1997A&A...324.1096D

An analysis of 278 spectra of the line-profile variable λ Scorpii leads to the following conclusions. λ Sco is the primary of a binary system. The radial-velocity variations have a peak-to-peak amplitude of ∼60km/s and an orbital period of 5.959 days. The orbit is not circular but has an eccentricity of 0.29. The 5.959^d-binary system probably moves in orbit with another distant, as yet unknown third star. By means of three five-hour time series of high-resolution spectra, the oscillations of the rapidly rotating β Cephei-type main component are investigated. Line-profile variations, which reveal travelling subfeatures across the lines, are discovered. λ Sco is so far one of the very few βCephei stars in which such a moving-bump phenomenon is detected. Radial-velocity variations are derived from the data and analysed to reveal a main oscillation frequency near 4.66cycles/day, and some more candidate frequencies. λ Sco is a non-radially pulsating β Cephei star which rotates supersynchronously. The characteristics of λ Sco and the ζ Oph stars are briefly addressed. Despite the common line-profile behaviour, spectral type, and vsin(i), we find no evidence of circumstellar material around λ Sco.