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单词 star cluster
释义
star cluster

Physics
  • A group of stars that are sufficiently close to each other for them to be physically associated. Stars belonging to the cluster are formed together from the same cloud of interstellar gas and have approximately the same age and initial chemical composition. Because of this, and since the stars in a given cluster are at roughly the same distance from earth, observations of star clusters are of great importance in studies of stellar evolution.

    There are two types of star cluster. Open (or galactic) clusters are fairly loose systems of between a few hundred and a few thousand members. The stars in open clusters are quite young by astronomical standards (some as young as a few million years) and have relatively high abundances of heavy elements. Globular clusters are approximately spherical collections of between ten thousand and a million stars. These are very old (of order 1010 years) and have low heavy-element abundances.


Astronomy
  • A collection of stars formed together from the same gas cloud and bound together by mutual gravitational attraction. There are two main types of star cluster. Globular clusters contain from tens of thousands to millions of old stars packed into a near-spherical ball, and are found in the haloes of galaxies. Open clusters are much more sparse and irregular in shape, consisting of no more than a few hundred relatively young stars in the spiral arms of galaxies. A group looser than an open cluster is known as a stellar association.


Space Exploration
  • A group of related stars, usually held together by gravity. Members of a star cluster are thought to form together from one large cloud of gas in space.

    Open clusters such as the Pleiades contain from a dozen to many hundreds of young stars, loosely scattered over several light years. Globular clusters are larger and much more densely packed, containing perhaps 10 000–1 000 000 stars.


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