Imaging surface spots from space-borne photometry

Abstract

A general introduction to the foundations of spot modelling is given. It considers geometric models of the surface brightness distribution in late-type stars as can be derived from their wide-band optical light curves. Spot modelling is becoming more and more important thanks to the high-precision, high duty cycle photometric time series made available by space-borne telescopes designed to search for planets through the method of transits. I review approaches based on a few spots as well as more sophisticated techniques that assume a continuous distributions of active regions and adopt regularization methods developed to solve ill-posed problems. The use of transit light curves to map spots occulted by a planet as it moves across the disc of its host star is also briefly described. In all the cases, the main emphasis is on the basic principles of the modelling techniques and on their testing rather than on the results obtained from their application.