Betel gurtz, or bug juice, has been a favorite among amateur astronomers for years. No matter how you pronounce it, its sudden dimming is drawing even more attention to this red supergiant variable star in Orion. It has several cycles of variability, one of which lasts 2,170 days, five times longer than its normal pulse period. A paper was recently published suggesting that a star with a mass of 1.17 solar masses may be responsible.

This would require an orbit about 2.43 times the radius of Betelgeuse, and could result in modulation of the dust in the region, causing the changes we see. One of the brightest stars in the sky, Betelgeuse is a red supergiant located in the upper left of the constellation Orion. It represents the hunter’s shoulder, although some translations suggest it means “giant’s armpit.”

With a radius of about 1,000 times that of the Sun, it is one of the largest stars visible to the naked eye. Its brightness in the sky at a distance of 642 light years tells us that it must emit about 100,000 times more light than the Sun.

It has received special attention in the last five years because of an unexpected eclipse.

A terrestrial view of the constellation Orion. The Hubble Space Telescope continues to reveal a variety of stunning and intricate treasures in a nearby region of intense star formation known as the Great Nebula in Orion.

The outage occurred in late 2019 and returned to normal in the first half of 2020. It is generally believed that the blackout was caused by a dust cloud from an event now known as the Great Eclipse.

The light curve of Betelgeuse, a well-known variable star, exhibits a long secondary period (LSP) of about 2100 days. This is not unusual for stars in the red giant branch of the Hertzsprung–Russell diagram and can vary from a few hundred days to thousands of days.

However, the mechanism behind the LSP is currently unknown, but it certainly appears to be a secondary cycle to the shorter one. Interestingly, the period of the LSP is usually tens of times slower than the radial pulsation of the stars.

The nature of this long-term Betelgeuse variability is the subject of a new paper by Jared A. Goldberg and his team. Further understanding will lead to a clearer understanding of Betelgeuse’s evolutionary stage and ultimately its demise.

One solution suggests that this is simply the result of the outer layers vibrating. If this is the case, this would mean that Betelgeuse is larger than expected and further along its evolutionary branch, and that a supernova explosion could be imminent within the next few hundred years!

Interestingly, the team concluded that the most likely explanation for Betelgeuse’s long-term variability is a low-mass companion star called Ori B (Betelgeuse’s alternative name is Orion).

It is possible that this binary star could modulate the dust surrounding the system, causing the dust to dim as the companion moves. If Ori B is confirmed, it would have a significant impact on our understanding of Betelgeuse’s evolution.

It is expected to go supernova soon, but that is largely because the observed changes have led us to conclude that it is imminent. Instead, Ori B’s cause means we may have to wait a bit.