Betelgeuse’s Pulsations Hints at Near-Future Explosion


If you looked at Orion before it slipped behind the Sun this year, you might have noticed Betelgeuse shining unusually bright.

Astronomers have been puzzled by this increase in brightness, but a team has reexamined long-standing patterns in its variability.

They concluded that Betelgeuse is not only in the carbon-burning stage of its life but is also close to finishing this phase.

This means the red giant could go through the remaining stages of its life and explode within a few decades, possibly within the lifetime of readers today.

The Countdown to a Supernova

Betelgeuse, a highly evolved red supergiant, will eventually become a core collapse supernova, creating a light as bright as the full Moon.

While astronomically, this event is imminent, its occurrence on a human timescale is still debated.

Traditionally, it’s believed that Betelgeuse won’t explode for around 100,000 years, possibly frustrating many generations of astronomers.

Some evidence even suggests it could be a million years away.

However, a new paper, pending peer review, presents a different conclusion.

Image Credit: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella

The Life Stages of Betelgeuse

Stars like Betelgeuse start by fusing hydrogen into helium for most of their lives.

Once the hydrogen in their core is exhausted, they begin fusing helium into carbon, while hydrogen fusion continues in outer layers.

The process then moves to fusing carbon into neon, sodium, and magnesium, a stage known as carbon-burning.

Supernova explosions only occur after further rounds of neon, oxygen, and silicon fusion.

To predict Betelgeuse’s explosion, we need to determine its current stage.

According to Dr. Hideyuki Saio of Tohoku University and his co-authors, Betelgeuse is currently burning carbon and running out of it.

Pulsations and Predictions

Like other stars nearing the end of their lives, Betelgeuse pulses, swelling and shrinking, which causes changes in brightness.

These cycles have periods of 185, 230, 420, and 2,200 days, along with other unpredictable variations.

The great dimming of 2019-20 was partly due to an outburst of dust and the coincidence of several cycle troughs.

The study argues that the 2,200-day cycle is the radial fundamental mode (RFM), which is intrinsically related to the star’s radius.

If this is correct, Betelgeuse is larger than previously thought, possibly around 1,300 times the radius of the Sun.

For its mass, such a size suggests it is near the end of its carbon-burning phase.

Once this phase finishes, Betelgeuse could explode within a few decades.

Uncertainties and Excitement

Determining Betelgeuse’s exact size and distance is challenging.

It could be a very big star 530 lightyears away or an even larger one 900 lightyears away.

Despite these uncertainties, astronomers agree that Betelgeuse is nearing a critical point in its lifecycle.

While supernovas can cause significant damage to nearby planets, Betelgeuse is far enough away to be safe, yet close enough to offer an extraordinary view.

The last supernova in our galaxy was in 1604, and Betelgeuse’s explosion would provide a rare and spectacular astronomical event.

In conclusion, Betelgeuse’s pulsations and recent findings suggest that the star’s explosive end is not far off, potentially within the next few decades.

As we watch and wait, we might witness one of the most extraordinary events in the galaxy.