2 Samples and observations

 

2.1 Barium-star samples

The two samples of barium stars with strong and mild anomalies (Ba4 or Ba5 and Ba < 1, Ba1 or Ba2, respectively, on the scale defined by Warner 1965) to which belong the binaries presented in this paper were taken from the list of Lü et al. (1983). The strong barium stars were followed to address the question of whether binarity is a necessary condition to form a strong barium star. The mild barium stars were selected to provide a comparison set. The samples are described in more details in Tables 1 and 2 of Paper I.

For the strong barium sample, 29 stars were followed yielding 29 spectroscopic orbits. Eight of them are described in Sect. 3, 18 in Paper I, 2 in Griffin et al. (1996) and 1 in Jorissen et al. (1995). For the mild barium set, 12 binaries are presented in Sect. 3 whereas 14 may be found in Paper I and 1 in Griffin (1991).

The individual measurements will be available at the Centre de Données Stellaires (CDS) in Strasbourg or on our dedicated web page:
obswww.unige.ch/$\sim$udry/cine/barium/barium.html.

2.2 Observations

Starting back in 1984, the observations were performed with the two CORAVEL spectrometers (Baranne et al. 1979), on the 1-m Swiss telescope at the Haute-Provence Observatory for the northern sky and on the 1.54-m Danish telescope at La Silla (Chile, ESO) for the southern sky. The distributions of individual errors ($\overline{\varepsilon_i}$=0.3 kms^-1), number of measurements ($\overline{N}$=19) and time span ($\overline{\Delta T}$=3398d) per star are displayed in Fig. 1 of Paper I. They attest the large observational effort dedicated to these programmes and the good quality and homogeneity of the measurements.

More detailed information on the scientific background of the different projects, on the sample selection strategies, or on the observational characteristics of the measurements can be found in Jorissen et al. (1998) and in Paper I as also in Gòmez et al. (1997) and Menessier et al. (1997).