Microlensing extended stellar sources

We have developed a code to compute multi-colour microlensing lightcurves for extended sources, including the effects of limb darkening and photospheric star spots as a function of spot temperature, position, size and lens trajectory. Our model also includes the effect of structure within the spot and rotation of the stellar source. Our results indicate that star spots generally give a clear signature only for transit events. Moreover, this signature is strongly suppressed by limb darkening for spots close to the limb – although such spots can be detected by favourable lens trajectories.