1999A&A...341L..63D

We have discovered a third detached M dwarf eclipsing binary system, for which we present an accurate radial velocity orbit and a preliminary light curve. From those data, we derive individual masses (0.433 and 0.397M_☉) with 0.4% accuracy, the most accurate to date for M dwarfs. Both stars are clearly sub-luminous for their mass, compared with solar metallicity stellar models or empirical mass-luminosity relations. Their spectral types are also later than expected. This indicates a metal-rich composition ([M/H]∼0.5). An infrared light curve and a more accurate trigonometric parallax would make this system a stringent test of our understanding of M dwarfs.