Globular Clusters Full of Millisecond Pulsars |
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Written by spacetravel.org
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Sunday, 22 May 2005 21:56 |
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Astronomers have been finding a large number of millisecond pulsars in globular clusters. Many millisecond pulsars are created in globular clusters. Over billions of years, relatively massive objects, such as neutron stars, sink toward the crowded cluster cores, where they are more likely to encounter normal binary stars. Gravity may cause one star to be flung out, with the neutron star taking its place in the binary system. A pulsar in a binary system with a star that becomes a red giant accretes matter from its expanding companion which speeds up its rotation to a speed of hundreds of revolutions per second, turning it into a millisecond pulsar. Pulsars normally have rotational periods of several seconds.
So far, astronomers have found 80 millisecond pulsars in globular clusters, 22 of them in 47 Tucanae. However, a globular cluster called Terzan 5, in the constellation Sagittarius, is expected to harbor as many as 200 millisecond pulsars, because it is more massive and has a denser core than 47 Tucanae. So far, 27 millisecond pulsars have been found in Terzan 5.
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