In the catalog of cosmic objects, neutron stars are certainly among the strangest elements. Products of the collapse of massive stars, the precise composition of these extremely dense objects is still unknown to astrophysicists. Certain particular forms of neutron stars, called pulsars, are of great interest to researchers in view of their stable radiation frequency over time. What do we know about these cosmic objects?
Ordinary stars retain their spherical shape because the increasing gravity of their gigantic mass tends toward internal gas collapse, but is balanced by the energy of nuclear fusion in their cores, which exerts outward pressure. At the end of their lives, stars that are between four and eight times the mass of the Sun burn up using their available fuel, and their internal fusion reactions cease.
The outer layers of stars quickly collapse inwards, bouncing off the thick core and then exploding again like a violent supernova. But the dense core continues to collapse, generating pressures so high that protons and electrons are squeezed together and form neutrons and light particles called neutrinos, which escape into the Universe.
The end result is a star whose mass is 90% neutrons, which can't be stuck together any more tightly, and so the neutron star can't decay any further. Astronomers first theorized the existence of these strange stellar entities in the 1930s, shortly after the discovery of the neutron. But it was not until 1967 that scientists had proof of the existence of neutron stars.
A graduate student named Jocelyn Bell, from the University of Cambridge in England, noticed strange pulses in her radio telescope, arriving so regularly that she at first thought they might be a signal from an extraterrestrial civilization, according to the American Physical Society . The patterns turned out not to be E.T. but rather radiation emitted by rapidly rotating neutron stars.
The supernova that gives birth to a neutron star transmits a large amount of energy to the compact object, causing it to rotate on its axis between 0.1 and 60 times per second, and up to 700 times per second. The formidable magnetic fields of these entities produce high-powered beams of radiation, which can sweep the Earth like beams from headlights, creating what is known as a pulsar.
The properties of neutron stars are quite exceptional; a single teaspoon of neutron star material would weigh a billion tons. If you were to somehow stand on their surface without dying, you would experience a force of gravity 2 billion times stronger than what you feel on Earth. The magnetic field of an ordinary neutron star could be billions of times stronger than that of Earth.
But some neutron stars have even more extreme magnetic fields, thousands of times higher than an average neutron star. This creates an object called a magnetar. Starquakes on the surface of a magnetar — the equivalent of movements in the Earth's crust that generate earthquakes — can release huge amounts of energy. In a tenth of a second, a magnetar could produce more energy than the sun has emitted in the past 100,000 years.
