pulsar

[puhl-sahr]
noun
Astronomy. one of several hundred known celestial objects, generally believed to be rapidly rotating neutron stars, that emit pulses of radiation, especially radio waves, with a high degree of regularity.

Origin:
1965–70; puls(ating st)ar, on the model of quasar

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World English Dictionary
pulsar (ˈpʌlˌsɑː)
 
n
any of a number of very small extremely dense objects first observed in 1967, which rotate very rapidly and emit very regular pulses of polarized radiation, esp radio waves. They are thought to be neutron stars formed following supernova explosions
 
[C20: from puls(ating st)ar, on the model of quasar]

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Etymonline
Word Origin & History

pulsar
1968, from pulse, the form on analogy of quasar. When discovered in 1967, they were thought perhaps to be signals from alien civilizations and astronomers informally dubbed them LGM for "Little Green Men."
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
pulsar   (pŭl'sär')  Pronunciation Key 
A rapidly spinning neutron star that emits radiation, usually radio waves, in narrow beams focused by the star's powerful magnetic field and streaming outward from its magnetic poles. Because the pulsar's magnetic poles do not align with the poles of its rotational axis, the beams of radiation sweep around like the beacon of a lighthouse and are thus observed on Earth as short, regular pulses, with periods anywhere between 1 millisecond and 4 seconds.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary
pulsar [(pul-sahr)]

A rapidly rotating neutron star. The radiation from such a star appears to come in a series of regular pulses (one per revolution), which explains the name.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Example sentences
It could be a rapidly rotating, extremely dense neutron star called a pulsar.
These leave behind a dense object known as a pulsar, which forms from the core
  of the exploding star.
Their magnetic poles emit electromagnetic radio waves, so each time a pulsar
  spins, it sends out a radio blip.
Astronomers have tracked the movement of a pulsar, making the first direct
  measurement of its impressive speed.
Images for pulsar
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