SIMBAD references

We apply stellar surface imaging techniques for studying non-radial pulsations. Stellar surface imaging is based on inversions of time series of variable spectral line profiles without making assumptions on the specific shape of the pulsations. The inversion results in an image of the stellar surface in which the sectoral and tesseral modes can in many cases be distinguished, and the pulsational degree l and the azimuthal order |m| can be determined.