neutron star

American  

noun

1. an extremely dense, compact star composed primarily of neutrons, especially the collapsed core of a supernova.

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neutron star British  

noun

1. a star that has collapsed under its own gravity to a diameter of about 10 to 15 km. It is composed mostly of neutrons, has a mass of between 1.4 and about 3 times that of the sun, and a density in excess of 10 ¹⁷ kilograms per cubic metre

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neutron star Scientific  

1. A celestial object consisting of an extremely dense mass of neutrons, formed at the core of a supernova, where electrons and nuclei are compressed together so intensely by the force of gravity that protons and electrons merge together into neutrons. Though their mass is close to that of the Sun, the density of neutron stars is much higher—about 3 × 10 ¹¹ kilograms per cubic centimeter (by comparison, the density of steel is 7.7 grams per cubic centimeter). Neutron stars are typically about 10 km across, and rotate very rapidly. Due to the spinning of electrically charged protons and electrons at their surfaces, their rotation gives rise to strong magnetic fields. The existence of neutron stars was predicted in the 1930s but was not confirmed until the discovery of the first pulsar in 1967.

2. See more at pulsar

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neutron star Cultural  

1. A star about the size of the Earth, made almost entirely of neutrons. It is the end product of the evolution of some stars larger than the sun.

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Etymology

Origin of neutron star

First recorded in 1930–35

Example Sentences

See Examples For:

neutron star

Astronomers have, for the first time, observed the birth of a magnetar, an extremely magnetic, rapidly spinning type of neutron star.

From Science Daily ● Jul. 6, 2026

Because this disk was likely tilted relative to the magnetar's spin, Einstein's theory predicts that the rapidly spinning neutron star would drag the surrounding fabric of space-time with it, producing a phenomenon called Lense-Thirring precession.

From Science Daily ● Jul. 6, 2026

"This work has the potential to explain the magnetic dynamics relevant in, for example, neutron star mergers and black hole formation, with direct applications to multimessenger astronomy," Tripathi says.

From Science Daily ● May 26, 2026

Researchers have also only been able to measure neutron star masses in binary systems where two objects orbit each other.

From Science Daily ● May 15, 2026

As the core of a massive red giant collapses to form such a neutron star, it spins faster.

From "Cosmos" by Carl Sagan