1998A&AS..130..415G

We present an observing program undertaken at Observatoire de Haute-Provence, for the search and study of spectroscopic binaries among Am stars. HD 125273 was recognized as an Am star some time ago (Olsen, 1980A&AS...39..205O, Abt, 1984pJ...285..247A) observations, carried out with the CORAVEL spectrovelocimeter, show that this star is a double-lined spectroscopic binary; its orbital elements are as follows: P=7.482664days; T=2448665.660JD; ω₁=355.3°; e=0.071; K₁=49.82km/s; K₂=51.75km/s; V₀=-17.42km/s; a₁sini=5.113Gm; a₂sini=5.311Gm; M₁sin³i=0.412M_☉; M₂sin³i=0.396M_☉. Stroemgren photometry of the star (Olsen, 1983A&AS...54...55O) permits us to estimate the following mean physical parameters for the components of the binary: T_eff=7500K; logg=3.70; M_v=1.24; M=2.1M_☉; R=3.2R_☉, and to specify the evolutionary status of the system. Assuming the above mass for the components, we found i∼35° and a ∼26R_☉. This system is thus a detached one without possibility of eclipses. It is likely that the two components are Am stars of very close characteristics. The vsini values, determined from the correlation dips given by CORAVEL, are near 11km/s for both components. We retain for this binary the hypothesis of rotation-revolution synchronism, because it leads to a value of the radius of the stars in agreement both with the above value and the results of a previous study by Kitamura & Kondo (1978Ap&SS..56..341K) of similar, but eclipsing, systems. The ratio of the correlation dip areas indicates a magnitude difference {DELTA}m_v∼0.2mag. As expected in detached systems of main sequence stars, such as Am's, HD 125273 obeys the mass-luminosity law.