2 Spectroscopic data

For the stars V337 Aql, V649 Cas, and V382 Cyg, spectra were obtained at the Calar Alto Observatory (Spain) with the coudé spectrograph of the 2.2 m telescope, yielding a reciprocal dispersion of 8.5 Å mm^-1 and a resolving power of 24 000 to 32 000 (for further details see Lorenz et al. 1998). In most cases, spectra were taken around quadrature phases, since the orbits could be assumed as circular.

For the star V431 Pup we obtained spectra at the ESO La Silla Observatory (Chile). The ESO 1.52 m telescope with ECHELEC was used in the years 1992 and 1993, with a reciprocal dispersion of 3.8 Å mm^-1, and a resolving power of 23 000 to 32 000. In 1994, the CAT/CES equipment was used, with a reciprocal dispersion of 2.6 Å mm^-1 and a resolving power of about 56 000 (for further details see Mayer et al. 1997).

For a journal of the spectra of our four program stars together with measured radial velocities see Table 1. Radial velocities of the binary components were derived by fitting multiple Gaussian profiles to blended features. In cases where the lines of both components were clearly separated, also the SPEFO code was used (this code compares the line profile with its reflection, see Horn et al. 1996 and Skoda 1996).