中子星，是恒星演化到末期，经由引力坍缩发生超新星爆炸之后，可能成为的少数终点之一。恒星在核心的氢、氦、碳等元素于核聚变反应中耗尽，当它们最终转变成铁元素时便无法从核聚变中获得能量。失去热辐射压力支撑的外围物质受重力牵引会急速向核心坠落，有可能导致外壳的动能转化为热能向外爆发产生超新星爆炸，或者根据恒星质量的不同，恒星的内部区域被压缩成白矮星、中子星或黑洞。白矮星被压缩成中子星的过程中恒星遭受剧烈的压缩使其组成物质中的电子并入质子转化成中子，直径大约只有十余公里，但上面一立方厘米的物质便可重达十亿吨，且旋转速度极快。由于其磁轴和自转轴并不重合，磁场旋转时所产生的无线电波等各种辐射可能会以一明一灭的方式传到地球，有如人眨眼，此时称作脉冲星。

A neutron star is a type of compact star. Neutron stars are the smallest and densest stars known to exist in the Universe. With a radius of only about 11–11.5 km (7 miles), they can, however, have a mass of about twice that of the Sun. They can result from the gravitational collapse of a massive star that produces a supernova. Neutron stars are composed almost entirely of neutrons, which are subatomic particles with no net electrical charge and with slightly larger mass than protons. They are supported against further collapse by the repulsive strong nuclear force as well as quantum degeneracy pressure due to the phenomenon described by the Pauli exclusion principle. Neutron stars are very hot and typically have a surface temperature around 7005600000000000000♠6×10 K. They are so dense that a normal-sized matchbox containing neutron-star material would have a mass of approximately 5 trillion tons, or 1000 km of Earth rock. They have strong magnetic fields, between 10 and 10 times as strong as that of Earth. The gravitational field at the star's surface is about 2×10 times stronger than on Earth.