Doppler images of rotating stars using maximum entropy image reconstruction

The paper presents an improved version of the Doppler imaging technique, which now uses the principles of maximum entropy image reconstruction to derive spatially resolved images of rapidly rotating stars. It examines the effects that noise, finite spectral resolution, and uncertain stellar parameters are likely to have on real data sets, and demonstrates through a variety of test cases that the technique is efficient and accurate at recovering test images from realistic synthetic spectral data. At the high signal-to-noise ratio and resolution typical of real stellar spectra, the images are well constrained by the data set alone, rather than by entropy criteria. The technique is currently being used to study cool starspots on RS CVn and FK Com stars, and the surface abundance distributions on Ap stars.