3 Radial-velocity curves and orbital parameters

  The same presentation strategy as in Paper I is adopted. The orbital elements and the phase-folded radial-velocity curves are provided for the binaries with stable orbital solutions. Badly constrained parameters are readily identifiable by their large uncertainties. In case the period has to be fixed to obtain a satisfactory orbit, it is fixed to a minimized value determined by the minimum residue around the obtained solution. In such a case, no uncertainty is given for the fixed period. When the star is clearly binary but the period is not sufficiently covered to derive a preliminary orbit, only a minimum period is given. The radial velocities in function of Julian dates are then displayed.

Figure 1 and Table 1 provide the results for the strong barium sample (8 orbits) whereas Fig. 2 and Table 2 give the information for the mild barium binaries (10 orbits + 2 minimum-period binaries).

  

Figure 1: Phase-folded radial-velocity curves for the strong barium stars. Open circles are for DAO measurements

  

Figure 2: Phase-folded radial-velocity curves for the mild barium stars. Open circles are for DAO measurements. Due to the non-complete coverage of the orbit a minimized period has been fixed for HD 53199. Long-period stars without orbital solution have their radial velocities displayed as a function of Julian dates

 

Figure 2: continued

  

Table 1: Orbital elements for the strong barium stars. N is the number of measurements used to derive the orbital solution and O-C the residue around this solution. $\Delta T$ is the span of the observations

For the uncompletely-covered star HD 53199, the period has been fixed to a minimized value. In a few cases (see Jorissen et al. 1998), even though the Lucy-Sweeney test was compatible with a circular orbital solution (Lucy & Sweeney 1971), the free-eccentricity solution has been given because their is no physical argument to prefer circular orbits in the case of barium stars. Two stars ( HD 46407 and HD 223617) have an orbital solution derived from a combined set of CORAVEL measurements and radial velocities obtained at the Dominion Astrophysical Observatory (DAO) by McClure & Woodsworth (1990). The fair number of new CORAVEL measurements allows us to slightly improve the previously published orbits.

Finally, the star HD 101079 deserves a comment. Only 7 CORAVEL radial-velocity measurements are available to date. They permit to derive two equally-probable orbital solutions with periods of 1588d and 3120d. In the coming months, new measurements will allow us to decide between the two solutions but for the moment only a minimum period P>1550 d is given in Table 2.

  

Table 2: Orbital elements for the mild barium stars. No uncertainties are given for fixed parameters

Acknowledgements

This research has been supported partly by the Fonds National de la Recherche Scientifique (Switzerland, Belgium) and the University of Geneva (Geneva Observatory).