We present an analysis of UBVR _ { C } I _ { 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 _ { orb } \sim 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 } = 5.50 \pm 0.05 , and the helium abundance , n ( He ) / n ( H ) = 0.003 \pm 0.001 , 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 = 82 \aas@@fstack { \circ } 5 \pm 0 \aas@@fstack { \circ } 3 and q = M _ { 2 } / M _ { 1 } = 0.260 \pm 0.012 , 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 .