Betelgeuse

Okay, I am really obsessed with the giant stars.🤷‍♀️

One of the nearest giant stars with about 600-700 light-years, Betelgeuse, is a star at the end of its life and reached its red giant phase. Betelgeuse, which can be visible in the sky, even in large cities at night, is highly sized with a diameter reaching 1,000 times the sun.

The star's mass is about 15 times greater than our Sun and was born about 8 million years ago.

The lifespan of such giant stars is very short. Considering that our Sun is about 5 billion years old now, you can understand how short this period is. In other words, as the dinosaurs roamed the earth, Betelgeuse did not exist in the sky; it had not yet formed.

Well, more than 90% of the stars you see in the sky today with the "naked eye" did not exist then. The sky was still full of stars, but only a few stars were familiar, like Sirius, Alpha Centauri. Most of them died and were replaced by new ones like Betelgeuse (because all but a few of the stars we can see with the naked eye are short-lived giant stars).

Let's get into details. 😉

Our Sun produces energy by converting the hydrogen in its core to helium. (You can remember from my blog post about the white dwarf )

On the other hand, Betelgeuse has already finished burning the hydrogen in its core to helium, and currently, it transforms the helium into elements such as carbon and oxygen. Since these elements' nuclear reactions produce much more energy than hydrogen, the star has expanded like a balloon and reached its current gigantic size. Cool, right? 😎

Due to the surface area expansion caused by swelling, the star's surface temperature is about 3,200 degrees Celsius. This high energy release causes the star to inflate, and its outer layers gradually escape gravity to spread into space and form a cloud of fog around the star. This is how it lost most of its original mass.

The star, which rapidly accumulates iron in its core by nuclear reaction with helium, oxygen, and carbon, is close to the end of its life. Iron cannot form other elements by combining them like other elements. For this to happen, it needs energy from the outside. So, after a while, the star's core will be made entirely of iron, and energy production will cease. When this happens, there will be no radiation pressure to keep Betelgeuse from collapsing. Therefore, the star will collapse into itself at great speed.

Supernova

This collapse is the source of the "external energy" that iron needs. This energy created by gravity will suddenly cause the iron core to overheat and compress enormously, and a very violent nuclear reaction will occur. Iron atoms in the nucleus transform into heavier elements such as nickel, copper, zinc, silver, mercury, and gold. And this is called a supernova explosion.

We don't know when this supernova explosion will occur. It could be the next year, or it could be 100,000 years from now. Although all these periods are considered "tomorrow" on the astronomical scale, it seems like an eternity for our short lives.

How we see it

When the explosion occurs, Betelgeuse will look like a magnificent star with enormous luminosity from the earth.

It will be so bright that it will provide a light that can be easily observed even during the day and cast shadows on objects such as the Moon at night. This will keep its very bright state for a maximum of 10 days. Afterward, it will fade slowly and disappear entirely within one month, and never be seen again.

Meanwhile, no worries, nothing will happen to us. No radiation, no star crushes. Just an amazing light show 😎 If you are lucky to see of course 🤞