Neutron Stars

Neutron stars are extremely dense remnants of massive stars that have undergone supernova explosions, and they typically possess strong magnetic fields and rapid rotation. The Hertzsprung-Russell (HR) diagram primarily charts stars based on their luminosity and temperature, focusing on the main sequence, giants, and white dwarfs. Neutron stars are not in thermal equilibrium like those stars, as they emit energy primarily through processes like thermal radiation and magnetic field interactions rather than nuclear fusion, which is why they do not appear on the HR diagram. Instead, they are often represented separately in discussions of stellar evolution and compact objects.

Well my friend, neutron stars are really compact and super dense, about the size of a small city or around 12 miles (19 kilometers) in diameter. To put it in simpler terms, a neutron star is about the size of Manhattan in New York City compared to the vast size of our beautiful Earth. Just imagine a tiny speck among the grand colossal canvas of the universe.

Well, isn't that a fascinating question. The surface gravity of a neutron star is incredibly strong, many billions of times stronger than Earth's gravity. It's like trying to hold on to a massive bouquet of happy little clouds!

A neutron star is what is left of the core of a massive star after it dies. The core collapses under the force of gravity, crushing itself from a size far larger than Earth to about the size of a city but still with a mass up to 3 times that of the sun. If it is any more massive it becomes a black hole.

A neutron star has slightly more mass than a white dwarf. This results in higher gravitational attraction. As a result, in a white dwarf, the star's mass (roughly the mass of the Sun - may vary in different white dwarves) has a diameter of a few thousand kilometers, and a density of a few tonnes per cubic centimeter. The neutron star, on the other hand, has a diameter of only 20-30 kilometers, and a density of millions of tonnes per cubic centimeter. For comparison, water has a density of 1 gram per cubic centimeter, other substances around us have similar densities; so the density of a white dwarf is millions of times the density of water, while a neutron star has billions of times the density of water.

The LIGO (Laser Interferometer Gravitational-Wave Observatory) and Virgo observatories are used to detect gravitational waves produced by the collision of neutron stars. These observatories are equipped with detectors that can measure the tiny ripples in spacetime caused by such cataclysmic events, providing valuable insights into the nature of the universe.

Down to something called the Avogadro Constant. It states that 1 mole of ANY gas will always occupy the same amount of space.

A pulsar is a special kind of neutron star, which is the ultra-dense leftover core of a massive star. Pulsars emit beams of radiation that sweep out in circles as the pulsar spins. When those beams flash over Earth, we see them as regular, repeating pulses of radio emission.

A subgiant star is larger than a neutron star. Neutron stars are incredibly dense and compact remnants of massive stars, while subgiant stars are in a transitional phase between main sequence and red giant stages, typically larger and more diffuse than neutron stars.

A subgiant star is bigger than a neutron star. Neutron stars are incredibly dense and compact, with a radius of about 10-15 kilometers, while subgiant stars have a larger radius of several million kilometers.

When the gravity of a massive star overcomes neutron degeneracy pressure, it can result in the star collapsing further to form a black hole. This occurs when the mass of the star is above a certain threshold known as the Tolman–Oppenheimer–Volkoff limit, causing the neutron degeneracy pressure to be insufficient to support the star against gravity.

Neutron stars can appear in various colors, including white, blue, or red, depending on their temperature. Pulsars, which are rapidly rotating neutron stars, can emit radiation across the electromagnetic spectrum, including visible light, X-rays, and gamma rays. So, their color can also vary depending on the type of radiation being emitted.

when a supernova occurs and the star is destroyed but if some how the nucleus survives and its mass is 1.4 solar masses then the nucleus started to shrink under its own gravity then the next stable state is neutron star.

Your weight depends on your mass and the strength of the gravity where you are. A neutron star has a mass 2-3 times that of the sun compacted into a very small area, resulting in a surface gravity billions of times stronger than on Earth. As a result, at the surface of a neutron star you would weigh several billion times what you do now.

Saving the full explanation of the processes of a star, just a short rundown: Stars are massive, so massive that their own gravity tries to collapse the star so it has to fuse hydrogen to exert an outward force to overcome its own gravity. During these processes, atoms are being stripped apart into free-floating nuclei, electrons and protons, accumulating in the core for the life of the star. When a star runs out of hydrogen fuel, it collapses and is stopped by the core getting hot enough to fuse helium (Product of hydrogen fusion), and that keeps happening up the atomic chain until the star starts fusing nickel, which requires more energy to fuse than is released, this is the end of a star as we know it.

If a star forms a black hole or a neutron star is dependant completely on the star's mass. If it is heavy enough, if will become a black hole, if not, then it will become a neutron star, where gravitational collapse is halted by the accumulated electrons in the core being compressed with free protons, bonding together to form neutron degenerate matter (Basically neutrons) and exerting an outward force that overcomes collapse. This force is known as neutron degeneracy pressure, courtesy of the Pauli exclusion principle of the Fermi-Dirac statistics. The principle states that no two fermions (Particles with a half-integer spin; quarks and leptons) can occupy the same energy state simultaneously, so you get an outward force.

Now if gravity were to overcome said force, the neutrons would then split into their individual quarks, resulting in quark degenerate matter and halting collapse, although very little is known about quark degeneracy or even how the matter splits into quarks. Then into the hypothetical preon degenerate matter and finally a gravitational singularity. Please note that very little is known about quark and preon degeneracy (The latter being generally not accepted as a viable model) as none have been discovered to date.

Finally, if the star wasn't heavy enough to form a neutron star, the core will decay into a large and hot ball of iron (Nickel decays into iron) and float, slowly cooling for the remainder of its existance or until acted upon by external forces.

It would not exist. A neutron star is what it is by virtue of the mass of the whole star. Extracting just a pinhead would revert that matter back to normal matter.

For the sake of density - as weight has nothing to do with matter outside of a gravitational body.

The denisty of a pinhead of neutron star would be the equivalant of about 100 times the mass of the Great Pyramid of Giza

It's pretty complicated, and we really don't know what the core is actually like... some astrophysicists think it's mostly neutrons (hence the name "neutron star"), while others think it might be some kind of weird degenerate strange matter (a kind of quark fluid made of up, down, and strange quarks).

The average density of a neutron star with the same mass as the sun would be about 1 x 10^17 kg/m^3. Neutron stars are incredibly dense objects, as they are formed from the remnants of massive stars that have undergone supernova explosions.

White dwarfs are prevented from collapsing further by electron degeneracy pressure. If the mass of a stellar remnant exceeds the Chandrasekhar limit, about 1.4 solar masses, gravity will overcome this pressure and form a much smaller and denser neutron star. Further collapse in a neutron star is prevented by neutron degeneracy pressure up until the Tolman-Oppenheimer-Volkoff limit of about 3 solar masses, at which point gravity causes a complete collapse, forming a black hole.

Of course you can, that is how we know they exist.

However you will need a telescope designed to look in the x-ray range of the electromagnetic spectrum, since neutron stars do not emit much of their energy in the visible range.

The mass of a typical neutron star is believed to be between one and three times the mass of the sun. However, in size they would be much smaller than the earth, something on the order of around ten kilometers in diameter.

Supernova explosions are responsible for producing elements with atomic masses greater than iron through nucleosynthesis processes. During these violent events, heavy elements are forged from lighter elements through rapid fusion reactions.