The Astrophysical Journal
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 M⊙ and 0.33 ± 0.02 R⊙. 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 M⊙, which would make the system at least 3 Gyr old.
Vaccaro, Todd R.; Rudkin, Mark J.; Kawka, Adéla; Vennes, Stéphane; Oswalt, T. D.; Silver, Isaac M.; Wood, Matt A.; and Smith, Jonathan Allyn, "LP 133-373: A New Chromospherically Active Eclipsing dMe Binary With A Distant, Cool White Dwarf Companion" (2007). Aerospace, Physics, and Space Science Faculty Publications. 358.