After the release of an unpublished study claiming the imminent supernova of the star Betelgeuse, there’s been a good amount of buzz surrounding the possibility of its life ending within our lifetime. From clickbaity Youtube videos to personal blogs to news publications, many have hyped up the notion of such an incredible astronomical event occurring in the near future. But is all this excitement warranted?
Betelgeuse is a supergiant star over twenty times larger than our sun, approximately 640 light years away from us. Bright red in coloration, it is the ninth brightest star in the night sky (the first being Sirius). It can be seen in the constellation Orion, located in the figure’s “shoulder”.
A supernova occurs when a star burns through the last of the fuel within its core. Once out of this fuel, a star rapidly begins to cool, causing a pressure drop resulting in the star collapsing under its own weight. If a star is not massive enough, a supernova will not occur, instead shrinking down into a white dwarf and eventually dying quietly. This is the fate awaiting our sun (in a few billion years, of course). But if you have a star at least five times larger than our sun, it will go supernova, the speed and force of the collapse creating an explosion. What’s left of the star, an incredibly dense core, may become a black hole. Considering Betelgeuse’s immense size, there’s no doubt that when it goes out, it’s going out with quite the bang.
The consensus is that Betelgeuse is nearing, if not already at, the end of its carbon burning phase and is currently cooling.
Back in December of 2019, a ‘Great Dimming’ occurred, where the supergiant’s brightness dropped by a factor of approximately 2.5 times from its dimmest recorded shine, before returning to its regular luminosity by early 2020. The star itself did not lose and regain that brightness; the drop was caused by a cloud of ejecta from Betelgeuse’s surface. The current popular theory among scientists is that the dust cloud was formed by a cool spot on Betelgeuse. Said cool spot created a gas bubble that popped, and the debris released from it made a dust plume large enough to partially obscure a star over 760 million miles in diameter.
Considering its sheer size and the fact that it is a celestial object, the exact amount of helium Betelgeuse has left would be hard to pin down. That’s where Hideyuki Saio of Tohoku University comes in, with a study that’s been… controversial, to say the least.
Saio and his team came forth in June with this paper uploaded to arXiv, claiming that the red star’s demise will occur in “a few tens of years”. This news would be exciting for astronomers and casual observers alike. A supernova has not been visible from Earth since 1604, so the opportunity to see one with the naked eye would be a once-in-a-lifetime opportunity that wouldn’t occur again for hundreds of years. But unfortunately for us, the scientific consensus seems to favor Betelgeuse outliving us.
While, yes, Betelgeuse is cooling off and will go supernova soon, in astronomical terms “soon” can mean upwards of hundreds of years, just like how Betelgeuse being “close by”us means it’s within one thousand light years. The current estimate for the explosion is ~300 years (though some sources estimate over 10,000), longer than any of us will be around for. Many astronomers claim Saio’s study is over-exaggerating how close the star’s death is. As Miguel Montargés of the Paris Observatory, who specializes in red giants, puts it in an interview with Space.com, “of the tens of measurements of Betelgeuse, [Saio and his colleagues] have selected only two”. Measurements of Betelgeuse used in Saio’s study place the star as even larger than what most astronomers agree on.
Saio’s study still has yet to be peer-reviewed and published, but as of now in order for its estimates to be correct, Betelgeuse would have to be a good bit bigger than we think it is. Though the study’s lack of credibility is disappointing for those of us who were looking forward to such a spectacle, there’s still plenty of upcoming astronomical events to be excited about. For example, across North America, this month, on October 14th, an annular solar eclipse was visible in part or full depending on where you are. In this eclipse, the moon partially covered the sun. This was the last eclipse of its kind visible from the continental United States until 2044.