Betelgeuse is large enough or old enough to explode anytime soon.

“The star is going to go supernova,” Dupree says. inverse“But not in our life.”

Maybe if we said her name three times it might speed things up. What’s the worst that could happen?