Pulsernas

Pulsernas, commonly referred to as pulsars in English, are highly magnetized, rotating neutron stars that emit beams of electromagnetic radiation from their magnetic poles. The beams sweep around as the star spins; if the beam crosses Earth, we observe a periodic pulse. Pulsars were first discovered in 1967 by Jocelyn Bell Burnell and Antony Hewish while studying radio sources at Cambridge. The signals were remarkably regular, leading to the recognition of a new class of cosmic objects. Pulsar periods span from about 1.4 milliseconds to several seconds, and their radiation can be observed in radio, as well as X-ray and gamma-ray bands.

Pulsars are the remnants of massive stars that exploded as supernovae. They host extremely strong magnetic fields, typically 10^8 to 10^15 gauss, and contain about 1.2–2 solar masses within a radius of roughly 10 kilometers. They are observed in several varieties: ordinary radio pulsars, millisecond pulsars that have been spun up through accretion in binary systems, and magnetars, which have the strongest magnetic fields and often emit high-energy radiation.

Pulsars serve as precise cosmic clocks. Their regular pulses enable tests of general relativity in binary systems, studies of the interstellar medium through dispersion, and, through pulsar timing arrays, the search for low-frequency gravitational waves. They are predominantly found in the Milky Way, including in globular clusters, with a smaller number identified in nearby galaxies.

The term pulsar is derived from pulsating radio star. See also neutron star, magnetar, pulsar timing, and gravitational waves.