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red giant

noun Astronomy.
  1. a star in an intermediate stage of evolution, characterized by a large volume, low surface temperature, and reddish hue.
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Origin of red giant

First recorded in 1915–20
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for red giant

red giant

noun
  1. a giant star towards the end of its life, with a relatively low temperature of 2000–4000 K, that emits red light
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

red giant in Science

red giant

  1. A giant star that has a relatively low surface temperature, giving it a reddish or orange hue. Red giants are non-main-sequence stars positioned in the upper right of the Hertzsprung-Russell diagram. They are not massive stars but rather late, expanded stages of lower-mass main-sequence stars that have exhausted the hydrogen in their core and are fusing their remaining hydrogen into helium in a luminous outer shell. The Sun is expected to become a red giant in about 5 billion years, expanding to 70 times its current size and bringing its surface extremely close to Earth's present orbit. See more at star. See Note at dwarf star.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.