  We present a novel method for measuring the masses of evolved stars from
their limb-darkening observations parameterized as a linear-plus-square-root
function with two coefficients. The coefficients of the law are related to
integrated moments of the intensity and carry information about the extension
of the stellar atmosphere, which is correlated to the ratio of the stellar
radius to mass, R/M. Here, we show why the limb-darkening law is related to the
R/M, and apply this result to limb-darkening observations of the microlensing
event EROS-BLG-2000-5.
