FLA: A Star is Born, literally

Like many stars, the source of the Sun’s light is the nuclear fusion reaction that occurs in its core. Hydrogen nuclei react with other Hydrogen nuclei to generate Helium—in process, releasing enormous radiation in form of heat and light. The temperature in the core of the Sun is, therefore, near 15 million Kelvin (27 million F). It takes about a hundred thousand years for this radiation to reach the surface of the sun, from where it reaches the Earth in 8 minutes, providing heat and light to the planet.

Hydrogen nuclei fuse to form Helium and liberate energy. Source: WJEC.co.uk

The process of nuclear fusion is what forces otherwise inactive elements to react with each other to form heavier elements. Nuclear collision and high pressure makes these reactions possible, thus creating heavier elements like Iron, Gold, etc. Iron is the most stable element. Past Iron, energy is now required to create further higher elements. This is possible only through supernova explosions. Given this, we can consider stars as chemical factories, liberating energy and light as a by-product of the chemical reactions. The process of fusion of atomic nuclei is known as nucleosynthesis.

Higher, heavier elements are formed. Source: LA Radioactive.com
Stars are chemical factories

The process of star formation is a quite inefficient process of combining gas clouds that could be the remnants of a dead star (e.g.: induced star formation). These gases collide and combine to trigger nuclear fusion thus forming stars. In the process, about 99.9% of the gas clouds are consumed, leaving the remainder for rocky or gaseous planets to form.

Depending on the mass of a star, its glorious life can end in two different stages. If the mass of a star is less than 1.4 times that of the Sun, which is also known as the Chandrasekhar limit, it collapses into a dense carbon-rich white dwarf. However, if the mass of a star is more than 1.4 times the Sun, it could either end up as a neutron star or a black hole depending on how massive it is. Further, for stars with high mass between 1.5 to 3 times the mass of the Sun, the main sequence stage is followed by a supergiant, leading to a supernova, and thus ending up as a dense neutron star. This neutron star is made up of dense neutron material, which is like a large atomic nucleus with an atomic number close to 1054. This star is the size of a small city, of about 10-20 km in diameter, with the density of trillions of grams per cubic meter.

Life and Death of a Star

If the mass of a star is more than three to five times that of the Sun, it is more likely to collapse into itself due to gravity and end up as a black hole. This end result is so dense that it compresses to a stage even smaller than an atom, known as singularity – the center of a black hole. The gravity of singularity is so strong that even light cannot escape from its field. This entrapment of light gives a sense of utter darkness surrounding it, the edge of which is known as the event horizon.

For the Love of Astronomy

My childhood love and passion for astronomy had its share of ebb and flow. While it peaked in 9th grade, when my friend and I ogled at images of deep space in our library encyclopedia, the zeal to pursue this passion was lost somewhere in the race for a “practical” education.

Fortunately, as my colleagues in the EPET program inspire me in different ways, my myriad disjointed conversations with them led to rekindling the remnants of some forgotten passions. One of the examples is how, with time, I got in tandem with pursuing an old interest in learning about astronomy.

From almost a year now, I have spent a handsome share of my leisure time reading about physics and astronomy. Recently, when I found a Cousera MOOC (Massive Open Online Course) on ‘Astronomy: Exploring Space and Time’ by Dr. Chris Impey, I jumped to the chance and enrolled myself for the nerdy fun I had waited for over 10 years.

pillars of creation - source es-static.us
Pillars of Creation

In this class, we look at the essential concepts in astronomy, physics, and chemistry that help understand the science behind some of most wonderful phenomena. The course requires some prior knowledge of the field–which reminds me to thank the turn-of-events that led to me choosing science and electrical engineering in school and college, respectively.

In the first two weeks, not only I have learned some of the most amazing facts and concepts that I had never understood before, I have also realized the profound importance of scientific literacy among general public.

Now, this course requires us to complete a bunch of tiny quizzes and three brief writing exercises. I think it would be a great idea for me to share these writing assignments on my blog here.

The next post is on Telescopes in Space. I will follow this introduction with this first writing exercise to share the fun that I am having in this course. I hope you enjoy reading this as much as I enjoyed the previous two weeks learning about