Neutron Stars & Pulsars
What Are Neutron Stars?
Neutron stars are the collapsed cores of massive stars that exploded as supernovae. When a star between 10 and 29 times the mass of the Sun dies, its core collapses under gravity, crushing atoms together until protons and electrons merge to form neutrons. The result is an object with the mass of a star but only about 20 kilometers in diameter.
A teaspoon of neutron star material would weigh about a billion tons on Earth. These objects have incredibly strong magnetic fields—trillions of times stronger than Earth's—and rotate at speeds up to hundreds of times per second. Neutron stars represent matter in its most extreme state, with densities exceeding that of atomic nuclei.
Pulsars: Cosmic Lighthouses
Pulsars are rapidly rotating neutron stars that emit beams of radiation from their magnetic poles. As the star rotates, these beams sweep across space like a lighthouse, creating regular pulses of light, radio waves, X-rays, or gamma rays that can be detected on Earth.
Discovered in 1967, pulsars are among the most precise clocks in the universe, with some maintaining accuracy better than atomic clocks. The first exoplanets were discovered orbiting a pulsar in 1992. Pulsars have been used to test Einstein's theory of general relativity and are being considered as navigation beacons for future interstellar spacecraft.
Magnetars & Extreme Physics
Magnetars are a special type of neutron star with magnetic fields a thousand times stronger than ordinary neutron stars. These extreme magnetic fields can cause "starquakes" that release enormous amounts of energy in gamma-ray bursts. A magnetar's magnetic field is so strong it would erase the data on every credit card on Earth from halfway to the Moon.
Neutron star mergers create some of the most energetic events in the universe, producing gravitational waves, gamma-ray bursts, and heavy elements like gold and platinum. The 2017 detection of gravitational waves from two merging neutron stars marked the beginning of "multi-messenger astronomy," combining gravitational wave and electromagnetic observations to study cosmic events.
