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M star

American

noun

Astronomy.

a relatively cool, red star, as Antares or Betelgeuse, having a surface temperature of less than 3600 K and an absorption spectrum dominated by molecular bands, especially titanium oxide.

Example Sentences

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Estimating the luminosity class of an M star is much more important than measuring it for an O star if you are determining the distance to that star.

From Textbooks • Oct. 13, 2016

How many times cooler than our Sun is the coolest type M star?

From Textbooks • Oct. 13, 2016

Our Sun, a type G star, has a surface temperature of 5800 K. We know, therefore, that it is cooler than a type O star and hotter than a type M star.

From Textbooks • Oct. 13, 2016

The nearest star to the Sun, Proxima Centauri, is an M star that has a planet with a mass of at least 1.3 Earth masses, taking about 11 days to orbit.

From Textbooks • Oct. 13, 2016

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