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Description
Low-mass stars in eclipsing binary systems show radii larger and effective temperatures lower than theoretical stellar models predict for isolated stars with the same masses. Eclipsing binaries with low-mass components are hard to find due to their low luminosity. As a consequence, the analysis of the known low-mass eclipsing systems is key to understand this behavior. We aim to investigate the mass-radius relation for low-mass stars and the cause of the deviation of the observed radii in low-mass detached eclipsing binary stars (LMDEB) from theoretical stellar models. We developed a physical model of the LMDEB system NSVS 10653195 to accurately measure the masses and radii of the components. We obtained several high-resolution spectra in order to fit a spectroscopic orbit. Standardized absolute photometry was obtained to measure reliable color indices and to measure the mean Teff of the system in out-of-eclipse phases. We observed and analyzed optical VRI and infrared JK band differential light-curves which were fitted using PHOEBE. A Markov-Chain Monte Carlo (MCMC) simulation near the solution found provides robust uncertainties for the fitted parameters. NSVS 10653195 is a detached eclipsing binary composed of two similar stars with masses of M1=0.6402+/-0.0052M_{sun}_ and M2=0.6511+/-0.0052M_{sun}_ and radii of R1=0.687^+0.017^_-0.024_R_{sun}_ and R2=0.672^+0.018^_-0.022_R_{sun}_. Spectral types were estimated to be K6V and K7V. These stars rotate in a circular orbit with an orbital inclination of i=86.22+/-0.61 degrees and a period of P=0.5607222(2)d. The distance to the system is estimated to be d=135.2^+7.6^_-7.9_pc, in excellent agreement with the value from Gaia. If solar metallicity were assumed, the age of the system would be older than log(age)~8 based on the M_bol_-logTeff diagram. NSVS 10653195 is composed of two oversized and active K stars. While their radii is above model predictions their Teff are in better agreement with models.
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