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What Is a Pulsar?

AstronomyAstrophysics

Quick Answer

A pulsar is a rapidly spinning neutron star that emits beams of electromagnetic radiation from its magnetic poles; as the star rotates, these beams sweep across space like a lighthouse.

The Full Story

When a massive star explodes as a supernova, the collapsed core can form a neutron star — an object roughly 20 km across but with 1.4-2 times the Sun mass. Conservation of angular momentum during collapse spins the neutron star up to extraordinary rotation rates. Strong magnetic fields (up to 10^15 gauss in magnetars) channel radiation into narrow beams from the magnetic poles, which may not align with the rotation axis. When such a beam sweeps past Earth, we detect regular pulses — hence "pulsar" (pulsating star). Jocelyn Bell Burnell and Antony Hewish discovered the first pulsar in 1967; its signal was so regular (1.337 seconds) they half-jokingly labelled it LGM-1 ("Little Green Men"). Millisecond pulsars spin hundreds of times per second and are among the most precise clocks in the universe, rivalling atomic clocks.

Key Facts

1.The fastest known pulsar, PSR J1748-2446ad, spins 716 times per second — its equator moves at about 24% of the speed of light.
2.Over 3,300 pulsars have been catalogued as of 2024, mostly detected by radio telescopes like Arecibo and Parkes.
3.Pulsar timing arrays may soon detect gravitational waves from supermassive black hole mergers by measuring tiny irregularities in pulsar signals.

YouTube Angle

Suggested video title for this topic:

"Pulsars — The Cosmic Lighthouses of Dead Stars"