Neutron stars are formed as a result of the gravitational collapse of massive stars during supernova explosions. The core of the star collapses under its own gravity, leading to the formation of a neutron-rich core.

Neutron stars typically have masses ranging from 1.4 to 3 solar masses. This is known as the Chandrasekhar limit, which represents the maximum mass a white dwarf can support before collapsing into a neutron star.

Neutron stars are primarily composed of neutrons, which are tightly packed together under immense gravitational pressure. The high density of neutrons leads to the unique properties and behavior of neutron stars.

Neutron stars have extremely compact sizes, with typical radii ranging from 10 to 20 kilometers. This is due to the immense gravitational forces that compress the matter within the star.

Neutron stars have extremely hot surfaces, with temperatures ranging from 100,000 to 1,000,000 Kelvin. This heat is generated by the decay of radioactive elements and the interactions of particles within the star.

Neutron stars possess extremely strong magnetic fields, ranging from 10^8 to 10^12 Gauss. These magnetic fields are generated by the rapid rotation of the star and the movement of charged particles within it.

Neutron stars have very rapid rotation periods, ranging from milliseconds to seconds. This rapid rotation is caused by the conservation of angular momentum during the collapse of the star.

Neutron stars can experience sudden and dramatic releases of energy known as neutron star flares. These flares are caused by the sudden reconfiguration of the star's magnetic field, releasing enormous amounts of energy.

A binary system consisting of a neutron star and a companion star is referred to as a neutron star binary. These systems are important for studying the properties of neutron stars and their interactions with other objects.

The first discovered neutron star was PSR B1919+21, also known as the Hulse-Taylor pulsar. It was discovered in 1974 by Russell Hulse and Joseph Taylor and became a significant milestone in the study of neutron stars.

The closest known neutron star to Earth is RX J185635-3754, located approximately 400 light-years away in the constellation Ophiuchus. It is a relatively young neutron star with a high magnetic field and a rapid rotation period.

The most massive neutron star known to date is PSR J0348+0432, located in the constellation Camelopardalis. It has a mass of approximately 2.01 solar masses, pushing the limits of the theoretical maximum mass for neutron stars.

The fastest-spinning neutron star known to date is PSR J1748-2446ad, located in the constellation Sagittarius. It has a rotation period of approximately 0.0014 seconds, or 1.4 milliseconds, making it the fastest-spinning known object in the universe.

The first discovered double neutron star system was PSR B1913+16, also known as the Hulse-Taylor binary. It consists of two neutron stars orbiting each other with a period of approximately 7.75 hours. This discovery provided strong evidence for the existence of gravitational waves.

The first discovered neutron star with a planetary system was PSR B1257+12, located in the constellation Virgo. It has a system of three planets, designated PSR B1257+12 A, B, and C, which were the first extrasolar planets ever discovered.