Life-cycle of a Star

Do you ever wonder where did our Sun come from? How long will it keep shining up there?. And what happens in the final moments of the stars that we see as we look up at the night sky.?

The life of a star begins inside a Nebula which is a huge mixture of gas and cosmic dust spread across the vast space. Inside this nebula, Hydrogen gas begins to accumulate due to the forces of gravity and starts spinning. Over time, it generates an immense amount of heat as the gas spins faster and faster. This heat then results in nuclear fusion to take place inside the core of this gas cloud. This is when it begins to glow. Like our star in the middle of our solar system does.   

But how long will it keep glowing? As long as there is enough hydrogen at the core of the star, which is constantly being converted into Helium by the process of nuclear fusion. (Our Sun has about 5 billion years of Hydrogen fuel left inside its core. So we are safe till then!) Once this hydrogen fuel runs out and the process of generating Helium stops, the core of the star becomes unstable. At this point, the star begins to expand outwards and starts glowing red as it cools down, famously known as Red Giant. (When our Sun turns into a Red Giant, it may swallow its nearest planets, Mercury, Venus, and Earth as well. We don’t want to be on this planet to see it happening.) The process of nuclear fusion at the Red Giant star’s core still persists, only this time the Helium is being converted into carbon.

The star will go through the next phase of its life depending on its mass. once the helium fuel runs out at the core of a Red Giant, a Low-mass star like our Sun collapses into a white dwarf, which is a very small and incredibly dense object. This collapse shoots out the glowing ionized gas of outer layers of Red Giant creating a Planetary Nebula (Slightly less awesome, than what happens with the massive stars.). 

When Massive star runs out of Helium fuel in its Red Giant phase, it undergoes a supernova explosion. The explosion occurs due to the nuclei of atoms being crushed up to a point where repulsive forces at the atomic levels overcome the forces of gravity and a shock wave is released from the core seen as a supernova explosion. (fun fact: the brightest of these explosions can outshine a galaxy in which it took place). The star will now turn into a neutron star if the mass of the remaining matter is about 1.4 to 3 times as massive as our Sun. If the core is even more massive than this, The forces of gravity overcome the repulsive forces at the atomic levels and the star turn into a Black Hole (A singular point of theoretically infinite density with an immense gravitational force).

What is Nuclear fusion?

The Process where smaller nuclei combine into larger nuclei having lesser mass than the sum of the parent smaller nuclei. This remaining mass is converted into energy governed by Einstein’s famous equation: E = mc2.

I wonder where will humanity be when our sun is about to explode. Will we be able to find a good spot in the universe to look at this event where our Sun creates a beautiful Planetary Nebula?