Neutron stars

Our universe is nothing different from a LEGO world. Each block, when put together, constitutes a complex object. However, each lego piece in our system is a combination of several other LEGO pieces. This network continues till we think we have reached the crux of the entire structure. One such level is the atom, consisting of protons, electrons, and neutrons. 

Neutrons are LEGO pieces that might not seem significant in the chemistry of our lives at first, but they do have an important underlying role. The atom consists of the negatively charged electrons revolving around the positively charged protons in the nucleus (with neutrons). The electromagnetic force between the electrons and protons prevents them from merging together. But the fusion is not always avoided…

Nuclear fusion is the process by which hydrogen forms the higher elements in the periodic table. This can only occur at temperatures higher than 100 million K. This environment can only be found in stars. Our sun and several other stars are fueled by hydrogen and helium. The fusion process goes on, helium combines to form carbon, carbon fuses to neon, neon to oxygen, and so on. As the ball of gas becomes devoid of helium, it nears its death, the size of the star gradually increasing along.

Once the massive stars start forming iron, the fusion process decelerates, since iron cannot be fused further. It is also termed as ‘nuclear ash’. Consequently, the gravitational force of the star pulls it inwards, resulting in its collapse. The outer layers of the sun get sucked towards the iron core. This occurs rapidly with a sudden drop in pressure, resulting in the explosion of the giant. This is scientifically called the ‘supernova’. Outer gas and material are spewed out in all directions, creating a magnificent display, being the brightest object in the surrounding. 

After the explosion, amidst all the matter, is present a small ball of nuclear material. The entire mass of the star is forced to a relatively smaller volume. The components of the atom are compelled to come together, due to the immense pressure generated by the collapse. The protons and electrons which, in normal circumstances would never synthesize together, now merge to form a neutron! The rest of the atoms remain closely bound together due to the compact size. This structure, consisting of atoms composed solely of neutrons, is called the neutron star!

Stellar objects of about 8 solar masses or more have the tendency to form black holes or neutron stars, while those like our sun eventually end their lives by turning into a white dwarf, made up of remnants of the core of the parent star. This happens when they run out of fuel (helium). 

The neutron stars are the most powerful objects in the vast universe after black holes. With a highly compact core, they span about 20 kilometers, covering less than half of Mumbai!

Unlike the size, it has a large gravitational force. If you take a grain of neutron star material, it would weigh a million tons. They are tiny but fatal. Due to this feature, it can bend light traveling near it, allowing you to see the objects present behind the star.

Neutron stars are extremely unique. They are not completely made of gas like other stars, but they have a crust! Neutron stars have an iron crust filled with a liquid core, just like all other planets but way denser, heavier, and smaller. This distinguishes them from the rest of the stars. 

After the supernova explosion, the neutron stars are seen to rotate rapidly. This is due to the leftover angular momentum of the parent star. Stars are continuously spinning, right from their birth. The speed, however, increases when they form the neutron star since it is smaller than its original size. Hence, it may emit jets of charged particles through its magnetic poles. It might do so, at regular intervals of seconds or even milliseconds. This pulsating, rapidly rotating neutron star is popularly called a pulsar.  

Another type of neutron star is called the magnetar. True to its name, the magnetic field of the star is quadrillion times stronger than that of earth, it is incomparable to any object in the universe. The crust of the star is bound to the field, creating tremendous amounts of pressure on it. Any slight deviation in the magnetic field may result in an explosion ejecting electromagnetic radiation.

Neutron stars may also occur in pairs with one another. Two neutron stars orbiting each other in a binary system form a ‘binary neutron star’. They may lose momentum by expelling radiation, energy as waves or ripples, etc, and merge into each other. This collision creates a kilonova. Conditions are such that higher elements start to form. Gold, platinum, uranium bismuth are a few of the many higher elements which are said to form during this kilonova explosion. We all are made up of star stuff and so is our jewelry! 

You might now have a fair understanding of how rare and exotic a neutron star is. Our universe is filled with wonders, waiting to be known. Neutron stars are one of them. 

Enjoyed reading this? Consider reading Star Clusters and their 2 types