We present the discovery of CoRoT 223992193 , a double-lined , detached eclipsing binary , comprising two pre-main sequence M dwarfs , discovered by the CoRoT space mission during a 23-day observation of the 3 Myr old NGC 2264 star-forming region .
Using multi-epoch optical and near-IR follow-up spectroscopy with FLAMES on the Very Large Telescope and ISIS on the William Herschel Telescope we obtain a full orbital solution and derive the fundamental parameters of both stars by modelling the light curve and radial velocity data .
The orbit is circular and has a period of 3.8745745 \pm 0.0000014 days .
The masses and radii of the two stars are 0.67 \pm 0.01 and 0.495 \pm 0.007 M _ { \sun } and 1.30 \pm 0.04 and 1.11 ~ { } ^ { +0.04 } _ { -0.05 } R _ { \sun } , respectively .
This system is a useful test of evolutionary models of young low-mass stars , as it lies in a region of parameter space where observational constraints are scarce ; comparison with these models indicates an apparent age of \sim 3.5–6 Myr .
The systemic velocity is within 1 \sigma of the cluster value which , along with the presence of lithium absorption , strongly indicates cluster membership .
The CoRoT light curve also contains large-amplitude , rapidly evolving out-of-eclipse variations , which are difficult to explain using starspots alone .
The system ’ s spectral energy distribution reveals a mid-infrared excess , which we model as thermal emission from a small amount of dust located in the inner cavity of a circumbinary disk .
In turn , this opens up the possibility that some of the out-of-eclipse variability could be due to occultations of the central stars by material located at the inner edge or in the central cavity of the circumbinary disk .