Contribution a l'etude des spectres composites. VII. HD 16646. Contribution to the study of composite spectra. VII. HD 16646.

HD 16646 is listed by Hynek (1938) as a star suspected of having a composite spectrum. Classifications made by Abt and by us, and Stroemgren photometry by Olsen, indicate that the star is not a spectrum binary but a metal-deficient F dwarf. It is, however, a binary star; 67 radial velocities, obtained at various observatories, show HD 16646 to be a single-lined spectroscopic binary with the following orbital elements: P=328.91days; T=2447033.3JD; ω=1.8deg; e=0.114; K=11.93km/s; V_o_=-5.03km/s; a sin i=53.60Gm; f(m)=0.0568M_sun_. The secondary component, unseen in the spectrum, may be a dwarf K star; the linear separation of the components is no more than about 1.2AU, and their angular separation is not expected to exceed 0.015".