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HS 0705+6700: a new eclipsing sdB binary

H. Drechsel·U. Heber·R. Napiwotzki·R. Ostensen·J. -E. Solheim·F. Johannessen·S. L. Schuh·J. Deetjen·S. Zola
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Abstract

We report the discovery of an eclipsing binary - HS 0705+6700 - being an sdB star with a faint companion. From its light curve the orbital period of 8263.87 s, the mass ratio of the system q = 0.28, the inclination of 84.4 deg and other system parameters are derived. The companion does not contribute to the optical light of the system except through a strong reflection effect. The semi-amplitude of the radial velocity curve K1 = 85.8 km/s and a mass function of f(m) = 0.00626 Msun are determined. A spectroscopic analysis of the blue spectra results in Teff = 28800K, log g = 5.40, and log n(He)/n(H) = -2.68. These characteristics are typical for sdB stars, as is its mass of 0.48 Msun. According to its mass (0.13 Msun) and radius (0.19 Rsun), the companion is an M dwarf. The primary is in a core helium burning phase of evolution, and the system must have gone through a common envelope stage when the primary was near the tip of the red giant branch.

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H. Drechsel, U. Heber, R. Napiwotzki, R. Ostensen, J. -E. Solheim, F. Johannessen, S. L. Schuh, J. Deetjen, S. Zola. 2001-10-09. HS 0705+6700: a new eclipsing sdB binary. https://doi.org/10.1051/0004-6361%3A20011376

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