On the verge of its life :Betelgeuse

In the vast expanse of space, there are numerous mysteries. For instance, what is inside the black holes? Why is the universe expanding? How will everything end? Another such mystery is the fate of the various types of stars. Betelgeuse, a red supergiant, is one such star which deserves special attention. 

But, what exactly is a red giant? Basically, it is a star that is at its last final stages of stellar evolution, and has a weak atmosphere; hence, it expands at exponential rates. An average red giant has a surface temperature of approximately 4700°C. Mainly, there are seven types (categorized as different numbers) of stars, which are classified as types O, B, A, F, G, K and M—from hottest to coldest. The types O and B are the brightest and hottest; Sun is a G type star. As for red giants, they can be of any size; from 30% of solar mass to 8x solar masses. 

The stars of categories K and M are most likely to become red giants at the last stages of their lives.

Now, how does a red giant initially form? It happens when a star— approximately the size of our Sun— burns up all its hydrogen, with the passage of time. Afterwards, the star starts to collapse due to its own gravitational pull. This happens till its helium, formed due to fusion of hydrogen atoms, starts to make carbon. With that, the star has the aid of a carbon/hydrogen-driven chemical process, which it uses as a new fuel. Because of this process, the energy released pushes out the outermost layer of the star, and helps prevent the star from collapsing soon. This is the start of the formation of a red giant. 

But, what is so special about Betelgeuse? First, it is large, in fact super massive, or roughly 950 times larger than the Sun. Not surprisingly, it is among the brightest stars in the night view. It is predicted in many scientific researches that since the Betelgeuse is in the last stages of its life, it can become a supernova anytime now, which could be either today, or in the next million years! But first, what is a supernova? Well, to explain simply, ‘A supernova is a large explosion that takes place at the end of a star's life cycle’. It is, indeed, a catastrophic event.

As reported in many articles, the Betelgeuse is ‘acting strange’. It is mainly because of its ‘noticeable’ dimming, which has captivated many scientists and astronomers. This can be the sign of a possible supernova in the near-to-distant future. 

Back to Betelgeuse: Situated 641.4 light years away from us, its mass is 2.188 × 1031 kilograms.  How big are these numbers? Well, one Betelgeuse is equivalent (in terms of volume) to 950 suns, which is HUGE! Also, it emits 7,500 times as much energy as that of the Sun in one second, and its mass is 12 times more than our Sun.

What if we had Betelgeuse in our solar system? Well, it would engulf the orbits of the following planets (and Asteroid belt): Mercury, Venus, Earth, Mars and Jupiter. 

Now, imagine what would happen if Betelgeuse explodes today: Well, if a supernova is close enough to Earth, it can send high energy gamma rays (the radiation) to earth which are extremely dangerous to life. A supernova about 2.7 million years ago caused a ‘mass extinction’ on Earth. Coming back to that disastrous supernova, it caused—or contributed—to mass extinction about 450 million years ago, during the end-Ordovician extinction.

Wondering what mass extinction is? In actuality, it means that most of life goes extinct, but not entirely all. Further, it is very difficult to wipe out all life on Earth, especially microscope life, which is quite resistant to dying in harsh conditions. 

Anyways, now I come to the question of how will the Betelgeuse supernova look like in our skies? It will be immensely bright. It will be the third brightest object in the sky, and will easily be visible in the dayskies’ as well. In fact, it will look like another moon, albeit half one, and will likely stay in the sky for a few weeks before it starts losing its luminosity. The supernova would be easily visible in all parts of the planet. 

I stargaze every night. Each star. Each constellation. Each astronomical body. With great interest and keenness. Including that of Betelgeuse, which will always have a special place in them. Realizing that it is about to explode into a supernova anytime now, I feel mixed emotions; both disappointment and excitement. Finally, as the great astronomer Carl Sagan says, ‘somewhere, something incredible is waiting to be known’.