We have found a new low-mass , double-lined , detached eclipsing binary , GU Boo , among a sample of new variables from the ROTSE-I database .
The binary has an orbital period of 0.488728 \pm 0.000002 days , and estimated apparent magnitudes V _ { rotse } \simeq 13.7 and I \simeq 11.8 .
Our analysis of the light and radial velocity curves of the system yields individual masses and radii of M _ { 1 } = 0.610 \pm 0.007 M _ { \sun } , M _ { 2 } = 0.599 \pm 0.006 M _ { \sun } , R _ { 1 } = 0.623 \pm 0.016 R _ { \sun } , R _ { 2 } = 0.620 \pm 0.020 R _ { \sun } .
The stars in GU Boo are therefore very similar to the components of the eclipsing binary YY Gem .
For this study we have adopted a mean effective temperature for the binary of T _ { eff } = 3870 \pm 130 K. Based on its space velocities we suggest that GU Boo is a main sequence binary , possibly with an age of several Gyr .
The metallicity of the binary is not well constrained at this point but we speculate that it should not be very different from solar .
We have compared the physical parameters of GU Boo with current low-mass stellar models , where we accounted for uncertainties in age and metallicity by considering a wide range of values for those parameters .
Our comparisons reveal that all the models underestimate the radii of the components of GU Boo by at least 10–15 % .
This result is in agreement with the recent studies of YY Gem and CU Cnc .