Neutron Stars4 min read

Our sun is 2* 10^30 kilograms in weight- over three hundred thousand times the weight of the earth. However, since the sun is so tremendous, its density is not overwhelmingly large. But neutron stars– star formed due to the gravitational collapse of a gargantuan star- are so unbelievably dense that a single teaspoon of a neutron star material would weigh about 10 million tons, or about the mass of a mountain! Neutron stars are one of the smaller specimens of astronomical objects- they are about 15-25 kilometers in diameter (about the size of a small city), as opposed to the one million kilometer diameter of our sun. However, a typical neutron star is around twice as heavy as the sun- it is like forcibly compressing twice the mass of the sun into a body about 50,000 smaller in diameter! Or, as described in Supernova Condensate, “take twice the mass of the Sun and compact it into the size of Los Angeles, and that’s roughly how dense a neutron star is”.

Neutron star

As defined by National Geographic, “neutron stars are ancient remnants of stars that have reached the end of their evolutionary journey through space and time”. Neutron stars are formed in the aftermath of the death of a massive star (over eight times the size of the sun- so the sun won’t form a neutron star, but a white dwarf instead); when this type of star collapses and explodes to create a supernova, it expels its outer layers such that only the compact, inner core remains. Moreover, due to their high density levels, the gravitational force is almost 2 billion times that on Earth- a force so strong that it can even bend the incoming radiation from another star (this process is known as “gravitational lensing”). This phenomenon is incredibly useful to scientists and astronomers, since it allows them to view the back of a celestial or astral body. So, we can see more than half of a neutron star at a given moment, due to the distortion and warping of light by the engulfing tidal forces.

In addition, it is due to this crushing gravity that the protons and electrons present in the star combine to form neutrinos and neutrons- hence the name “neutron star”. Furthermore, neutron stars possess such immense gravitational forces that any matter in their vicinity would instantly become “spagettified”- which is because this matter would be pulled toward this body at approximately 100 million kilometers per hour, or at almost 28,000 kilometers a second. An object can escape from the pull of this star only if it travels at at least one third of the speed of light! By contrast, the escape velocity of the earth is a mere 11.2 kilometers a second. However, when the mass of a neutron star exceeds three solar masses (mass limit, also known as the known as the Tolman-Oppenheimer-Volkoff limit), the star collapses inwards to form a black hole- from which even light cannot escape.

The structures of neutron stars are also very intriguing and unlike any other body in the cosmos- the surface temperature is about 1 million Kelvin (the sun’s temperature is 5,778 K), the surface is composed mainly of iron nuclei, and the 1 meter thick atmosphere is characterized by a crushingly strong magnetic field. In fact, as stated in Buzzle, the central core of a neutron star is “supposed to be a superconducting fluid of protons and electrons”.

Neutron stars are also known to rotate about their axes exceedingly fast, since the original stellar core had already been spinning. When still nascent, some neutron stars can spin up to sixty times in a single second, and some others can go up to 600 times per second. This high speed rotation results in the formation of a powerful magnetic field, which emits radio waves, visible light, X- rays, and gamma rays. All the same, at one point there will be no more nuclear fusion taking place inside the star, and it will subsequently lose energy due to a lack of internal energy generation. This is because the gravitational forces are stopped due to the heat created by the fusion of progressively heavier elements, until the core becomes extremely rich in iron- which is an element that cannot be fused further to generate energy. And since the core and the volume keep collapsing, the density and gravity keep increasing- thereby ultimately forming a black hole. At this point, the temperature of the neutron star can be almost 5 billion Kelvin.

All in all, neutron stars are one of the most interesting and thought-provoking objects in the universe. Although almost incomprehensible due to their properties and composition, neutron stars will always continue to serve as sources of enigma and mystique to humanity until eternity.

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