Stars - Research Article from Macmillan Science Library: Space Sciences

This encyclopedia article consists of approximately 4 pages of information about Stars.
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Main Sequence Stars

When the star has accumulated enough material so that the temperature and pressure are high enough, nuclear fusion reactions, which convert hydrogen into helium, begin deep within the core of the star. The energy from the reactions makes its way to the surface of the star in about a million years, causing the star to shine. The pressure from these nuclear reactions at the star's core balances the pull of gravity, and the star is now called a main sequence star.

This name is derived from the relationship between a star's intrinsic brightness and its temperature, which was discovered independently by Danish astronomer Ejnar Hertzsprung (in 1911) and American astronomer Henry Norris Russell (in 1913). This relationship is displayed in a Hertzsprung-Russell diagram. A star's color depends on its surface temperature; red stars are the coolest and blue stars are the hottest. The temperature, brightness, and longevity of...

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This section contains 1,093 words
(approx. 4 pages at 300 words per page)
Buy the Stars Encyclopedia Article
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Macmillan Science Library: Space Sciences
Stars from Macmillan Science Library: Space Sciences. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.
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