Glossary of Astronomical Terms/red dwarf

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A "red dwarf" is a main sequence star whose mass is less than about 0.4 solar masses. Red dwarfs are characterized by having highly convective interiors which results in a uniform mixing of nuclear fuels throughout the star. Thus, unlike larger main sequence stars like the Sun, red dwarfs do not depend on just the hydrogen at their cores for fuel, making them very long-lived (100 billion years or so). This convection also means red dwarfs do not accumulate helium (the by-product of hydrogen fusion) at their cores. A red dwarf, therefore, will never become a red giant like a more massive main sequence star since a red giant expands to its enormous size because of hydrogen fusing in a shell around a helium core. Red dwarfs should eventually become white dwarfs as their nuclear processes wind down.