Red Dwarf or M Dwarf or M-Type Stars

Red dwarf star is the smallest and coolest kind of star on the main sequence. It is the most numerous type of star in the universe and the smallest type of hydrogen-burning star. Proxima Centauri is the nearest star to the Sun, is a red dwarf.

Red dwarf stars have masses from about 0.08 to 0.6 times that of the sun (Objects smaller than red dwarf stars are called brown dwarfs and do not shine through the thermonuclear fusion of hydrogen). Lighter stars are much more plentiful than heavier stars, and red dwarfs are thus the most numerous type of star. In the milkyway galaxy, about three-fourths of the stars are red dwarfs. The proportion is even higher in elliptical galaxies.

Red dwarfs are the coolest main-sequence stars, with a spectral type of M and a surface temperature of about 2,000–3,500 K. . Red dwarfs are also the dimmest stars, with luminosities between about 0.0001 and 0.1 times that of the Sun.Red dwarfs will not pass through a red giant phase in their evolution. Because convection occurs through the entire star, hydrogen is constantly recirculated from the outer regions to the core. Red dwarfs, because of convection, are completely efficient and will burn their entire supply of hydrogen. They will then become hotter and smaller, turning into blue dwarfs and finally ending their lives as white dwarfs.
Low-mass red dwarfs develop very slowly, maintaining a constant luminosity and spectral type for trillions of years, until their fuel is depleted. Because of the comparatively short age of the universe, no red dwarfs exist at advanced stages of evolution.

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