When a massive star runs out of fuel, it will eventually undergo a catastrophic explosion known as a supernova. During this explosion, the outer layers of the star are blown away, leaving behind a collapsed core. If the core is between 1.4 and 3 times the mass of the sun, it will collapse into a neutron star. Neutron stars are incredibly dense objects, with a mass of about 1.4 times that of the sun, but a diameter of only about 10 kilometers. This means that they are incredibly dense, with a density of around 10^14 grams per cubic centimeter.
Pulsars are a type of neutron star that emits beams of radiation that sweep across the sky as the star rotates. These beams can be detected as pulses of radiation, which is why they are called pulsars. Pulsars are incredibly accurate timekeepers, with some pulsars having rotation periods that are accurate to within a few nanoseconds.
The study of neutron stars and pulsars has led to many interesting discoveries in astrophysics. For example, the observation of pulsars in binary star systems has provided evidence for the existence of gravitational waves, which are ripples in space-time that were predicted by Einstein's theory of general relativity. Neutron stars are also thought to be responsible for some of the most energetic phenomena in the universe, such as gamma-ray bursts.
In conclusion, neutron stars and pulsars are incredibly dense objects that form from the remnants of supernovae. These objects are fascinating to study and have led to many interesting discoveries in astrophysics. As we continue to study these objects, we will undoubtedly uncover more secrets of the universe and its creation.