Among the universe's most extraordinary objects, neutron stars stand out for their bizarre nature. Formed from the collapse of massive stars, their precise internal composition remains one of astrophysics' enduring mysteries. Pulsars—a special class of neutron stars—fascinate scientists with their precise, stable radiation pulses. What do experts know about these cosmic powerhouses?
Ordinary stars maintain their spherical shape through a delicate balance: gravity pulls inward from their immense mass, countered by outward pressure from nuclear fusion in their cores. For stars 4 to 8 times the Sun's mass, fuel eventually runs out at the end of their lives, halting fusion.
The star's outer layers collapse inward, rebound off the dense core, and erupt in a spectacular supernova. Yet the core keeps compressing under extreme pressure, forcing protons and electrons to merge into neutrons and neutrinos, which stream into space.
The result is a star roughly 90% neutrons, so densely packed it resists further collapse. Theorized by astronomers in the 1930s soon after neutrons were discovered, neutron stars weren't confirmed until 1967.
Jocelyn Bell, a graduate student at Cambridge University, detected oddly regular radio pulses through her telescope—initially dubbed 'LGM-1' for possible alien origins, per the American Physical Society. They proved to be emissions from swiftly spinning neutron stars.
The birth supernova imparts tremendous spin to the neutron star, from 0.1 to 60 rotations per second—and up to 700 in some cases. Their powerful magnetic fields generate intense radiation beams that, when sweeping across Earth like lighthouse signals, reveal them as pulsars.
Neutron stars boast staggering traits: a teaspoon of their matter weighs a billion tons. Standing on one (hypothetically) would crush you under gravity 2 billion times Earth's. Their magnetic fields dwarf Earth's by billions of times.
Some neutron stars, called magnetars, amplify this with fields thousands of times stronger. 'Starquakes' on a magnetar's surface—akin to earthquakes—can unleash more energy in a tenth of a second than the Sun produces in 100,000 years.
