A photometric and spectroscopic study of NSVS 14256825: the second sdOB+dM eclipsing binary

L. A. Almeida; F. Jablonski; J. Tello; C. V. Rodrigues

doi:10.1111/j.1365-2966.2012.20891.x

paper

A photometric and spectroscopic study of NSVS 14256825: the second sdOB+dM eclipsing binary

arXiv:1203.1266 · doi:10.1111/j.1365-2966.2012.20891.x

Abstract

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 ( $P_{orb} 0.1$ 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, $lo g g_{1} = 5.50 \pm 0.05$ , 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 ($i = 82\fdg5\pm0\fdg3$ and $q = M_{2} / M_{1} = 0.260 \pm 0.012$ , respectively), the components of the system have $M_{1} = 0.419 \pm 0.070 M_{⊙}$ , $R_{1} = 0.188 \pm 0.010 R_{⊙}$ , $M_{2} = 0.109 \pm 0.023 M_{⊙}$ , and $R_{2} = 0.162 \pm 0.008 R_{⊙}$ . From its spectral characteristics, the hot star is classified as an sdOB star.

8 pages, 7 figures, accepted for publication in MNRAS

A photometric and spectroscopic study of NSVS 14256825: the second sdOB+dM eclipsing binary

Abstract

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