Neutron Star: The densest star
Densest Star :
Dying of Stars –
Everything in this universe was born are subjected to death. Even stars are not eternal. But in human eyes, it looks like stars are eternal. Because being human we live a tiny life compared to Stellar objects.
Life of a star depends on its mass. High mass stars have high in hydrogen fuel. Therefore, they have a long life. And low mass stars have low in hydrogen fuel. So they have a shorter life.
When a star runs out of its fuel it could be transit into a White Dwarf or Neutron star or black hole. A low mass star transits into a white dwarf. And a high mass star into a black hole. But between them, a neutron star comes into existence.
What is a ‘Neutron Star’ –
Stars start to generate energy by fusion of simplest hydrogen atom and produce helium through their life that keep them shining. If the star big enough then its own gravity produces enormous heat in the core, That enables further fusion process to continue. And respectively make heavier element like carbon, neon, oxygen etc. But in some point, the star will not be able for further fusion process. And the stellar evolution comes to an end. And the star died. Thus smaller star from the end of its life to as a white dwarf. Which takes billions of years to cool down. Because though they have ended up their fusion process its remains a very high temperature. This will happen to our Sun. Because the Sun is a lower mass star. For the really big star with the end of fusion enable gravity to breaks down its particle. And squeezes together as much as nature will allow and forms a black hole. And in between white dwarf and black holes the neutron stars formed from medium weigh stars.
How Neutron Star Forms –
As the star evolves away from the main sequence, subsequent nuclear burning produces an iron-rich core. Now when all nuclear fuel exhausted and the core stable against gravity only by electron degeneracy further deposits of mass from shell burning cause the core to exceed ‘Chandrasekhar limit‘. Here gravity overcome the electron degeneracy pressure. And the core collapses further, that raised the temperatures soaring to over 5 × 10^9 Kelvin. At this temperature photo disintegration occurs. That is to say, the iron nuclei break up into alpha particles by high energy gamma rays. As the temperature climbs even higher, remaining protons and electrons in the star combine to form neutrons. And release a flood of neutrinos in space. When its density reaches 4 × 10^17 kg/m^3 the in-falling outer layer of the star is halted and flung outwards by a flux of neutrinos and burst into a Supernova. The remnant left is only a core of neutron and a neutron star is formed. If the remnant has enough mass about 3x solar mass then it collapses further to form a black hole.
Mass/Gravity of Neutron Star –
A neutron star perhaps has a mass of 1.39 to 3 solar mass. It has a magnetic field range between (10^4 to 10^11 Tesla), where the magnitude of Earth is (25 to 65 micro Tesla). Though a neutron star has a (1.4 to 3) solar mass but it roughly compressed to an object of 10 to 25 kilometer wide. It is so dense that 1cm^3 contain 1 billion tonnes. It has a gravity that also very impressive too. If we drop an object from the 1-meter height on neutron star surface it will hit the surface in 1 microsecond and accelerate up to 7200000 km/h. Its surface temperature is about 1 million Kelvin. Neutron stars spin very fast, several times per second. And if there is any co-star to feed, then it spins several 100 times per second. It could spin at 1/4 speed of light.
Pulsar star –
A teaspoon of mass from ‘Neutron Star’ weighed more than our Everest. And a ball about 15 miles across contain more than the mass of our Sun. Neutron stars spin 7000 to 14,000 times a minute and forms an incredibly intense magnetic field. Rapid speed and powerful magnetic fields spread powerful electromagnetic radiation, including gamma rays in space. And this type of neutron star is called Pulsar. As the pulsar rotates, light sweeps in the sky like a lighthouse, and to distance observer the Pulsar appears like blink on and off…
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