# Evolution of red dwarf stars

While low mass stars (initial mass approximately $$0.1 M_\odot$$ to $$0.8 M_\odot$$) are quite numerous, their evolution seems to draw relatively little attention. The lower central density and temperature, compared to massive stars, result in a very long lifetime. The star being fully convective, a larger fraction of the hydrogen is available to fusion in the center. This further extends the star's lifetime to more than 10 Gy.

Apart from this, what are the principle differences in evolution of a solitary low mass star compared to the Sun's? Will a red dwarf ever burn helium, will it have a central helium flash, will it become a red giant and then a white dwarf?

Red dwarfs with a present age of 10 Gy were formed when the Galactic metallicity still was low. How does the original metallicity of a red dwarf influence it's evolution?

At solar metallicity, only stars with masses below 0.35$$M_{\odot}$$ are fully convective. Stars with $$0.35 will have radiative cores on the main sequence.
Stars below $$0.16 M_{\odot}$$ don't ascend the giant branch. Stars with $$0.16 < M/M_{\odot} <0.25$$ begin the ascent of the giant branch but don;t get as far as being very red or giant. Stars from $$0.25 become red giants, but never make it to helium burning before complete dgeneracy sets in. Above this, stars behave "normally" and become red giants, go through He burning and end up as C/O white dwarfs. The lower mass objects ultimately end up as He white dwarfs, with almost all hydrogen consumed, first by core burning and convection and then when the core is exhausted, by a shell-burning phase.