1995A&A...301..707J

Orbital elements are derived from CORAVEL measurements for the coolest known barium star HD 121447 (K7IIIBa5). The orbital period of P_orb=185.7d is the second shortest among barium stars. A photometric monitoring reveals small amplitude variations with a period P_orb/2. The phase of the variations and the stability of the color indices are compatible with the system being an ellipsoidal variable. If the red giant is located on the first giant branch, the analysis of the light curve and the orbital elements yield the following parameters for the system: 1.5=<M₁(M_☉)=<1.7, 0.5=<M₂(M_☉)=<0.7, 68deg≥i ≥48deg, 53=<R₁(R_☉)=<61, 173=<A(R_☉)=<184, and -2.2=<M_bol,1=←2.4 (where the indices 1 and 2 stand for the giant and the companion, respectively). The mass of the invisible companion is compatible with a white dwarf. Possible binary scenarios for this system are briefly discussed. In particular, the short orbital period of this barium star makes it hardly possible for the AGB progenitor of the current white dwarf to fit in the system without having filled its Roche lobe. Wind accretion in a detached system can thus not account for the chemical peculiarities exhibited by HD 121447. Another peculiarity of this system is the absence of synchronization between the giant rotation and the orbital motion, although the orbit has been circularized by dissipative processes.