In October 2019, Betelgeuse, a red giant star from the constellation of Orion, suddenly dimmed. It proceeded to reach a new low in January and February 2020, getting to 40 percent of its natural brightness.
The information we currently have about Betelgeuse is that it is a mature star, which is on its way to exploding in a supernova… or not. The dimming incident has led to speculation about this explosion happening soon. Could that be true?
The dimming of Betelgeuse is not a complete surprise, as it is a so-called “variable” star, fluctuating in brightness over time. The variation is according to a 420-day cycle, and it now looks like the star is entering the brightening part of the cycle. Astronomers declare that even if Betelgeuse returns to standard parameters, questions will remain. That is because the dimming was a lot stronger than initially expected.
About Betelgeuse and its expected supernova transformation
If you replaced the Sun with Betelgeuse, it would swallow Mercury, Venus, Earth, Mars, and a part of Jupiter.
What causes a red giant to form is the depletion of hydrogen in the core of the star. When hydrogen can no longer be converted into helium via nuclear fusion, the core of the star begins contracting, and the internal temperature of the star rises, igniting a layer of hydrogen fusion enveloping the core, which in turn makes the outer layers of the sun grow bigger and cool down.
The core of Betelgeuse is hot enough that the helium present there is fusing into carbon. Once there is no more helium, heavier elements will be created, up to iron. Once that is reached, the star cannot generate energy anymore, and the core collapses. The outer layers of the star are next, hitting the core, which leads to an eventual explosion into a supernova. However, that won’t happen soon.