"A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich."
The remnants of a supernova explosion, which are incredibly dense and small, but still follow the laws of physics.
General Relativity: The theoretical framework that describes the behavior of gravity and the curvature of spacetime.
Neutron Stars: The most dense objects in the universe, made up of compressed neutrons and formed from the remnants of supernova explosions.
Pulsars: Rapidly rotating neutron stars that emit beams of electromagnetic radiation, which are detected as pulses of radio waves.
Gravitational Waves: Waves of distorted spacetime that are produced by accelerating massive objects, such as neutron stars, and can be detected with specialized instruments like LIGO.
Black Holes: Extremely dense objects formed from the remains of collapsed stars, which have such strong gravitational fields that not even light can escape them.
Accretion Disks: The disk-shaped clouds of gas and dust that form around black holes and neutron stars as they capture material from nearby stars.
Gamma-Ray Bursts: Brief bursts of gamma-ray radiation thought to be caused by the collision of neutron stars, which are some of the most energetic events in the universe.
Magnetars: Neutron stars with strong magnetic fields that can produce intense bursts of radiation and other powerful eruptions.
Supernovae: The explosive deaths of massive stars, which produce and distribute heavy elements throughout the universe and can also leave behind neutron stars.
X-ray Binaries: Binary star systems in which one star is a neutron star or black hole and the other is a main-sequence star, which can lead to the emission of X-rays from the accretion disk around the compact object.
Equation of State: A mathematical description of the relationship between the pressure and density of matter, which is used to understand the behavior of matter in neutron stars and other extreme environments.
Neutron Star Mergers: The collision and merging of two neutron stars, which can produce a variety of phenomena including gravitational waves, gamma-ray bursts, and the production of heavy elements like gold and platinum.
Neutrinos: Subatomic particles that are produced in large numbers during supernovae and other high-energy astrophysical events, and can provide important information about the nature of these phenomena.
Neutron Star Crusts: The solid outer layer of a neutron star, which is thought to be made up of a lattice of atomic nuclei and free-roaming electrons.
Neutron Star Interiors: The dense, superfluid core of a neutron star, which is thought to contain exotic forms of matter like hyperons and pions.
Standard Neutron Stars: These are the most common neutron stars that have a mass 1.4 times that of the Sun and a radius of about 10 km. They are formed through the gravitational collapse of a massive star, and they are incredibly dense, with a core made up of neutrons.
Magnetars: Magnetars are neutron stars with incredibly strong magnetic fields, about 1000 times stronger than the normal neutron star. They are considered to be the most magnetic objects in the known universe. Magnetars are known to produce some of the most powerful electromagnetic emissions in the cosmos, including X-rays and gamma rays.
Pulsars: Pulsars are a type of neutron star that emits beams of radiation that are detected as regular pulses. These are believed to result from the neutron star's incredibly strong magnetic fields, which cause the emission of radiation that is focused into a narrow beam by the rotation of the star.
Quark Stars: Quark stars are a hypothetical type of neutron star that are composed of quark matter. They are believed to be even more dense than standard neutron stars, with a hypothetical mass-to-radius ratio that is even higher. Nonetheless, quark stars are still considered hypothetical objects and there is still ongoing research to determine if they exist.
"Except for black holes, neutron stars are the smallest and densest known class of stellar objects."
"They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei."
"Neutron stars are partially supported against further collapse by neutron degeneracy pressure, just as white dwarfs are supported against collapse by electron degeneracy pressure."
"If the remnant star has a mass exceeding the Tolman–Oppenheimer–Volkoff limit of approximately 2.1 M☉, the combination of degeneracy pressure and nuclear forces is insufficient to support the neutron star, causing it to collapse and form a black hole."
"Neutron stars that can be observed are extremely hot and typically have a surface temperature of around 600,000 K."
"Neutron star material is remarkably dense: a normal-sized matchbox containing neutron-star material would have a weight of approximately 3 billion tonnes, the same weight as a 0.5-cubic-kilometer chunk of the Earth."
"Their magnetic fields are between 108 and 1015 times stronger than Earth's magnetic field."
"As a star's core collapses, its rotation rate increases due to conservation of angular momentum, and newly formed neutron stars rotate at up to several hundred times per second."
"The discovery of pulsars by Jocelyn Bell Burnell and Antony Hewish in 1967 was the first observational suggestion that neutron stars exist."
"The fastest-spinning neutron star known is PSR J1748-2446ad, rotating at a rate of 716 times per second or 43,000 revolutions per minute."
"There are thought to be around one billion neutron stars in the Milky Way."
"Neutron stars in binary systems can undergo accretion, in which case they emit large amounts of X-rays."
"Binary systems such as these continue to evolve, with many companions eventually becoming compact objects such as white dwarfs or neutron stars themselves, though other possibilities include a complete destruction of the companion through ablation or collision."
"The collision of binary neutron stars may be the source of short-duration gamma-ray bursts."
"In 2017, a direct detection of the gravitational waves from such an event was observed, along with indirect observation of gravitational waves from the Hulse-Taylor pulsar."
"Once formed, neutron stars no longer actively generate heat and cool over time."
"Most of the basic models for these objects imply that they are composed almost entirely of neutrons."
"Most neutron stars that have been detected occur only in certain situations in which they do radiate, such as if they are a pulsar or a part of a binary system. Slow-rotating and non-accreting neutron stars are difficult to detect, due to the absence of electromagnetic radiation."
"During this process, matter is deposited on the surface of the stars, forming 'hotspots' that can be sporadically identified X-ray pulsar systems."