red dwarf

American  

noun

Astronomy.

1. any of the faint reddish stars having diameters about half that of the sun and low surface temperatures, about 2000–3000 K; a main sequence star of spectral type M.

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red dwarf British  

noun

1. one of a class of small cool main-sequence stars

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red dwarf Scientific  

1. A small, dim star with relatively cool surface temperatures, positioned to the lower right on the main sequence in the Hertzsprung-Russell diagram. Red dwarfs, at about 0.1 to 0.5 solar mass, consume their nuclear fuel very slowly and live for about 100 billion years. Although they are difficult to see, they are so long-lived that they are likely the most abundant type of star; of the 30 nearest stars to Earth, 21 are red dwarfs, including the closest star, Proxima Centauri.

2. See Note at dwarf star

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Etymology

Origin of red dwarf

First recorded in 1915–20

Example Sentences

There’s a sci-fi podcast called “Wolf 359,” about a crew of a space station circling a red dwarf star.

From Los Angeles Times • Apr. 16, 2026

Barnard’s star, named after the astronomer, is a red dwarf floating in our Solar System’s neighbourhood.

From Space Scoop • Apr. 23, 2025

With another radio array, MeerKAT in South Africa, they narrowed its location and found it was close to a known red dwarf.

From Science Magazine • Dec. 3, 2024

The host star, called Gliese 12, is a cool red dwarf located almost 40 light-years away in the constellation Pisces.

From Science Daily • May 23, 2024

And high above them all, looking down, is the red dwarf, just like Dad said.

From "The Last Cuentista" by Donna Barba Higuera