The expiration date of Betelgeuse, a massive dying star some 642 light-years from Earth, is a hot topic in astronomy due to the star’s superlative size and the stage of its life cycle.
Betelgeuse is between 10 and 20 times the mass of our Sun, with a radius about 900 times greater. It is burning fast and will soon (in cosmic terms) die.
When stars die, they expel most of their material out into the cosmos in a remarkable explosion called a supernova. If the conditions are right, the supernova leaves behind a serene stellar nebula.
Our own Sun will go through this process in about 5 billion years., but Betelgeuse is much, much closer to its end. And while the stars in the distant universe go supernova all the timeBetelgeuse is in our own galaxy, basically on our doorstep in cosmic terms.
Earlier this month, a team of researchers published a paper to arXiv prepress server. In the paper, the team posited that Betelgeuse is already in “the last stage of core carbon burning” and was therefore a strong candidate for our galaxy’s most imminent supernova. “Based on this figure, the core will collapse within a few tens of years after carbon depletion,” the researchers wrote.
on social networks, some interpreted this to mean that the supernova would occur in the next century, or even decades. But burning carbon is a slow process, even if Betelgeuse…that we are allowed to write as many times as we want without supernatural repercussions—is at that point.
In an email to Gizmodo, Hideyuki Saio, an astronomer at Tohoku University and lead author of the preliminary version, told Gizmodo that the team predicts that the supernova will occur in “less than a few hundred years.”
To some extent, the buzz around Saio the revised timeline falls victim to people not closely reading their team’s conclusion paper. But even so, scientists not affiliated with the research say the team’s model does not explain the star’s situation.
“It’s impossible for us to see what’s going on inside even our own Sun, let alone a star that’s hundreds of light-years away,” Emily Hunt, an astronomer at Universität Heidelberg who was not affiliated with the recent paper, said in a phone call to Gizmodo. “The fact that the model explains the observations does not mean that the model is correct.”
“It’s really bad that we’ve seen so many people take this article and take it as gospel, when really it’s just an interpretation of the observations,” Hunt added.
Betelgeuse is quite young—about 10 million years—but it will burn up much faster than the Sun. Throughout its evolution, Betelgeuse may have changed color in the night sky, which would explain why old descriptions of the star characterize the red ball of gas as more yellow.
In recent years, Betelgeuse has experienced an unusual amount of activity, sparking debates about when the fateful supernova might occur. In 2019, the star had a surface mass ejection, spewing around 400 billion times more mass from its surface than one of our Sun’s coronal mass ejections (CMEs). according to nasa.
The giant star dimmed substantially. The period is known as the Great Darkening. Astronomers now believe that the dimming was caused by a stellar belch that spewed dust from the star, partially obscuring Betelgeuse from sight
“It is unlikely that Betelgeuse is as evolved as they say,” said Miguel Montargès, an astronomer at the Sorbonne Université and co-author of a Article 2021 in Nature describing the dust that engulfs Betelgeuse, in an email to Gizmodo. “However, if Betelgeuse had a prior exchange of matter with a partner that is hidden within or near the star itself, or with a partner that died in the past, we could be looking at single-star evolution with many uncertain parameters. This would leave open the debate for its evolution”.
Montargès said the team’s model required a larger solar radius (about 1,300 sols long) than is observed (about 800 to 900 solar radii), and if Betelgeuse had shrunk as much as the team claims, astronomers would see material ceded from the star.
“I must emphasize that with our current knowledge, assuming the scenario of non-interacting stars and which we have no reason to rule out, Betelgeuse should be burning a helium nucleus and should explode in no less than tens of thousands of years,” Montargès added.
Unfortunately, the stage of Betelgeuse’s burning—that is, what element the star is currently using as fuel—is not apparent from observations. As stars progress through their life cycles, they burn different fuels (namely hydrogen and helium), with the burning of carbon occurring in the star’s death throes.
“One of the difficulties with this problem is that a carbon-burning Betelgeuse can look exactly like it does now, which is why this debate exists,” Meridith Joyce, an astronomer at the Konkoly Observatory in Hungary, said in an email to Gizmodo. “If it were easy to tell whether a star is burning helium or carbon just by observation, we might stop arguing!”
With two co-authors, Joyce posted a comment refuting the article by Saio’s team in the Research Notes of the American Astronomical Society. Joyce’s team posited that Saio’s team used an incorrect radius for Betelgeuse in making their claims, and the way they modeled the star ultimately produced an inaccurate (i.e., too early) timeline for Betelgeuse’s end.
“Our team argues that the time until Betelgeuse goes supernova is on the order of 100,000 years, a number that comes (mainly) from the helium burning condition,” Joyce added. “It wouldn’t be scientific to be more precise than that; there are too many unknowns in stellar modeling.”
Everyone agrees that more definitive measurements of Betelgeuse’s distance would be useful in determining the true brightness of the star, and therefore where it is in its life cycle.
Everyone wants to see a star die, which may be why people got excited about the “few tens of years” terminology in Saio et al. paper. When research finds that Betelgeuse will go supernova in a shorter period of time than predicted in previous papers, and the centuries-long time scales are pretty early in stellar terms, it will surely create more buzz than research that claims that Betelgeuse will go supernova. Betelgeuse still has a long way to go. .
But if you’re interested in seeing a supernova, you’d better look beyond our local supergiant. Montargès said that the stars eta Carinae and VY Canis Majoris (which the Minnesota Institute for Astrophysics calls “Betelgeuse on steroids”) are better bets for the next supernova in our galaxy.
Or you could always wait for space telescopes like Webb or Hubble to obtain images of its next supernova, somewhere in the most distant cosmos. Other telescopes, such as the The Rubin Observatory in Chile will soon be inaugurated— will aim to constantly image the night sky, hoping to capture fleeting events like the start of a supernova as they happen.
More: How do we know when the sun will die?