The Magic of Nuclear Fusion and Gravity in Stars

A few days ago, we started to embark on our final chapter of Physics for the IGCSE curriculum- Nuclear Physics. As challenging as it sounds, Nuclear Physics is not as tough as it seems. After referring to the textbook and reading articles about the formation of stars, I have found out that the formation of stars are more closely related to Nuclear Physics than I initially thought it was.

The formation of stars involves nuclear fusion. Before this fusion even begins, gravity is needed to pull the materials needed to form a star- clouds of gases and dust. The simplified definition of nuclear fusion (gathered from the textbook and the internet) is the joining of two atomic nuclei to form a larger nucleus.

The baby steps to the formation of stars: 

• Gravity pulls dust and clouds of gases together.
• During this process, the volume of gases and dust increases, resulting to an increase in pressure.
• When the temperature is at its optimum, nuclear reactions begin. This is when nuclear fusion is added into the equation.

*From what we learnt in Physics, an increase in pressure results in an increase in temperature.

These nuclear reactions are what fuels the stars, keeping the star glowing hot. During nuclear fusion, a massive amount of energy is given out. The temperature of a star at this stage can easily reach 3000K to 4000K.

*3000K or 3000 Kelvins is equivalent to about 2726.85°C. 

Nuclear fusion in stars:

There are several complicated nuclear reactions that occur inside a star. However, the most frequently occurring reaction involves hydrogen nuclei joining to form helium nuclei.

The formation of helium through nuclear fusion.

Conditions inside a star which allows nuclear fusion to happen:

1. High pressure
2. High temperatures

All that you have read here is just the 'main sequence' of the star's life cycle. The star is stable at the main sequence of its life cycle as the forces acting on it (pressure from hot gases and gravity) are balanced. During the next blog post, we will explore what happens when all the hydrogen gases are used up and how mass affects a star. A star may form a black dwarf, or a black hole upon its death depending on its mass.

The life cycle of a star.

Sources:
http://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve/
http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/stars/lifecyclestarsrev1.shtml
http://abyss.uoregon.edu/~js/ast122/lectures/lec13.html
https://www.uwgb.edu/dutchs/AstronNotes/STARS.HTM

Thank you for reading
Joel