Surface imaging of stellar non-radial pulsations II. The (beta) Cephei star (omega) Sco

We apply the surface imaging technique to high-resolution spectra of the rapidly rotating (beta) Cep-type star (omega)^1 Sco which shows strong line-profile variations in the Si III (lambda)4552, 4567, 4574 (angstrom) triplet. These variations have been interpreted in terms of non-radial pulsations by Telting & Schrijvers (1998). Their analysis of the spectral time series with traditional Fourier transforms resulted in one significant frequency, suggesting that the profile variations are due to only one dominant pulsation mode. Here we apply a spectral inversion technique to the same time series of the profiles. Assuming only temperature fluctuations due to pulsations, we obtain an image of the dominant pulsation mode. We estimate the pulsation degree from the image, put constraints on the azimuthal number of the mode, and study the latitudinal distribution of the pulsation pattern. In addition to the known dominant mode we find traces of a second pulsation mode.