Doppler imaging of stellar surfaces

The process of recovering the geometric information encoded in the time varying line pro les of rotating stars to obtain maps or images of the surface features on those stars has come to be known in stellar astronomy by the title \Doppler imaging", although other titles have been used. The principles of Doppler imaging are fairly well known, but the extent of application has been less than might have been expected given the ready availability now of the electronic detectors, the large telescopes and the computing power needed to undertake this sort of imaging.