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تسجيل مستخدم جديدA photometric and spectroscopic study of NSVS 14256825: the second sdOB+dM eclipsing binary
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We present an analysis of UBVR$_{rm C}$I$_{rm C}$JH photometry and phase-resolved optical spectroscopy of NSVS 14256825, an HW Vir type binary. The members of this class consist of a hot subdwarf and a main-sequence low-mass star in a close orbit ($P_{rm orb} ~ 0.1$ d). Using the primary-eclipse timings, we refine the ephemeris for the system, which has an orbital period of 0.11037 d. From the spectroscopic data analysis, we derive the effective temperature, $T_1 = 40000 pm 500$ K, the surface gravity, $log g_1 = 5.50pm0.05$, and the helium abundance, $n(rm He)/n(rm H)=0.003pm0.001$, for the hot component. Simultaneously modelling the photometric and spectroscopic data using the Wilson-Devinney code, we obtain the geometrical and physical parameters of NSVS 14256825. Using the fitted orbital inclination and mass ratio ($i = 82fdg5pm0fdg3$ and $q = M_2/M_1 = 0.260pm0.012$, respectively), the components of the system have $M_1 = 0.419 pm 0.070 M_{odot}$, $R_1 = 0.188 pm 0.010 R_{odot}$, $M_2 = 0.109 pm 0.023 M_{odot}$, and $R_2 = 0.162 pm 0.008 R_{odot}$. From its spectral characteristics, the hot star is classified as an sdOB star.
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