SIMBAD references

We report the results of abundance determinations for the components of the SB2 star HD 153720 from high resolution (R=60000) echelle high signal-to-noise spectra of the wavelength region 3595-10260Å taken with the 2.7m telescope of the McDonald Observatory We found the values of the atmospheric parameters of the primary to be effective temperature T_eff=7425K and surface gravity logg=4.0cgs, and of the secondary to be T_eff=7125K and logg=3.9cgs. The microturbulent velocity is v_micro=2.7km/s for both components, and the projected rotational velocity is vsini=15km/s also for both components. The abundances of about 20 elements were determined with the method of spectrum synthesis. The components of HD 153720 are metallic-line stars. Possible inconsistencies between old and new measurements of radial velocities may be explained by the existence of third body in this system. A review of recent high resolution spectral observations of eight A4-F1 binaries shows that only one of these systems can be classified as normal.