Evolution of a very-low-mass star. Illustration of the main stages in the life of a very-low-mass star such as a low-mass red dwarf, less than a quarter of the mass of our Sun. A star is born from the gravitational contraction of clouds of gas, initially forming a protostar. Due to the contraction, the temperature of the gas increases until it triggers the nuclear fusion of hydrogen atoms, and the star enters its main sequence phase. Low-mass red dwarfs burn slowly and have very long lifespans, possibly trillions of years. It is thought that eventually they evolve into white dwarfs, dense stellar remnants which finally cool to form black dwarfs.