We report the discovery of the partially eclipsing binary LP 133-373. Nearly identical eclipses along with observed photometric colors and spectroscopy indicate that it is a pair of chromospherically active dM4 stars in a circular 1.6 day orbit. Light and velocity curve modeling to our differential photometry and velocity data show that each star has a mass and radius of 0.340+/-0.014 Msolar and 0.33+/-0.02 Rsolar. The binary is itself part of a common proper motion pair with LP 133-374, a cool DC or possible DA white dwarf with a mass of 0.49-0.82 Msolar, which would make the system at least 3 Gyr old
Vaccaro, Todd R.; Kawka, A.; Oswalt, T. D.; Silver, I.; Wood, M.; and Smith, J. Allyn, "LP 133-373: A New Chromospherically Active Eclipsing dMe Binary with a Distant, Cool White Dwarf Companion" (2007). Physics and Astronomy Faculty Publications. 4.