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Pulsar cannibalizes companion.



Pulsar cannibalizes companion

The companion star of one of the fastest-spinning puslars yet foud is evaporating, and Columbia University Columbia University, mainly in New York City; founded 1754 as King's College by grant of King George II; first college in New York City, fifth oldest in the United States; one of the eight Ivy League institutions.  scientist Wlodzimierz Kluzniak and his colleagues have proposed a model that explains the behavior of this pair and the dearth of other such pairs in the universe.

Observations suggest the pulsar is eating away at its companion, tearing it apart with gamma-ray bombardment and then using its gases to feed the pulsar's appetite for more mass and faster spin. In the early stage of the pair's evolution, according to according to
prep.
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

3.
 Kluzniak and his associates, the pulsar -- a rapidly spinning, very dense neutron star neutron star, extremely small, extremely dense star, about double the sun's mass but only a few kilometers in radius, in the final stage of stellar evolution. Astronomers Baade and Zwicky predicted the existence of neutron stars in 1933.  -- is surrounded by an accretion disk accretion disk
n.
A disk of interstellar material surrounding a celestial object with an intense gravitational field, such as a black hole.



accretion disk 
 of matter that falls onto the surface of the pulsar and makes it spin faster. The accretion disk also radiates gamma rays Gamma rays

Electromagnetic radiation emitted from excited atomic nuclei as an integral part of the process whereby the nucleus rearranges itself into a state of lower excitation (that is, energy content).
 that "evaporate" matter from the companion's surface, Kluzniak and his co-workers propose in the July 21 NATURE. In the second stage of the pair's evolution, after the accretion disk is consumed by the neutron star, the pulsar itself radiates enough energy to tear matter from the companion star.

This matter is pulled onto the ever-more-rapidly spinning pulsar. After about 100 million years the companion should be completely gone, Kluzniak says.

Such parasitism parasitism: see parasite.
parasitism

Relationship between two species in which one benefits at the expense of the other. Ectoparasites live on the body surface of the host; endoparasites live in their hosts' organs, tissues, or cells and often rely
 was proposed in December, but this is the first good example of it, Kluzniak says. Kluzniak and two Dutch astronomers have suggested this mechanism may account for the scacity of certain binary-system pulsars with low-mass companion stars. When a companion star is small enough and close enough to a pulsar, Kluzniak and his colleagues suggest, the pulsar consumes it in a relatively short period.
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Publication:Science News
Date:Jul 30, 1988
Words:265
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