Pulsaren

Pulsaren, commonly known in English as pulsars, are highly magnetized, rotating neutron stars that emit beams of electromagnetic radiation from their magnetic poles. As the star spins, these beams sweep through space; when a beam crosses Earth, we observe a pulse, giving the object a clocklike regularity.

Pulsaren were first identified in 1967 by Jocelyn Bell Burnell and Antony Hewish. The steady, periodic radio signals were initially nicknamed LGM for "little green men" but were soon understood as rotating neutron stars produced by supernova explosions. The first discovered pulsar, PSR B1919+21, has a period of about 1.3 seconds.

Most pulsaren rotate from milliseconds to a few seconds per turn and possess magnetic fields much stronger than laboratory fields, roughly 10^8–10^12 gauss (10^4–10^8 tesla). Their emission is believed to arise from charged particles accelerated along open magnetic field lines near the magnetic poles, producing radiation predominantly in the radio band, with many also emitting in X-ray and gamma-ray wavelengths.

Pulsaren are broadly classified as rotation-powered pulsars. A subset, millisecond pulsars, have been spun up by accretion in binary systems and can rotate with periods of a few milliseconds. A related group, magnetars, are neutron stars with especially strong magnetic fields (up to 10^14–10^15 gauss) and are notable for X-ray and gamma-ray outbursts.

Scientific value includes precise timing for tests of general relativity in binary systems, constraints on the equation of state of dense matter, and the use of pulsaren as galactic clocks and detectors for nanohertz gravitational waves via timing arrays. Notable examples include the Crab Pulsar (PSR B0531+21) and the Vela Pulsar (PSR B0833−45).