Why Do Neutron Stars Spin?

Neutron stars are one of the most fascinating objects in the universe. They are the collapsed remnants of massive stars that have undergone a supernova explosion. These stars are incredibly dense and have an immense gravitational pull. One of the most intriguing features of neutron stars is their rapid spin. Neutron stars can rotate at a staggering rate of hundreds of times per second, but why do they spin so fast? In this write-up, we will explore the reasons behind the high rotation of neutron stars.

The Basics of Neutron Stars

Neutron stars are one of the universe’s most mysterious and fascinating objects. They are incredibly dense, with a mass greater than that of the sun and a radius of only about 10 kilometers. Neutron stars are created when a massive star runs out of fuel and collapses under its own gravity, forming a core made up of tightly packed neutrons. These stars are incredibly hot, with temperatures reaching millions of degrees.

What Makes Neutron Stars Spin?

One of the most intriguing things about neutron stars is that they spin incredibly fast. Some neutron stars can rotate hundreds of times per second, making them some of the fastest spinning objects in the universe. But what causes neutron stars to spin so quickly?

The Conservation of Angular Momentum

The answer lies in the conservation of angular momentum. Angular momentum is a measure of an object’s rotational motion, and it is conserved in the absence of external torques. When a massive star collapses into a neutron star, its angular momentum is conserved, meaning that the neutron star inherits the star’s rotation.

How Neutron Stars Can Speed Up

But neutron stars can also speed up over time. This is because they emit a type of radiation called electromagnetic radiation, which carries away energy and angular momentum. As the neutron star emits more and more radiation, it spins faster and faster. This process is known as “spin-up.”


Neutron stars that emit beams of electromagnetic radiation are called pulsars. Pulsars were first discovered in 1967 by Jocelyn Bell Burnell and Antony Hewish. They noticed a series of regular radio pulses coming from a specific point in the sky and eventually realized that they were coming from a rapidly spinning neutron star.


Another type of neutron star is the magnetar. These stars have incredibly strong magnetic fields, trillions of times stronger than the Earth’s magnetic field. Magnetars can emit powerful bursts of X-rays and gamma rays, and they can also experience massive starquakes that cause the star’s magnetic field to twist and distort, releasing huge amounts of energy.

FAQs – Why do Neutron Stars Spin?

What is a neutron star?

A neutron star is a type of remnant that is left after a very massive star has exploded in a supernova. The neutron star is extremely dense, with a mass of around 1.4 times that of the sun compressed into a sphere with a diameter of only about 20 km. The neutron star is made almost entirely of neutrons, since protons and electrons have merged to form neutrons. Neutron stars are also incredibly hot and magnetized, making them sources of powerful radiation.

Why do neutron stars spin?

When a massive star explodes in a supernova, it can leave behind a compact object that spins very rapidly. This is because the original star’s rotation is conserved – much like an ice skater pulling in their arms and spinning more quickly. A neutron star is formed by the collapse of the star’s core, which causes it to spin more rapidly. In addition, some neutron stars are found to be in binary systems with other objects, such as another neutron star or a white dwarf. These stars can pass matter between them, which can cause changes in the neutron star’s spin.

How fast do neutron stars spin?

Neutron stars can spin very rapidly, with some neutron stars rotating hundreds of times per second. In fact, neutron stars are the fastest spinning objects known in the universe. The rate at which a neutron star spins can be measured by observing the pulsations of radiation emitted from its surface. These pulsars emit beams of radiation that are detectable from Earth, and the consistency of their pulses can be used to estimate their rotation period.

What happens when a neutron star slows down?

Neutron stars can slow down over time due to various factors, including the emission of radiation and the transfer of angular momentum to the surrounding material. However, the amount of radiation emitted by a neutron star is dependent on its spin rate, so as it slows down, it emits less radiation and becomes less visible. Eventually, if the neutron star slows down enough, it may cease to emit pulsations and become what is known as a ‘dead’ neutron star.

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