The early-type binary KX Velorum.

Abstract

A spectroscopic study of the double-lined OB-type binary system KX Vel is presented. Radial velocities were measured on 20 new CCD spectra and 4 high dispersion IUE SWP images. From a combination with early photographic data, the orbital period was found to be 26.306d. The high precision radial velocity curve of the evolved primary component allowed for an accurate determination of the highly eccentric orbit (e=0.59) using a SIMPLEX based fit procedure. The less luminous secondary main sequence component could be identified in spectra taken at phases shortly before and after the periastron passage, at which the high opposite radial velocities of both components made a deconvolution of the line blends possible. The combination of an earlier eclipse measurement with the new spectroscopic elements yields an ephemeris for expected future eclipse minima. Further spectroscopic observations (close to periastron phases) and photometric measurements (at eclipse epochs) are suggested to derive the absolute dimensions of the binary components of this detached close binary system.