Stars are sometimes grouped by mass based upon their evolutionary behavior as they approach the end of their nuclear fusion lifetimes.
Very-low-mass stars with masses below 0.5 M☉ do not enter the asymptotic giant branch (AGB) but evolve directly into white dwarfs.
Low-mass stars with a mass below about 1.8–2.2 M☉ (depending on composition) do enter the AGB, where they develop a degenerate helium core.
[10] The first stars to form after the Big Bang may have been larger, up to 300 M☉ or more,[11] due to the complete absence of elements heavier than lithium in their composition.
[14][15] Smaller bodies are called brown dwarfs, which occupy a poorly defined grey area between stars and gas giants.
[16] The mass loss rate will increase when the Sun enters the red giant stage, climbing to (7–9)×10−14 M☉ y−1 when it reaches the tip of the red-giant branch.