A low-mass star that's very cool, and emits a red light.
A red dwarf is a kind of star whose mass is between 0.08 and 0.4 times that of the Sun. The energy released by nuclear fusion in a red dwarf is carried to the star's surface by the circular motion of the hot gasses inside it.
Red dwarfs are much fainter, cooler and smaller than the Sun. They are the most common type of star in the galaxy accounting for 70 percent of all stars.