The magnetic field of the double-lined spectroscopic binary system HD 5550

摘要: (Abridged) In the framework of BinaMicS project, we have begun a study magnetic properties sample intermediate-mass and massive short-period binary systems, as function binarity properties. We report in this paper characterisation field HD 5550, double-lined spectroscopic system intermediate-mass, using high-resolution spectropolarimetric Narval observations 5550. first fit intensity spectra Zeeman/ATLAS9 LTE synthetic to estimate effective temperatures, microturbulent velocities, abundances some elements both components, well light-ratio system. then least-square deconvolved $I$ profiles determine radial projected rotational velocities stars. analysed shape evolution LSD $V$ oblique rotator model characterise fields We confirm Ap nature primary, previously reported literature, find that secondary displays spectral characteristics typical an Am star. While is clearly detected lines no secondary, any our observation. If dipolar were present at surface star, its polar strength must be below 40 G. The faint variability observed Stokes star allowed us propose rotation period $6.84_{-0.39}^{+0.61}$ d, close orbital ($\sim$6.82 d), suggesting synchronised with orbit. By fitting profiles, component hosts inclined axis angle $\beta=156\pm17$ $^{\circ}$ $B_{\rm d}=65 \pm 20$ weakest known for