Neutron stars are small (about 20km across), rotate rapidly and are incredibly dense. They are mostly made of neutrons that formed as electrons combined with protons in the atomic nuclei of the dying stars' collapsing cores. Their powerful magnetic fields lead to radio pulses that can be detected on the Earth each time they rotate. These objects are known as pulsars when the pulses can be detected on the Earth.
Image: The Vela pulsar jet (credit: NASA/CXC/PSU/G.Pavlov et al.)
Pulsars send signals across the Universe.
Frank Drake describes the rhythms found in pulsar signals.
In the late 1960s, Frank Drake describes pulsars and the patterns found in their signals.
Jocelyn Bell Burnell explains how pulsars tested Einstein's theory.
Jocelyn Bell Burnell explains how her pulsar discovery helped test general relativity. She also discusses the difference between a search for truth and a search for understanding.
Jocelyn Bell Burnell's discovery paves the way for black holes' acceptance.
Jocelyn Bell Burnell's discovery of pulsars paved the way for the acceptance of black holes as a serious idea.
Jocelyn Bell Burnell explains what they are and how they got their name.
Professor Dame Jocelyn Bell Burnell explains what pulsars are and how they got their name.
Patrick Moore listens to pulsars at Jodrell Bank.
Sir Patrick Moore listens to pulsars at Jodrell Bank Observatory.
A pulsar (portmanteau of pulsating star) is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. This radiation can only be observed when the beam of emission is pointing toward the Earth, much the way a lighthouse can only be seen when the light is pointed in the direction of an observer, and is responsible for the pulsed appearance of emission. Neutron stars are very dense, and have short, regular rotational periods. This produces a very precise interval between pulses that range from roughly milliseconds to seconds for an individual pulsar.
The precise periods of pulsars make them useful tools. Observations of a pulsar in a binary neutron star system were used to indirectly confirm the existence of gravitational radiation. The first extrasolar planets were discovered around a pulsar, PSR B1257+12. Certain types of pulsars rival atomic clocks in their accuracy in keeping time.
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