A multiple spot model for simultaneous solution of light curves and distorted line profiles of spotted stars

This paper is devoted to the effects of dark starspots on observed light curves and line profiles. A new formulation of the starspot model with multiple spots and arbitrary spot shapes is derived which allows for a numerical solution of light and colour curves and distorted line profiles simultaneously. The effects of differential rotation and the existence of a penumbra have also been considered. A parameter study demonstrates the influences of different spot parameters on the theoretical light curves and rotation profiles. The computer code is applicable for single stars as well as for eclipsing close binaries allowing for ellipticity effect and reflection effect.