  The formation and evolution of stars depends on various physical aspects of
stellar matter, including the equation of state (EOS) and transport properties.
Although often dismissed as `ideal gas-like' and therefore simple, states
occurring in stellar matter are dense plasmas, and the EOS has not been
established precisely. EOS constructed using multi-physics approaches found
necessary for laboratory studies of warm dense matter give significant
variations in stellar regimes, and vary from the EOS commonly used in
simulations of the formation and evolution of stars. We have investigated the
sensitivity of such simulations to variations in the EOS, for sun-like and
low-mass stars, and found a strong sensitivity of the lifetime of the Sun and
of the lower luminosity limit for red dwarfs. We also found a significant
sensitivity in the lower mass limit for red dwarfs. Simulations of this type
are also used for other purposes in astrophysics, including the interpretation
of absolute magnitude as mass, the conversion of inferred mass distribution to
the initial mass function using predicted lifetimes, simulations of star
formation from nebulae, simulations of galactic evolution, and the baryon
census used to bound the exotic contribution to dark matter. Although many of
the sensitivities of stellar physics to the EOS are large, some of the inferred
astrophysical quantities are also constrained by independent measurements,
although the constraints may be indirect and non-trivial. However, it may be
possible to use such measurements to constrain the EOS more than presently
possible by established plasma theory.
