2003MNRAS.342...61G

Radial velocity observations of HD 100054B and 187258 with CORAVEL instruments at Haute-Provence and Cambridge Observatories are reported. Known as Am/Fm metallic-line stars, both objects were included in our spectroscopic survey of Am-type stars, the purpose of which was to determine the frequency and properties of binaries in this stellar family.

HD 100054B is found to be a single-lined spectroscopic binary with a variable value of V₀, the systemic velocity of the centre of gravity of the pair. The variation of this parameter is interpreted in terms of orbital motion of an unseen third body with a much longer period. The orbital elements are derived for both the short- and the long-period orbits. We find P = 12.79430 d, T = 2449781.19 HJD, ω= 137°, e = 0.028, K₁= 18.69 km.s^–1, a₁sin i = 3.29 Gm and f (m) = 0.0087 M_☉for the short-period orbit; and P = 874.2 d, T = 244 9377 HJD, ω= 172°, e = 0.097, K₁= 5.30 km.s^–1, V₀ =-13.52 km.s^–1, a₁sin i = 63.4 Gm and f (m) = 0.013 M_☉for the long-period orbit.

HD 187258 is found to be a single-lined spectroscopic binary, the orbital elements of which are P = 25.8048 d, T = 244 9628.91 HJD, {formmu6}, e = 0.370, K₁= 17.36 km.s^–1, V₀=-34.76 km.s^–1, a₁sin i = 5.72 Gm and f (m) = 0.011 M_☉.

Physical parameters of the primary components of these systems are derived.