neutron stars

Neutron stars are city-size stellar objects with a mass about 1.4 times that of the sun. Out of every hundred stars in the Milky way, there is a star of Neutron type. The density of such stars is very high and the material inside squeezes itself together until it starts looking like one huge atomic nucleus. This is a strange atom as it is disproportionately built up of neutrons.

To comprehensively understand neutron stars effectively, let’s understand how intense gravity affects the personal space of every particle individually.

How Neutron stars are formed

A neutron star is basically the collapsed core of a very huge star which in general has a total mass of between 10 and 25 solar masses and it might increase if the star had a high metal quantity. Radius lies in the range of 10 km. The formation of neutron stars starts when the fuel of stars ends and they collapse. The central region of the star thus the core squeezes together each and every proton, electron, into neutrons.

Here is the whole process of the formation of Neutron stars

Various chemical reactions occur in continuation inside every star. Specifically, the nuclear reactions generate heat which then pushes out due to gravity pull resulting in a stable ball of plasma. Nuclear reactions cool down after some time. Heat loss makes the cooler gas sink fastly in the pull of gravity, creating shockwaves whose speed increases until it becomes a dense pile of hot iron which developed in its final formation time.

Huge energy generation occurs because of these shockwaves and thus hot radiation and gas are transformed into supernova explosions. In the end, balls of iron remain at the core having a weight a little heavier than the sun and constituting an atmosphere of captured hydrogen and helium. That ball is a Neutron star, with high gravity as if you go near it you will experience around 100 billion Gs of gravity.

What do Neutron stars hold inside it?

Strange physics is going everywhere around you and the same is the case for Neutron stars. High pressure makes the iron nuclei transform into a crystalline structure which is generalized by collecting infinite positive charges. A wave of electrons passes through gaps of this crystal and intense pressure brings them nearer to nuclei.

As per quantum physics, electrons have a high chance of residing inside a proton which makes the pair into a neutron and neutrino. Neutrons are subatomic particles with the same mass as protons but no charge on them while neutrinos are massless, neutral particles. Neutrino named itty-bitty is smaller in size but enough to clear off the mass. Opposite to this, neutrons continue to form weird isotopes with mass as that of iron but with fewer protons.

Atoms inside Neutron stars

If you dive deeper into the structure of neutron stars, the weight of neutrons will increase in such a way that they might start removing themselves from neutron stars. A rule says that in nature-identical particles can’t occupy the same space at the same time, which determines that neutron drift (a type of thick gas) is pushed apart under pressure. Around a kilometer inside a dead star, the ‘crust’ consists of neutron fog with few protons in some places.

Nuclei come up so close that they start rubbing each other. As gravity increases steadily specific arrangements start forming an atomic structure similar to that of pasta like spaghetti and lasagne which is then shaped by small repulsion and strong nuclear force.

In the core of neutron stars, physics continued to become weirder. Neutrons are forced into specific arrangements from such identities not following any previous laws thus setting strange currents. At the very center, gravity makes neutrons lose their individuality and become primary particles like quarks. Those quarks overlap one another and collapse at a point where humans can’t model it. Simply, it becomes a black hole.

How do Neutron stars die?

When a neutron star forms it continues to cool down by emitting radiation. Means it might not die ever and cool down for an infinite time. But it takes longer to cool down as neutron stars are born very hot. After all, they are just cores of large stars that are squeezed and heated during the collapse and have less surface area through which they radiate heat. Eventually, after a longer duration, you will be left with a cold neutron star emitting not much significant radiation but still called a neutron star.

Black Holes eating up Neutron Stars
An artist’s impression of a black hole swallowing a neutron star. Credit: Carl Knox, OzGrav-Swinburne University

 Following two ways can be the reason for neutron star death, ignoring its collision with a massive object.

– if a Neutron star is gathering material then it eventually passes the limiting mass and collapses.

– Neutron star usually born fast-rotating

 Neutron stars usually are born fast-rotating but that speed slows down due to the interaction of their magnetic field with the interstellar medium. Thus theoretically it is possible that they slow too much to stabilize it and the star collapses.

The collapse in both cases may lead to a black hole. Probably there can be an intermediate state between a black hole and a neutron star like the Quark star but we do not know much about it.


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