Life of Stars - The Birth

  

 

After the big bang for millions of years, the universe comprised mostly of helium and hydrogen. Darkness prevailed in this infant universe. There was no light in this universe, until the first stars were formed. In this blog, we'll talk about the life cycle of stars. In subsequent blogs we'll talk about black holes, and other mysterious objects in the universe.

 The carina nebula, huge clouds which give rise to stars

For millions of years the universe was enveloped in darkness with huge clouds of dust and gas forming and continuously expanding. These clouds grew to become so massive with significant mass that their force of gravity eventually caused it to collapse into itself. It shrunk to form a extremely hot dense core with disks of matter spinning around it. As the cloud collapses, a dense, hot core forms and begins gathering dust and gas.

Eventually, the core became so hot reaching approximately 15 million degrees, the particles of dust and gas got so close together that they stuck together and fused. This fusion resulted in a great surge of energy, and the core of the gas ignited with a release of heat and light to become a glowing ball called a star, while the disc of matter, that was originally circling around it, dispersed into space to form planets, asteroids etc. This star is now powered, and glows by the nuclear fusion occurring in its core.

So what is this magical thing called “nuclear fusion” and why does it start happening inside the ball of gas and dust? It happens like this..... As the contraction of the gas and dust progresses and the temperature reaches 15 million degrees or so, the pressure at the center of the ball becomes enormous. The electrons are stripped off of their parent atoms, creating a plasma. The contraction continues and the nuclei in the plasma start moving faster and faster. Eventually, they approach each other so fast that they overcome the electrical repulsion that exists between their protons. The nuclei crash into each other so hard that they stick together, or fuse. In doing so, they give off a great deal of energy. This energy from fusion pours out from the core, setting up an outward pressure in the gas around it that balances the inward pull of gravity in the star which we'll elaborate on later. When the released energy reaches the outer layers of the ball of gas and dust, it moves off into space in the form of electromagnetic radiation. The ball, now a star, begins to shine. 

What happens after this completely depends on the mass of the star. There are three types of stars that can be formed by the during the above process : small stars (quarter the size of our sun), medium stars (like our sun), and massive stars (eight times the mass of our sun).

In the next blog, we will discuss the life and death of these stars as well as the formation of back holes and neutron stars...