red giant
Definition
Noun: A red giant is a large, old star in a late stage of stellar evolution. It is characterized by its immense size, relatively low surface temperature (which gives it a red or orange appearance), and high luminosity. A red giant's diameter is typically much larger than that of the Sun.
Usage
The term red giant is used specifically in astronomy to classify and describe a particular phase in a star's life cycle. * Our Sun will eventually become a red giant, expanding to engulf the inner planets. * Betelgeuse in the constellation Orion is a well-known red giant. * Astronomers study the chemical composition of red giant stars.
Advanced Usage
- Red giant branch (RGB): Refers to a specific stage of evolution for low- to intermediate-mass stars after they exhaust hydrogen in their cores.
- The star is currently ascending the red giant branch.
- Red giant phase: Describes the period of time a star spends as a red giant.
- The red giant phase lasts for a relatively short time compared to the star's main-sequence life.
Variants and Related Words
- Red supergiant (noun): An even more massive and luminous evolved star, representing a later stage for high-mass stars.
- Antares is a red supergiant, far larger than a typical red giant.
- Asymptotic Giant Branch (AGB) star (noun): A later, thermally pulsing phase of evolution for a red giant.
Synonyms
- Giant star (noun): A broader category that includes red giants as well as other large, luminous stars like blue giants.
- Evolved star (noun): A general term for a star that has moved past the main-sequence stage of its life.
Antonyms / Contrasting Terms
- Main-sequence star (noun): A star, like our current Sun, that is in the stable, hydrogen-burning phase of its life, before it becomes a red giant.
- White dwarf (noun): The final, hot, dense remnant left behind after a red giant sheds its outer layers.
- Dwarf star (noun): A star of relatively small size and luminosity, such as a red dwarf or the Sun (a yellow dwarf).
Noun
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a large, old, luminous star; has a relatively low surface temperature and a diameter large relative to the sun
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