Precision modelling of M dwarf stars: the magnetic components of CM Draconis

The eclipsing binary CM Dra contains nearly identical red dwarfs of spectral class dM4. 5. Their masses and radii have been reported with unprecedentedly small statistical errors. When compared with standard stellar models of appropriate age (4 Gyr), the empirical results indicate that both components are larger in R, and lower in luminosity L, by several standard deviations. Here, we attempt at first to model the components in the context of standard stellar models using differ