Fundamental parameters for double-lined spectroscopic and detached eclipsing binary system J064726.39+223431.6

We present a study of the detached eclipsing binary J064726.39 + 223431.6 using spectra from the LAMOST medium resolution spectra and Transiting Exoplanet Survey Satellite photometry. We use full-spectrum fitting to derive radial velocities and spectral parameters: T-effA,T-B = 6177 , 5820 K, V sin i(A,B) = 59,50 km s (-1), and [Fe/H](A,B) = -0.19 dex. The orbital solution and light-curve analysis suggest that it is a close pair of fast rotating stars on a circular orbit. We measure their masses to be M-A,M-B = 1.307 +/- 0.007, 1.129 +/- 0.005 Me and their radii to be R-A,R-B = 1.405 +/- 0.052, 1.219 +/- 0.060 R-?, resulting in surface gravities of log (g)(A,B) = 4.259 +/- 0.033, 4.319 +/- 0.042 (cgs). Theoretical models cannot match all of these properties, predicting significantly higher T-eff for a given metallicity. The derived age of the system is 1.56 Gyr, which indicates that both components are younger than Sun, which contradicts to much longer orbit's circularization time-scale.